{"id":10008008,"date":"2023-06-28T11:00:52","date_gmt":"2023-06-28T03:00:52","guid":{"rendered":"https:\/\/ityet.com\/?p=10008008"},"modified":"2023-06-28T11:00:52","modified_gmt":"2023-06-28T03:00:52","slug":"g1%e5%9e%83%e5%9c%be%e5%9b%9e%e6%94%b6%e5%8f%82%e6%95%b0%e8%b0%83%e4%bc%98%e5%8f%8amysql%e8%99%9a%e5%bc%95%e7%94%a8%e9%80%a0%e6%88%90gc%e6%97%b6%e9%97%b4%e8%bf%87%e9%95%bf%e5%88%86%e6%9e%90","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10008008","title":{"rendered":"G1\u5783\u573e\u56de\u6536\u53c2\u6570\u8c03\u4f18\u53caMySQL\u865a\u5f15\u7528\u9020\u6210GC\u65f6\u95f4\u8fc7\u957f\u5206\u6790 | \u4eac\u4e1c\u4e91\u6280\u672f\u56e2\u961f"},"content":{"rendered":"<h2>1. \u80cc\u666f<\/h2>\n<p>\u6211\u65b9\u6709\u4e00\u5e94\u7528\uff0c\u5076\u5c14\u4f1a\u51fa\u73b0GC\u65f6\u95f4\u8fc7\u957f\uff08\u95f4\u9694\u7ea64\u5c0f\u65f6\uff09\uff0c\u5bfc\u81f4\u6027\u80fd\u6ce2\u52a8\u7684\u95ee\u9898(\u63a5\u53e3\u6700\u957f\u9700\u8981\u8017\u65f63\u79d2\u4ee5\u4e0a)\u3002\u7ecf\u6392\u67e5\u4e3aG1\u5783\u573e\u56de\u6536\u5668\u53c2\u6570\u914d\u7f6e\u4e0d\u5f53 \u53e0\u52a0 MySQL \u94fe\u63a5\u8d85\u8fc7\u95f2\u7f6e\u65f6\u95f4\u56de\u6536\uff0c\u4ea7\u751f\u5927\u91cf\u7684\u865a\u5f15\u7528\uff0c\u5bfc\u81f4G1\u5728\u6267\u884c\u8001\u5e74\u4ee3\u6df7\u5408GC\uff0c\u6807\u8bb0\u9636\u6bb5\u8017\u65f6\u8fc7\u957f\u5bfc\u81f4\u3002\u4ee5\u4e0b\u4e3a\u5bf9\u6b64\u95ee\u9898\u7684\u5206\u6790\u53ca\u95ee\u9898\u603b\u7ed3\u3002<\/p>\n<p>\u6b64\u5916\uff0c\u6b64\u5e94\u7528\u56e0\u4e3a\u4f7f\u7528redis\u7f13\u5b58\u4e3a\u6570\u636e\u5e93\u7f13\u5b58\u4e00\u6bb5\u65f6\u95f4\u7684\u70ed\u70b9\u6570\u636e\uff0c\u5bfc\u81f4\u4e1a\u52a1\u8d77\u91cf\u521b\u5efa\u6570\u636e\u5e93\u94fe\u63a5\u540e\uff0c\u4f1a\u5f88\u5bb9\u6613\u88ab\u95f2\u7f6e\uff0c\u5bb9\u6613\u88ab\u6570\u636e\u5e93\u8fde\u63a5\u6c60\u5224\u5b9a\u4e3a\u95f2\u7f6e\u8fc7\u957f\u800c\u6e05\u7406\u3002<\/p>\n<h3>\u5e94\u7528\u80cc\u666f<\/h3>\n<p>JDK1.8 , mysql-connector-java-5.1.30, commons-dbcp-1.4, spring-4.3.20.RELEASE<\/p>\n<p>\u786c\u4ef6\uff1a8\u683816GB;<\/p>\n<h4>JVM\u542f\u52a8\u53c2\u6570\u6982\u8981\uff1a<\/h4>\n<pre><code>\n-Xms9984m -Xmx9984m -XX:MaxMetaspaceSize=512m -XX:MetaspaceSize=512m -XX:MaxDirectMemorySize=512m -XX:ParallelGCThreads=8 -XX:CICompilerCount=4 -XX:ConcGCThreads=4 -server -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1HeapRegionSize=32M -XX:SurvivorRatio=10 -XX:MaxTenuringThreshold=5 -XX:InitiatingHeapOccupancyPercent=45 -XX:G1ReservePercent=20 -XX:G1MixedGCLiveThresholdPercent=80 -XX:MaxGCPauseMillis=100 -XX:+ExplicitGCInvokesConcurrent -XX:+PrintGCDetails -XX:+PrintReferenceGC -XX:+PrintGCDateStamps -XX:+PrintHeapAtGC -Xloggc:\/export\/Logs\/app\/tomcat7-gc.log<\/code><\/pre>\n<h4>dbcp\u914d\u7f6e\uff1a<\/h4>\n<pre><code>\nmaxActive=20\ninitialSize=10\nmaxIdle=10\nminIdle=5\nminEvictableIdleTimeMillis=180000\ntimeBetweenEvictionRunsMillis=20000\nvalidationQuery=select 1<\/code><\/pre>\n<p>\u914d\u7f6e\u8bf4\u660e\uff1a<\/p>\n<blockquote>\n<ul>\n<li><code>maxActive=20<\/code>: \u8fde\u63a5\u6c60\u4e2d\u6700\u591a\u80fd\u591f\u540c\u65f6\u5b58\u5728\u7684\u8fde\u63a5\u6570\uff0c\u914d\u7f6e\u4e3a20\u3002<\/li>\n<li>`initialSize=10: \u6570\u636e\u6e90\u521d\u59cb\u5316\u65f6\u521b\u5efa\u7684\u8fde\u63a5\u6570\uff0c\u914d\u7f6e\u4e3a10\u3002<\/li>\n<li><code>maxIdle=10<\/code>: \u8fde\u63a5\u6c60\u4e2d\u6700\u5927\u7a7a\u95f2\u8fde\u63a5\u6570\uff0c\u4e5f\u5c31\u662f\u8bf4\u5f53\u8fde\u63a5\u6c60\u4e2d\u7684\u8fde\u63a5\u6570\u8d85\u8fc710\u4e2a\u65f6\uff0c\u591a\u4f59\u7684\u8fde\u63a5\u5c06\u4f1a\u88ab\u91ca\u653e\uff0c\u914d\u7f6e\u4e3a10\u3002<\/li>\n<li><code>minIdle=5<\/code>: \u8fde\u63a5\u6c60\u4e2d\u6700\u5c0f\u7a7a\u95f2\u8fde\u63a5\u6570\uff0c\u4e5f\u5c31\u662f\u8bf4\u5f53\u8fde\u63a5\u6c60\u4e2d\u7684\u8fde\u63a5\u6570\u5c11\u4e8e5\u4e2a\u65f6\uff0c\u4f1a\u81ea\u52a8\u6dfb\u52a0\u65b0\u7684\u8fde\u63a5\u5230\u8fde\u63a5\u6c60\u4e2d\uff0c\u914d\u7f6e\u4e3a5\u3002<\/li>\n<li>`minEvictableIdleTimeMillis=180000: \u8fde\u63a5\u5728\u8fde\u63a5\u6c60\u4e2d\u6700\u5c0f\u7a7a\u95f2\u65f6\u95f4\uff0c\u8fd9\u91cc\u914d\u7f6e\u4e3a3\u5206\u949f\uff0c\u8868\u793a\u8fde\u63a5\u6c60\u4e2d\u7684\u8fde\u63a5\u5728\u7a7a\u95f23\u5206\u949f\u4e4b\u540e\u5c06\u4f1a\u88ab\u79fb\u9664\uff0c\u907f\u514d\u957f\u65f6\u95f4\u5360\u7528\u8d44\u6e90\u3002<\/li>\n<li><code>timeBetweenEvictionRunsMillis=20000<\/code>: \u8fde\u63a5\u6c60\u4e2d\u7ef4\u62a4\u7ebf\u7a0b\u7684\u8fd0\u884c\u65f6\u95f4\u95f4\u9694\uff0c\u5355\u4f4d\u6beb\u79d2\u3002\u8fd9\u91cc\u914d\u7f6e\u4e3a20\u79d2\uff0c\u8868\u793a\u8fde\u63a5\u6c60\u4e2d\u4f1a\u6bcf\u969420\u79d2\u68c0\u67e5\u8fde\u63a5\u6c60\u4e2d\u7684\u8fde\u63a5\u662f\u5426\u7a7a\u95f2\u8fc7\u957f\u65f6\u95f4\u5e76\u4e14\u9700\u8981\u5173\u95ed\u3002<\/li>\n<li><code>validationQuery=select 1<\/code>: \u9a8c\u8bc1\u8fde\u63a5\u662f\u5426\u6709\u6548\u7684SQL\u8bed\u53e5\uff0c\u8fd9\u91cc\u4f7f\u7528\u4e86\u4e00\u4e2a\u7b80\u5355\u7684<code>SELECT 1<\/code>\u67e5\u8be2\u3002<\/li>\n<\/ul>\n<\/blockquote>\n<h3>\u5173\u952e\u8bcd<\/h3>\n<p>java G1GC \uff0c G1\u53c2\u6570\u8c03\u4f18\uff0cG1 STW \u8017\u65f6\u8fc7\u957f\uff0ccom.mysql.jdbc.NonRegisteringDriver\uff0cConnectionPhantomReference\uff0cPhantomReference\uff0c GC ref-proc spent too much time \uff0cGC remark\uff0cFinalize Marking<\/p>\n<h2>2. \u95ee\u9898\u6392\u67e5<\/h2>\n<h3>\u53ef\u7528\u7387\u62a5\u8b66<\/h3>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043943982\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<h3>\u65e5\u5fd7\u67e5\u8be2<\/h3>\n<p>\u67e5\u8be2\u672c\u5730\u65e5\u5fd7\uff0c\u627e\u5230\u4e0b\u6e38timeout\u7684\u63a5\u53e3\u65e5\u5fd7, \u5e76\u627e\u5230\u76f8\u5173IP\u4e3a\uff1a11.#.#.201<\/p>\n<h3>\u67e5\u770bjvm\u76d1\u63a7<\/h3>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043943983\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043943984\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u8fd9\u91cc\u6709\u4e2a\u95ee\u9898\uff0c\u56e0\u4e3a\u7cfb\u7edf\u5de5\u5177ump\u5bf9jvm \u7684\u76d1\u63a7\uff0c\u53ea\u5173\u6ce8young gc &#038; full gc, \u9057\u6f0f\u4e86G1\u7684\u6df7\u5408GC\uff0c \u5bfc\u81f4\u76f4\u63a5\u901a\u8fc7\u7cfb\u7edf\u76d1\u63a7\u672a\u53ca\u65f6\u53d1\u73b0GC\u8fc7\u957f\u7684\u95ee\u9898\u3002\u5230\u540e\u9762\u4e0b\u8f7d\u4e86gc\u65e5\u5fd7\uff0c\u6700\u7ec8\u5206\u6790\u5f97\u5230\u4e86 GC\u65f6\u95f4\u8d85\u8fc73.7\u79d2\u7684\u76d1\u63a7\u7ed3\u679c\uff0c\u8fd9\u4e5f\u662f\u95ee\u9898\u7684\u6839\u6e90\u3002<\/p>\n<h2>3. \u95ee\u9898\u5206\u6790<\/h2>\n<h3>GC\u65e5\u5fd7\u5206\u6790<\/h3>\n<pre><code>2023-06-03T14:40:31.391+0800: 184748.113: [GC pause (G1 Evacuation Pause) (young) (initial-mark), 0.1017154 secs]\n   [Parallel Time: 70.3 ms, GC Workers: 6]\n      [GC Worker Start (ms): Min: 184748113.5, Avg: 184748113.6, Max: 184748113.6, Diff: 0.1]\n      [Ext Root Scanning (ms): Min: 1.9, Avg: 2.1, Max: 2.2, Diff: 0.3, Sum: 12.3]\n      [Update RS (ms): Min: 9.7, Avg: 9.9, Max: 10.4, Diff: 0.7, Sum: 59.6]\n         [Processed Buffers: Min: 12, Avg: 39.5, Max: 84, Diff: 72, Sum: 237]\n      [Scan RS (ms): Min: 0.1, Avg: 0.7, Max: 1.2, Diff: 1.1, Sum: 4.0]\n      [Code Root Scanning (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]\n      [Object Copy (ms): Min: 56.9, Avg: 57.5, Max: 57.7, Diff: 0.8, Sum: 344.8]\n      [Termination (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]\n         [Termination Attempts: Min: 1, Avg: 1.0, Max: 1, Diff: 0, Sum: 6]\n      [GC Worker Other (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.1]\n      [GC Worker Total (ms): Min: 70.1, Avg: 70.1, Max: 70.2, Diff: 0.1, Sum: 420.9]\n      [GC Worker End (ms): Min: 184748183.7, Avg: 184748183.7, Max: 184748183.7, Diff: 0.0]\n   [Code Root Fixup: 0.0 ms]\n   [Code Root Purge: 0.0 ms]\n   [Clear CT: 0.4 ms]\n   [Other: 31.0 ms]\n      [Choose CSet: 0.0 ms]\n      [Ref Proc: 30.1 ms]\n      [Ref Enq: 0.1 ms]\n      [Redirty Cards: 0.2 ms]\n      [Humongous Register: 0.0 ms]\n      [Humongous Reclaim: 0.0 ms]\n      [Free CSet: 0.1 ms]\n   [Eden: 1760.0M(1760.0M)-&gt;0.0B(2080.0M) Survivors: 192.0M-&gt;224.0M Heap: 6521.7M(9984.0M)-&gt;4912.0M(9984.0M)]\nHeap after GC invocations=408 (full 0):\n garbage-first heap   total 10223616K, used 5029872K [0x0000000570000000, 0x00000005720009c0, 0x00000007e0000000)\n  region size 32768K, 7 young (229376K), 7 survivors (229376K)\n Metaspace       used 112870K, capacity 115300K, committed 115968K, reserved 1150976K\n  class space    used 12713K, capacity 13380K, committed 13568K, reserved 1048576K\n}\n [Times: user=0.45 sys=0.01, real=0.10 secs] \n2023-06-03T14:40:31.493+0800: 184748.215: [GC concurrent-root-region-scan-start]\n2023-06-03T14:40:31.528+0800: 184748.251: [GC concurrent-root-region-scan-end, 0.0359052 secs]\n2023-06-03T14:40:31.528+0800: 184748.251: [GC concurrent-mark-start]\n2023-06-03T14:40:31.623+0800: 184748.345: [GC concurrent-mark-end, 0.0942951 secs]\n2023-06-03T14:40:31.624+0800: 184748.347: [GC remark 2023-06-03T14:40:31.624+0800: 184748.347: [Finalize Marking, 0.0003013 secs] 2023-06-03T14:40:31.625+0800: 184748.347: [GC ref-proc, 3.7471488 secs] 2023-06-03T14:40:35.372+0800: 184752.094: [Unloading, 0.0254883 secs], 3.7778434 secs]\n [Times: user=3.88 sys=0.05, real=3.77 secs] \n2023-06-03T14:40:35.404+0800: 184752.127: [GC cleanup 4943M-&gt;4879M(9984M), 0.0025357 secs]\n [Times: user=0.01 sys=0.00, real=0.00 secs] \n2023-06-03T14:40:35.407+0800: 184752.129: [GC concurrent-cleanup-start]\n2023-06-03T14:40:35.407+0800: 184752.130: [GC concurrent-cleanup-end, 0.0000777 secs]\n{Heap before GC invocations=409 (full 0):\n garbage-first heap   total 10223616K, used 6930416K [0x0000000570000000, 0x00000005720009c0, 0x00000007e0000000)\n  region size 32768K, 67 young (2195456K), 7 survivors (229376K)\n Metaspace       used 112870K, capacity 115300K, committed 115968K, reserved 1150976K\n  class space    used 12713K, capacity 13380K, committed 13568K, reserved 1048576K<\/code><\/pre>\n<p>\u6839\u636e\u65e5\u5fd7\u5206\u6790\uff0c\u8be5G1\u5783\u573e\u56de\u6536\u5668\u5171\u8fdb\u884c\u4e86\u4e00\u6b21youngGC \u548c \u4e00\u6b21\u5e76\u53d1\u6807\u8bb0\u3002<\/p>\n<p>young GC\u572814:40:31.391\u5f00\u59cb\uff0c\u6682\u505c\u65f6\u95f4\u4e3a0.1017154\u79d2\uff0c\u662f young collection \u548c initial-mark \u9636\u6bb5\u3002\u5e76\u4e146\u4e2a GC \u5de5\u4f5c\u7ebf\u7a0b\u5e76\u884c\u6267\u884c\u4e8670.3\u6beb\u79d2\u3002GC \u8fc7\u7a0b\u4e2d\uff0c\u6709\u591a\u4e2a\u9636\u6bb5\u7684\u65f6\u95f4\u8bb0\u5f55\u548c\u8be6\u7ec6\u4fe1\u606f\u3002\u5806\u5927\u5c0f\u4ece6521M\u51cf\u5c11\u52304912M\u3002<\/p>\n<p>\u5e76\u53d1\u6807\u8bb0\u572814:40:31.493\u5f00\u59cb\uff0c\u5e76\u6d89\u53ca\u5e76\u53d1\u626b\u63cf\u3001\u6807\u8bb0\u548c\u91cd\u6807\u8bb0\u7b49\u9636\u6bb5\u3002\u5728\u6e05\u7406\u9636\u6bb5\u7ed3\u675f\u540e\uff0c\u5806\u5927\u5c0f\u4ece4943M\u51cf\u5c11\u52304879M\u3002<\/p>\n<p>\u56e0\u6b64\uff0c\u8be5 G1 \u5783\u573e\u56de\u6536\u5668\u5728\u8fd9\u6bb5\u65f6\u95f4STW\uff08Stop-The-World\uff09\u7684\u603b\u65f6\u95f4\u4e3a 0.10 + 3.77 = 3.87 \u79d2\u3002<\/p>\n<p><strong>Gceasy.io \u5206\u6790\u7684\u7ed3\u679c\uff1a<\/strong><\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043943985\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p><strong>\u7591\u95ee1\uff1ayoungGC\u540e\u5806\u5185\u5b58\u56de\u6536\u4e0d\u660e\u663e\uff1f<\/strong><\/p>\n<p>\u540e\u9762\u4f1a\u8ffd\u6eaf\u5230MySQL\u7684\u94fe\u63a5\u6c60\u865a\u5f15\u7528\uff0c\u672c\u6b21GC\u53ea\u80fd\u5148\u5c06\u94fe\u63a5\u5b9e\u4f8bGC\u6389\uff0c \u800c\u7528\u4e8e\u8ffd\u8e2aconnection\u5b9e\u4f8b\u56de\u6536\u7684\u865a\u5f15\u7528\uff0c\u4f1a\u5728\u4e0b\u6b21GC\u624d\u80fd\u88ab\u56de\u6536\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043943986\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p><strong>\u7591\u95ee2\uff1aG1\u7684MaxGCPauseMillis\u662f\u5426\u4e25\u683c\u9075\u5b88\uff0c\u4e3a\u4ec0\u4e48\u6211\u914d\u7f6e\u4e86-XX:MaxGCPauseMillis=100 \u672c\u6b21gc\u65f6\u95f4\u8fd8\u662f\u8fbe\u5230\u4e863\u79d2\u4ee5\u4e0a\uff1f<\/strong><\/p>\n<p>G1 \u7684\u00a0<code>-XX:MaxGCPauseMillis<\/code>\u00a0\u53c2\u6570\u8868\u793a G1 GC \u7684\u6700\u5927 STW \u65f6\u95f4\uff0c\u5373\u5982\u679c\u5355\u6b21 GC \u6682\u505c\u65f6\u95f4\u8d85\u8fc7\u8be5\u503c\uff0c\u5219 G1 \u4f1a\u5c3d\u53ef\u80fd\u5730\u8c03\u6574\u5176\u884c\u4e3a\u4ee5\u8fbe\u5230\u8be5\u76ee\u6807\u3002\u4f46\u662f\u8bf7\u6ce8\u610f\uff0c\u8be5\u53c2\u6570\u662f\u4e00\u4e2a\u6307\u5bfc\u6027\u7684\u53c2\u6570\uff0c\u4e0d\u80fd\u4fdd\u8bc1\u7edd\u5bf9\u7cbe\u5ea6\u3002<\/p>\n<p>\u5728\u5b9e\u9645\u5e94\u7528\u4e2d\uff0c\u7531\u4e8e\u5e94\u7528\u7a0b\u5e8f\u548c\u7cfb\u7edf\u7684\u8d1f\u8f7d\u60c5\u51b5\u3001\u5806\u5185\u5b58\u5927\u5c0f\u7b49\u56e0\u7d20\u7684\u5f71\u54cd\uff0cGC \u7684\u53d1\u751f\u548c STW \u65f6\u95f4\u90fd\u53ef\u80fd\u4f1a\u51fa\u73b0\u4e00\u5b9a\u7a0b\u5ea6\u7684\u6ce2\u52a8\u548c\u4e0d\u786e\u5b9a\u6027\u3002\u56e0\u6b64\uff0c\u5355\u6b21 GC \u6682\u505c\u65f6\u95f4\u8d85\u8fc7\u00a0<code>-XX:MaxGCPauseMillis<\/code>\u00a0\u914d\u7f6e\u503c\u662f\u6709\u53ef\u80fd\u53d1\u751f\u7684\uff0c\u800c\u4e14\u8fd9\u79cd\u60c5\u51b5\u5728\u9ad8\u8d1f\u8f7d\u6216\u5806\u5185\u5b58\u4f7f\u7528\u8f83\u9ad8\u65f6\u66f4\u5bb9\u6613\u51fa\u73b0\u3002<\/p>\n<p><strong>\u7591\u95ee3\uff1a\u76d1\u63a7\u4e2d\u4e3a\u5565\u51fa\u73b0\u4e86\u591a\u6b21mixed GC\uff0c \u800c\u4e14\u95f4\u9694\u8fd8\u5982\u6b64\u7684\u77ed<\/strong><\/p>\n<p>-XX:G1MixedGCCountTarget\uff0c\u9ed8\u8ba4\u4e3a8\uff0c\u8fd9\u4e2a\u53c2\u6570\u6807\u8bc6\u6700\u540e\u7684\u6df7\u5408\u56de\u6536\u9636\u6bb5\u4f1a\u6267\u884c8\u6b21\uff0c\u4e00\u6b21\u53ea\u56de\u6536\u6389\u4e00\u90e8\u5206\u7684Region\uff0c\u7136\u540e\u7cfb\u7edf\u7ee7\u7eed\u8fd0\u884c\uff0c\u8fc7\u4e00\u5c0f\u6bb5\u65f6\u95f4\u4e4b\u540e\uff0c\u53c8\u518d\u6b21\u8fdb\u884c\u6df7\u5408\u56de\u6536\uff0c\u91cd\u590d8\u6b21\u3002\u6267\u884c\u8fd9\u79cd\u95f4\u65ad\u7684\u6df7\u5408\u56de\u6536\uff0c\u5c31\u53ef\u4ee5\u628a\u6bcf\u6b21\u7684\u6df7\u5408\u56de\u6536\u65f6\u95f4\u63a7\u5236\u5728\u6211\u4eec\u9700\u8981\u7684\u505c\u987f\u65f6\u95f4\u4e4b\u5185\u4e86\uff0c\u540c\u65f6\u8fbe\u5230\u5783\u573e\u6e05\u7406\u7684\u6548\u679c\u3002\u6e05\u7406\u4e86 7 \u6b21\u5c31\u5df2\u7ecf\u6ee1\u8db3\u4e86\u56de\u6536\u6548\u679c\uff0c\u6240\u4ee5\u6ca1\u6709\u7ee7\u7eed mixed GC\u3002<\/p>\n<p>\u4ee5\u4e0a\u662f\u4e3a\u4e86\uff1aMaxGCPauseMillis \u505c\u987f\u65f6\u95f4\u63a7\u5236\u5728\u671f\u671b\u8303\u56f4\u5185\uff0c\u6240\u4ee5\u4f1a\u51fa\u73b0\u591a\u6b21\u95f4\u9694\u5f88\u77ed\u8fde\u7eed\u7684mixed GC.<\/p>\n<h3>dump\u5206\u6790<\/h3>\n<p>\u901a\u8fc7 MAT \u5de5\u5177\u5206\u6790\u53d1\u73b0\uff0c\u7b2c\u4e00\u4e2a\u53ef\u80fd\u7684\u95ee\u9898\u5c31\u662f\uff1acom.mysql.jdbc.NonRegisteringDriver \u5360\u7528\u6bd4\u8f83\u5927\u7684\u5185\u5b58\uff0c\u5982\u4e0b\u56fe\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043943987\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<pre><code>The class com.mysql.jdbc.NonRegisteringDriver, loaded by org.apache.catalina.loader.ParallelWebappClassLoader @ 0x73e8b9a00, occupies 857,532,208 (88.67%) bytes. The memory is accumulated in one instance of java.util.concurrent.ConcurrentHashMap$Node[], loaded by , which occupies 857,529,112 (88.67%) bytes.\n\nKeywords\n\ncom.mysql.jdbc.NonRegisteringDriver\norg.apache.catalina.loader.ParallelWebappClassLoader @ 0x73e8b9a00\njava.util.concurrent.ConcurrentHashMap$Node[]<\/code><\/pre>\n<p>\u00b7\u7136\u540e\u770b\u5927\u5bf9\u8c61\u5217\u8868\uff0cNonRegisteringDriver \u5bf9\u8c61\u786e\u5b9e\u5360\u5185\u5b58\u6bd4\u8f83\u591a\uff0c\u5176\u4e2d\u6210\u5458\u53d8\u91cfconnectionPhantomRefs \u5360\u5185\u5b58\u6700\u591a\uff0c\u91cc\u9762\u5b58\u7684\u662f\u6570\u636e\u5e93\u8fde\u63a5\u7684\u865a\u5f15\u7528\uff0c\u5176\u7c7b\u578b\u662f ConcurrentHashMap&lt;ConnectionPhantomReference, ConnectionPhantomReference&gt;\uff0c\u5360\u6bd4\u5c45\u7136\u670988%\u4e4b\u591a\u3002  <\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000043943988\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p><strong>\u589e\u52a0JVM\u53c2\u6570\uff0c\u6253\u5370\u8be6\u7ec6\u5bf9\u8c61\u56de\u6536\u626b\u63cf\u65e5\u5fd7<\/strong><\/p>\n<p>\u589e\u52a0JVM\u53c2\u6570\uff1a -XX:+PrintReferenceGC\uff0c \u6253\u5370\u5404\u79cd\u5f15\u7528\u5bf9\u8c61\u7684\u8be6\u7ec6\u56de\u6536\u65f6\u95f4\uff1a<\/p>\n<blockquote>\n<p>PrintReferenceGC\u662fJVM\u63d0\u4f9b\u7684\u4e00\u4e2a\u53c2\u6570\uff0c\u7528\u4e8e\u5728\u8fdb\u884c\u5783\u573e\u56de\u6536\u65f6\u6253\u5370\u5f15\u7528\u5904\u7406\u76f8\u5173\u4fe1\u606f\u3002\u5f53\u542f\u7528\u8be5\u53c2\u6570\u540e\uff0cJVM\u4f1a\u5728\u6bcf\u6b21\u8fdb\u884c\u5783\u573e\u56de\u6536\u65f6\u5c06\u4e00\u4e9b\u6709\u5173\u5f15\u7528\u5904\u7406\uff08Reference Processing\uff09\u7684\u4fe1\u606f\u8f93\u51fa\u5230\u6807\u51c6\u8f93\u51fa\u6216\u6307\u5b9a\u7684\u65e5\u5fd7\u6587\u4ef6\u4e2d\u3002<\/p>\n<p>\u5177\u4f53\u6765\u8bf4\uff0cPrintReferenceGC\u53c2\u6570\u53ef\u5e2e\u52a9\u5f00\u53d1\u4eba\u5458\u548c\u7cfb\u7edf\u7ba1\u7406\u5458\u66f4\u597d\u5730\u4e86\u89e3\u5e94\u7528\u7a0b\u5e8f\u4e2d\u5404\u79cd\u7c7b\u578b\u5f15\u7528\u88ab\u5904\u7406\u7684\u60c5\u51b5\uff0c\u5305\u62ecSoft Reference\u3001Weak Reference\u3001Phantom Reference\u7b49\u3002\u8fd9\u4e9b\u4fe1\u606f\u5bf9\u4e8e\u8bca\u65ad\u5185\u5b58\u6cc4\u6f0f\u548c\u8c03\u6574\u5783\u573e\u56de\u6536\u5668\u6027\u80fd\u975e\u5e38\u6709\u7528\u3002<\/p>\n<\/blockquote>\n<p>\u6253\u5370\u7684\u8be6\u7ec6\u7684gc\u65e5\u5fd7\u5982\u4e0b\uff1a<\/p>\n<pre><code>2023-06-04T10:28:52.886+0800: 24397.548: [GC concurrent-root-region-scan-start]\n2023-06-04T10:28:52.941+0800: 24397.602: [GC concurrent-root-region-scan-end, 0.0545027 secs]\n2023-06-04T10:28:52.941+0800: 24397.602: [GC concurrent-mark-start]\n2023-06-04T10:28:53.198+0800: 24397.859: [GC concurrent-mark-end, 0.2565503 secs]\n2023-06-04T10:28:53.199+0800: 24397.860: [GC remark 2023-06-04T10:28:53.199+0800: 24397.860: [Finalize Marking, 0.0004169 secs] 2023-06-04T10:28:53.199+0800: 24397.861: [GC ref-proc2023-06-04T10:28:53.199+0800: 24397.861: [SoftReference, 9247 refs, 0.0035753 secs]2023-06-04T10:28:53.203+0800: 24397.864: [WeakReference, 963 refs, 0.0003121 secs]2023-06-04T10:28:53.203+0800: 24397.865: [FinalReference, 60971 refs, 0.0693649 secs]2023-06-04T10:28:53.273+0800: 24397.934: [PhantomReference, 49828 refs, 20 refs, 4.5339260 secs]2023-06-04T10:28:57.807+0800: 24402.468: [JNI Weak Reference, 0.0000755 secs], 4.6213645 secs] 2023-06-04T10:28:57.821+0800: 24402.482: [Unloading, 0.0332897 secs], 4.6620392 secs]\n [Times: user=4.60 sys=0.31, real=4.67 secs] \n2023-06-04T10:28:57.863+0800: 24402.524: [GC cleanup 4850M-&gt;4850M(9984M), 0.0031413 secs]\n [Times: user=0.01 sys=0.01, real=0.00 secs] \n{Heap before GC invocations=68 (full 0):\n garbage-first heap   total 10223616K, used 7883923K [0x0000000570000000, 0x00000005720009c0, 0x00000007e0000000)\n  region size 32768K, 98 young (3211264K), 8 survivors (262144K)\n Metaspace       used 111742K, capacity 114304K, committed 114944K, reserved 1150976K\n  class space    used 12694K, capacity 13362K, committed 13568K, reserved 1048576K<\/code><\/pre>\n<p>\u7ffb\u8bd1\u65e5\u5fd7\u5185\u5bb9\u5982\u4e0b\uff1a<\/p>\n<pre><code>2023-06-04T10:28:52.886+0800: 24397.548: [GC concurrent-root-region-scan-start]\uff1a\u5f00\u59cb\u626b\u63cf\u5e76\u53d1\u6839\u533a\u57df\u3002\n2023-06-04T10:28:52.941+0800: 24397.602: [GC concurrent-root-region-scan-end, 0.0545027 secs]\uff1a\u5e76\u53d1\u6839\u533a\u57df\u626b\u63cf\u7ed3\u675f\uff0c\u6301\u7eed\u65f6\u95f4\u4e3a0.0545027\u79d2\u3002\n2023-06-04T10:28:52.941+0800: 24397.602: [GC concurrent-mark-start]\uff1a\u5f00\u59cb\u5e76\u53d1\u6807\u8bb0\u8fc7\u7a0b\u3002\n2023-06-04T10:28:53.198+0800: 24397.859: [GC concurrent-mark-end, 0.2565503 secs]\uff1a\u5e76\u53d1\u6807\u8bb0\u8fc7\u7a0b\u7ed3\u675f\uff0c\u6301\u7eed\u65f6\u95f4\u4e3a0.2565503\u79d2\u3002\n2023-06-04T10:28:53.199+0800: 24397.860: [GC remark]: G1\u6267\u884cremark\u9636\u6bb5\u3002\n2023-06-04T10:28:53.199+0800: 24397.860: [Finalize Marking, 0.0004169 secs]\uff1a\u6807\u8bb0finalize\u961f\u5217\u4e2d\u5f85\u5904\u7406\u5bf9\u8c61\uff0c\u6301\u7eed\u65f6\u95f4\u4e3a0.0004169\u79d2\u3002\n2023-06-04T10:28:53.199+0800: 24397.861: [GC ref-proc]: \u8fdb\u884c\u5f15\u7528\u5904\u7406\u3002\n2023-06-04T10:28:53.199+0800: 24397.861: [SoftReference, 9247 refs, 0.0035753 secs]\uff1a\u5904\u7406\u8f6f\u5f15\u7528\uff0c\u6301\u7eed\u65f6\u95f4\u4e3a0.0035753\u79d2\u3002\n2023-06-04T10:28:53.203+0800: 24397.864: [WeakReference, 963 refs, 0.0003121 secs]\uff1a\u5904\u7406\u5f31\u5f15\u7528\uff0c\u6301\u7eed\u65f6\u95f4\u4e3a0.0003121\u79d2\u3002\n2023-06-04T10:28:53.203+0800: 24397.865: [FinalReference, 60971 refs, 0.0693649 secs]\uff1a\u5904\u7406\u865a\u5f15\u7528\uff0c\u6301\u7eed\u65f6\u95f4\u4e3a0.0693649\u79d2\u3002\n2023-06-04T10:28:53.273+0800: 24397.934: [PhantomReference, 49828 refs, 20 refs, 4.5339260 secs]\uff1a\u5904\u7406final reference\u4e2d\u7684phantom\u5f15\u7528\uff0c\u6301\u7eed\u65f6\u95f4\u4e3a4.5339260\u79d2\u3002\n2023-06-04T10:28:57.807+0800: 24402.468: [JNI Weak Reference, 0.0000755 secs]\uff1a\u5904\u7406JNI weak\u5f15\u7528\uff0c\u6301\u7eed\u65f6\u95f4\u4e3a0.0000755\u79d2\u3002\n2023-06-04T10:28:57.821+0800: 24402.482: [Unloading, 0.0332897 secs]\uff1a\u5378\u8f7d\u65e0\u7528\u7684\u7c7b\uff0c\u6301\u7eed\u65f6\u95f4\u4e3a0.0332897\u79d2\u3002\n[Times: user=4.60 sys=0.31, real=4.67 secs]\uff1a\u5783\u573e\u56de\u6536\u7684\u65f6\u95f4\u4fe1\u606f\uff0cuser\u8868\u793a\u7528\u6237\u6001CPU\u65f6\u95f4\u3001sys\u8868\u793a\u5185\u6838\u6001CPU\u65f6\u95f4\u3001real\u8868\u793a\u5b9e\u9645\u8fd0\u884c\u65f6\u95f4\u3002\n2023-06-04T10:28:57.863+0800: 24402.524: [GC cleanup 4850M-&gt;4850M(9984M), 0.0031413 secs]\uff1a\u6267\u884ccleanup\u64cd\u4f5c\uff0c\u5c06\u5806\u5927\u5c0f\u4ece4850M\u8c03\u6574\u4e3a4850M\uff0c\u6301\u7eed\u65f6\u95f4\u4e3a0.0031413\u79d2\u3002<\/code><\/pre>\n<p><strong>\u5176\u4e2dPhantomReference\u8017\u65f6\u6700\u957f\uff1a<\/strong><\/p>\n<p>2023-06-04T10:28:53.273+0800: 24397.934: [PhantomReference, 49828 refs, 20 refs, 4.5339260 secs]\uff1a\u5904\u7406final reference\u4e2d\u7684phantom\u5f15\u7528\uff0c\u6301\u7eed\u65f6\u95f4\u4e3a4.5339260\u79d2\u3002<\/p>\n<h3>\u6e90\u7801\u8ffd\u8e2a<\/h3>\n<h4>MYSQL driver\u76f8\u5173<\/h4>\n<blockquote><p>\u6ce8\u610f\uff0c\u672c\u6e90\u7801\u57fa\u4e8e\u5f53\u524d\u4f9d\u8d56\u7684mysql-connector-java-5.1.30.jar, \u5404\u7248\u672c\u7684\u4ee3\u7801\u6709\u4e00\u5b9a\u5dee\u5f02\u6027\u8d28;<\/p><\/blockquote>\n<p>\u6d89\u53caMySQL\u521b\u5efa\u8fde\u63a5\u6c60\u7684\u5730\u65b9\u4e3a\uff1acom.mysql.jdbc.NonRegisteringDriver#connect\u65b9\u6cd5:<\/p>\n<pre><code>  public Connection connect(String url, Properties info) throws SQLException {\n      \/\/...\u7701\u7565\u90e8\u5206\u4ee3\u7801\n\n        Properties props = null;\n        if ((props = this.parseURL(url, info)) == null) {\n            return null;\n        } else if (!&quot;1&quot;.equals(props.getProperty(&quot;NUM_HOSTS&quot;))) {\n            return this.connectFailover(url, info);\n        } else {\n            try {\n                \/\/  \u83b7\u53d6\u8fde\u63a5\u4e3b\u8981\u5728\u8fd9\u91cc\n                com.mysql.jdbc.Connection newConn = ConnectionImpl.getInstance(this.host(props), this.port(props), props, this.database(props), url);\n                return newConn;\n            } catch (SQLException var6) {\n                throw var6;\n            } catch (Exception var7) {\n                SQLException sqlEx = SQLError.createSQLException(Messages.getString(&quot;NonRegisteringDriver.17&quot;) + var7.toString() + Messages.getString(&quot;NonRegisteringDriver.18&quot;), &quot;08001&quot;, (ExceptionInterceptor)null);\n                sqlEx.initCause(var7);\n                throw sqlEx;\n            }\n        }\n    }<\/code><\/pre>\n<p><code>com.mysql.jdbc.ConnectionImpl<\/code>\u6784\u9020\u5668\u6bd4\u8f83\u957f\uff0c\u5728\u5b8c\u6210\u53c2\u6570\u6784\u5efa\u540e\uff0c\u5728\u5176\u7ed3\u5c3e\u5904\uff0c\u53d1\u73b0\u5b83\u8c03\u7528\u4e86<code>NonRegisteringDriver.trackConnection(this)<\/code>\u3002<\/p>\n<pre><code>public ConnectionImpl(String hostToConnectTo, int portToConnectTo, Properties info, String databaseToConnectTo, String url) throws SQLException {\n    ......\n    NonRegisteringDriver.trackConnection(this);\n}<\/code><\/pre>\n<p>\u5176\u4e2d\u8ffd\u8e2a\u4efb\u52a1\u7684\u6ce8\u518c\u5982\u4e0b\uff1a\u8fd9\u6bb5MySQL driver\u6e90\u7801\u7684\u4f5c\u7528\u662f\u5b9e\u73b0\u5bf9MySQL\u6570\u636e\u5e93\u8fde\u63a5\u7684\u8ddf\u8e2a\u3002<\/p>\n<pre><code> public class NonRegisteringDriver {\n \n   \/\/\u7701\u7565\u90e8\u5206\u4ee3\u7801...\n\n\n   \/\/ \u8fde\u63a5\u865a\u5f15\u7528\u6307\u5411map\u7684\u5bb9\u5668\u58f0\u660e\n  protected static final ConcurrentHashMap&lt;ConnectionPhantomReference, ConnectionPhantomReference&gt; connectionPhantomRefs = new ConcurrentHashMap();\n\n\n  \/\/ \u5c06\u8fde\u63a5\u653e\u5165\u8ffd\u8e2a\u5bb9\u5668\u4e2d\n   protected static void trackConnection(com.mysql.jdbc.Connection newConn) {\n        ConnectionPhantomReference phantomRef = new ConnectionPhantomReference((ConnectionImpl)newConn, refQueue);\n        connectionPhantomRefs.put(phantomRef, phantomRef);\n    }\n    \n   \n     \/\/\u7701\u7565\u90e8\u5206\u4ee3\u7801...\n   }<\/code><\/pre>\n<p>\u7b2c\u4e00\u884c\u4ee3\u7801\u58f0\u660e\u4e86\u4e00\u4e2a\u540d\u4e3a<code>connectionPhantomRefs<\/code>\u7684<code>ConcurrentHashMap<\/code>\u5bb9\u5668\uff0c\u8be5\u5bb9\u5668\u7528\u4e8e\u5b58\u50a8<code>ConnectionPhantomReference<\/code>\u5b9e\u4f8b\u3002<\/p>\n<p>\u7b2c\u4e8c\u4e2a\u65b9\u6cd5<code>trackConnection<\/code>\u7684\u4f5c\u7528\u662f\u5c06\u65b0\u8fde\u63a5\u6dfb\u52a0\u5230<code>connectionPhantomRefs<\/code>\u6620\u5c04\u4e2d\u3002\u5b83\u63a5\u53d7\u4e00\u4e2a<code>com.mysql.jdbc.Connection<\/code>\u5bf9\u8c61\u4f5c\u4e3a\u53c2\u6570\uff0c\u521b\u5efa\u4e00\u4e2a\u65b0\u7684<code>ConnectionPhantomReference<\/code>\u5b9e\u4f8b\uff0c\u5e76\u4f7f\u7528\u5b83\u548c\u5f15\u7528\u961f\u5217\uff08<code>refQueue<\/code>\uff09\u5c06\u5176\u6dfb\u52a0\u5230<code>connectionPhantomRefs<\/code>\u6620\u5c04\u4e2d\u3002<\/p>\n<p>\u603b\u7684\u6765\u8bf4\uff0c\u8fd9\u4e24\u4e2a\u4ee3\u7801\u7247\u6bb5\u65e8\u5728\u901a\u8fc7\u4f7f\u7528\u865a\u5f15\u7528\u6765\u5b9e\u73b0\u8ddf\u8e2a\u8fde\u63a5\u5230MySQL\u6570\u636e\u5e93\u7684\u673a\u5236\u3002\u865a\u5f15\u7528\u7528\u4e8e\u8ddf\u8e2a\u5df2\u88abJVM\u5783\u573e\u56de\u6536\u7684\u5bf9\u8c61\uff0c\u5141\u8bb8\u7a0b\u5e8f\u5728\u5bf9\u8c61\u4ece\u5185\u5b58\u4e2d\u5220\u9664\u540e\u6267\u884c\u7279\u5b9a\u4efb\u52a1\u3002<\/p>\n<h5>\u8fde\u63a5\u865a\u5f15\u7528\u4e3a\u9759\u6001\u5185\u90e8\u7c7b<\/h5>\n<p>\u8fd9\u6bb5\u4ee3\u7801\u662f MySQL \u9a71\u52a8\u7a0b\u5e8f\u7684\u4e00\u90e8\u5206\uff0c\u7528\u4e8e\u6e05\u7406\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\u5e76\u786e\u4fdd\u5728 MySQL \u8fde\u63a5\u5bf9\u8c61\u88ab\u5783\u573e\u56de\u6536\u65f6\u91ca\u653e\u8fd9\u4e9b\u8d44\u6e90\u3002<\/p>\n<pre><code>    static class ConnectionPhantomReference extends PhantomReference&lt;ConnectionImpl&gt; {\n        private NetworkResources io;\n\n        ConnectionPhantomReference(ConnectionImpl connectionImpl, ReferenceQueue&lt;ConnectionImpl&gt; q) {\n            super(connectionImpl, q);\n\n            try {\n                this.io = connectionImpl.getIO().getNetworkResources();\n            } catch (SQLException var4) {\n            }\n\n        }\n\n        void cleanup() {\n            if (this.io != null) {\n                try {\n                    this.io.forceClose();\n                } finally {\n                    this.io = null;\n                }\n            }\n\n        }\n    }<\/code><\/pre>\n<p>\u8fd9\u6bb5 MySQL driver \u6e90\u7801\u4e2d\u7684\u00a0<code>ConnectionPhantomReference<\/code>\u00a0\u7c7b\u662f\u4e00\u4e2a\u7ee7\u627f\u81ea\u00a0<code>PhantomReference&lt;ConnectionImpl&gt;<\/code>\u00a0\u7684\u9759\u6001\u5185\u90e8\u7c7b\uff0c\u5176\u4e2d ConnectionImpl \u662f MySQL \u8fde\u63a5\u7684\u5b9e\u73b0\u7c7b\u3002\u8be5\u7c7b\u7684\u4f5c\u7528\u662f\u5728\u8fde\u63a5\u5bf9\u8c61\u88ab\u5783\u573e\u56de\u6536\u65f6\u6e05\u7406\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\u3002<\/p>\n<p><code>ConnectionPhantomReference<\/code>\u00a0\u6784\u9020\u51fd\u6570\u63a5\u53d7\u00a0<code>ConnectionImpl<\/code>\u00a0\u5bf9\u8c61\u548c\u4e00\u4e2a\u5f15\u7528\u961f\u5217\u4f5c\u4e3a\u53c2\u6570\uff0c\u5e76\u8c03\u7528\u7236\u7c7b\u00a0<code>PhantomReference<\/code>\u00a0\u7684\u6784\u9020\u51fd\u6570\u6765\u521b\u5efa\u865a\u5f15\u7528\u3002\u5b83\u8fd8\u901a\u8fc7\u8c03\u7528\u00a0<code>ConnectionImpl<\/code>\u00a0\u7684\u00a0<code>getIO().getNetworkResources()<\/code>\u00a0\u65b9\u6cd5\u83b7\u53d6\u4e0e\u8fde\u63a5\u5173\u8054\u7684\u7f51\u7edc\u8d44\u6e90\u3002\u5982\u679c\u83b7\u53d6\u5931\u8d25\uff0c\u5219\u4e0d\u4f1a\u629b\u51fa\u5f02\u5e38\u3002<\/p>\n<p><code>cleanup()<\/code>\u00a0\u65b9\u6cd5\u7528\u4e8e\u5728\u8fde\u63a5\u5bf9\u8c61\u88ab\u5783\u573e\u56de\u6536\u540e\u6e05\u7406\u7f51\u7edc\u8d44\u6e90\u3002\u5b83\u68c0\u67e5\u00a0<code>io<\/code>\u00a0\u5c5e\u6027\u662f\u5426\u4e3a\u7a7a\uff0c\u5982\u679c\u4e0d\u4e3a\u7a7a\uff0c\u5219\u8c03\u7528\u00a0<code>forceClose()<\/code>\u00a0\u65b9\u6cd5\u6765\u5f3a\u5236\u5173\u95ed\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\uff0c\u6700\u7ec8\u5c06\u00a0<code>io<\/code>\u00a0\u5c5e\u6027\u8bbe\u7f6e\u4e3a null\u3002\u6574\u4e2a\u8fc7\u7a0b\u786e\u4fdd\u8fde\u63a5\u5bf9\u8c61\u88ab\u5783\u573e\u56de\u6536\u65f6\uff0c\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\u4e5f\u88ab\u6b63\u786e\u5730\u91ca\u653e\u3002<\/p>\n<h5>MySQL\u4e3a\u4ec0\u4e48\u8981\u4f7f\u7528\u865a\u5f15\u7528\u6765\u89e3\u51b3IO\u8d44\u6e90\u56de\u6536\u95ee\u9898\uff1f<\/h5>\n<p>MySQL \u4f7f\u7528\u865a\u5f15\u7528\u6765\u89e3\u51b3 IO \u8d44\u6e90\u56de\u6536\u95ee\u9898\uff0c\u4e3b\u8981\u662f\u56e0\u4e3a JDBC \u8fde\u63a5\u5bf9\u8c61\u5728\u5173\u95ed\u8fde\u63a5\u65f6\u65e0\u6cd5\u4fdd\u8bc1\u5176\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\u4f1a\u88ab\u7acb\u5373\u91ca\u653e\u3002\u8fd9\u53ef\u80fd\u4f1a\u5bfc\u81f4\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\u957f\u65f6\u95f4\u5360\u7528\uff0c\u6700\u7ec8\u5bfc\u81f4\u5e94\u7528\u7a0b\u5e8f\u51fa\u73b0\u6027\u80fd\u4e0b\u964d\u6216\u8005\u8d44\u6e90\u8017\u5c3d\u7684\u60c5\u51b5\u3002<\/p>\n<p>\u4f7f\u7528\u865a\u5f15\u7528\u7684\u597d\u5904\u5728\u4e8e\uff0c\u5b83\u5141\u8bb8\u7a0b\u5e8f\u5728\u5bf9\u8c61\u4ece\u5185\u5b58\u4e2d\u5220\u9664\u540e\u6267\u884c\u7279\u5b9a\u4efb\u52a1\u3002 MySQL \u9a71\u52a8\u7a0b\u5e8f\u5229\u7528 Java \u63d0\u4f9b\u7684\u5f15\u7528\u961f\u5217\u673a\u5236\uff0c\u5c06 JDBC \u8fde\u63a5\u5bf9\u8c61\u7684\u865a\u5f15\u7528\u52a0\u5165\u5230\u961f\u5217\u4e2d\u3002\u4e00\u65e6\u8fde\u63a5\u5bf9\u8c61\u88ab\u5783\u573e\u56de\u6536\uff0cJVM \u4f1a\u5c06\u5b83\u52a0\u5165\u5230\u5f15\u7528\u961f\u5217\u4e2d\u7b49\u5f85\u8fdb\u4e00\u6b65\u5904\u7406\u3002\u6b64\u65f6\uff0cMySQL \u9a71\u52a8\u7a0b\u5e8f\u901a\u8fc7\u76d1\u89c6\u5f15\u7528\u961f\u5217\u5e76\u6e05\u7406\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\uff0c\u786e\u4fdd\u8fd9\u4e9b\u8d44\u6e90\u5728\u8fde\u63a5\u5bf9\u8c61\u88ab\u5783\u573e\u56de\u6536\u65f6\u88ab\u6b63\u786e\u5730\u91ca\u653e\uff0c\u4ece\u800c\u907f\u514d\u4e86\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\u957f\u65f6\u95f4\u5360\u7528\u7684\u95ee\u9898\u3002<\/p>\n<p>\u4f7f\u7528\u865a\u5f15\u7528\u7684\u4f18\u70b9\u5728\u4e8e\u53ef\u4ee5\u5b9e\u73b0\u66f4\u7cbe\u7ec6\u7684\u5185\u5b58\u7ba1\u7406\u548c\u8d44\u6e90\u56de\u6536\uff0c\u63d0\u9ad8\u5e94\u7528\u7a0b\u5e8f\u7684\u53ef\u9760\u6027\u548c\u6027\u80fd\u3002<\/p>\n<h5>\u90a3MySQL\u662f\u600e\u6837\u6267\u884c\u6700\u7ec8\u7684IO\u8d44\u6e90\u56de\u6536\u7684\u5462\uff0c\u662f\u4f7f\u7528\u4e86\u5b9a\u65f6\u4efb\u52a1\u8fd8\u662f\u5f02\u6b65\u5b88\u62a4\u7ebf\u7a0b\uff1f<\/h5>\n<p>MySQL \u5728\u6267\u884c\u6700\u7ec8\u7684 IO \u8d44\u6e90\u56de\u6536\u65f6\uff0c\u4f7f\u7528\u4e86\u5f02\u6b65\u5b88\u62a4\u7ebf\u7a0b\u6765\u6e05\u7406\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\u3002<\/p>\n<p>MySQL \u9a71\u52a8\u7a0b\u5e8f\u5c06 JDBC \u8fde\u63a5\u5bf9\u8c61\u7684\u865a\u5f15\u7528\u52a0\u5165\u5230\u5f15\u7528\u961f\u5217\u4e2d\u540e\uff0c\u4f1a\u521b\u5efa\u4e00\u4e2a\u4e13\u95e8\u7684\u5b88\u62a4\u7ebf\u7a0b\u6765\u76d1\u89c6\u8be5\u5f15\u7528\u961f\u5217\u3002\u5f53\u8fde\u63a5\u5bf9\u8c61\u88ab\u5783\u573e\u56de\u6536\u5e76\u52a0\u5165\u5230\u5f15\u7528\u961f\u5217\u4e2d\u540e\uff0c\u5b88\u62a4\u7ebf\u7a0b\u4f1a\u4ece\u5f15\u7528\u961f\u5217\u4e2d\u83b7\u53d6\u8be5\u8fde\u63a5\u5bf9\u8c61\u7684\u865a\u5f15\u7528\uff0c\u5e76\u5728\u540e\u53f0\u7ebf\u7a0b\u4e2d\u6267\u884c\u4e0e\u8fde\u63a5\u76f8\u5173\u7684\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\u6e05\u7406\u5de5\u4f5c\u3002<\/p>\n<p>\u5177\u4f53\u6765\u8bf4\uff0c\u5b88\u62a4\u7ebf\u7a0b\u5728\u6bcf\u6b21\u8fed\u4ee3\u4e2d\u4ece\u5f15\u7528\u961f\u5217\u4e2d\u83b7\u53d6\u4e00\u7ec4\u865a\u5f15\u7528\uff0c\u5e76\u8c03\u7528\u865a\u5f15\u7528\u7684\u00a0<code>cleanup()<\/code>\u00a0\u65b9\u6cd5\u6765\u6e05\u7406\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\u3002\u5982\u679c\u6210\u529f\u6e05\u7406\uff0c\u5219\u5c06\u5176\u4ece\u6620\u5c04\u8868\u4e2d\u5220\u9664\uff1b\u5426\u5219\uff0c\u4fdd\u7559\u865a\u5f15\u7528\u4ee5\u4fbf\u4e0b\u4e00\u6b21\u8fed\u4ee3\u3002<\/p>\n<p>\u7531\u4e8e\u6e05\u7406\u64cd\u4f5c\u662f\u5728\u540e\u53f0\u7ebf\u7a0b\u4e2d\u8fdb\u884c\u7684\uff0c\u56e0\u6b64\u4e0d\u4f1a\u963b\u585e\u5e94\u7528\u7a0b\u5e8f\u7684\u4e3b\u7ebf\u7a0b\u3002\u540c\u65f6\uff0c\u4f7f\u7528\u5f02\u6b65\u5b88\u62a4\u7ebf\u7a0b\u8fd8\u53ef\u4ee5\u907f\u514d\u5b9a\u65f6\u4efb\u52a1\u53ef\u80fd\u5e26\u6765\u7684\u6027\u80fd\u5f00\u9500\u548c\u4e0d\u5fc5\u8981\u7684 CPU \u4f7f\u7528\u7387\u3002<\/p>\n<p>MySQL \u4f7f\u7528\u5f02\u6b65\u5b88\u62a4\u7ebf\u7a0b\u6765\u6267\u884c IO \u8d44\u6e90\u56de\u6536\u5de5\u4f5c\uff0c\u8fd9\u79cd\u65b9\u5f0f\u53ef\u4ee5\u786e\u4fdd\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\u7684\u53ca\u65f6\u91ca\u653e\uff0c\u5e76\u4e14\u4e0d\u4f1a\u5bf9\u5e94\u7528\u7a0b\u5e8f\u7684\u6027\u80fd\u4ea7\u751f\u8d1f\u9762\u5f71\u54cd\u3002<\/p>\n<p>\u4ee5\u4e0b\u662f MySQL \u9a71\u52a8\u7a0b\u5e8f\u4e2d\u6267\u884c IO \u8d44\u6e90\u56de\u6536\u7684\u5b88\u62a4\u7ebf\u7a0b\u7684\u76f8\u5173\u4ee3\u7801\uff1a<\/p>\n<pre><code>public class NonRegisteringDriver implements java.sql.Driver {\n \n\/\/\u7701\u7565\u4ee3\u7801...\n\n\/\/\u5728MySQL driver\u4e2d\u5b88\u62a4\u7ebf\u7a0b\u521b\u5efa\u53ca\u542f\u52a8...\nstatic {\n        AbandonedConnectionCleanupThread referenceThread = new AbandonedConnectionCleanupThread();\n        referenceThread.setDaemon(true);\n        referenceThread.start();\n    }\n  \n  \/\/\u7701\u7565\u4ee3\u7801...\n}\n\npublic class AbandonedConnectionCleanupThread extends Thread {\n    private static boolean running = true;\n    private static Thread threadRef = null;\n\n    public AbandonedConnectionCleanupThread() {\n        super(&quot;Abandoned connection cleanup thread&quot;);\n    }\n\n    public void run() {\n        threadRef = this;\n        while (running) {\n            try {\n                Reference&lt;? extends ConnectionImpl&gt; ref = NonRegisteringDriver.refQueue.remove(100);\n                if (ref != null) {\n                    try {\n                        ((ConnectionPhantomReference) ref).cleanup();\n                    } finally {\n                        NonRegisteringDriver.connectionPhantomRefs.remove(ref);\n                    }\n                }\n\n            } catch (Exception ex) {\n                \/\/ no where to really log this if we're static\n            }\n        }\n    }\n\n    public static void shutdown() throws InterruptedException {\n        running = false;\n        if (threadRef != null) {\n            threadRef.interrupt();\n            threadRef.join();\n            threadRef = null;\n        }\n    }\n\n}<\/code><\/pre>\n<p>\u8fd9\u6bb5\u4ee3\u7801\u662f MySQL \u9a71\u52a8\u7a0b\u5e8f\u4e2d\u7684\u4e00\u4e2a\u7c7b\u00a0<code>AbandonedConnectionCleanupThread<\/code>\uff0c\u8be5\u7c7b\u7ee7\u627f\u81ea Java \u7684\u00a0<code>Thread<\/code>\u00a0\u7c7b\u3002\u5176\u4f5c\u7528\u662f\u5b9a\u671f\u6e05\u7406\u8fde\u63a5\u5bf9\u8c61\u7684\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\uff0c\u9632\u6b62\u51fa\u73b0\u8d44\u6e90\u6cc4\u9732\u548c\u5185\u5b58\u6ea2\u51fa\u7b49\u95ee\u9898\u3002\u5728\u8be5\u7c7b\u7684\u00a0<code>run()<\/code>\u00a0\u65b9\u6cd5\u4e2d\uff0c\u5faa\u73af\u68c0\u67e5\u662f\u5426\u6709\u865a\u5f15\u7528\u9700\u8981\u6e05\u7406\u3002\u5982\u679c\u5b58\u5728\uff0c\u5219\u8c03\u7528\u00a0<code>cleanup()<\/code>\u00a0\u65b9\u6cd5\u6765\u6e05\u7406\u865a\u5f15\u7528\u6240\u5173\u8054\u7684\u5e95\u5c42\u7f51\u7edc\u8d44\u6e90\uff0c\u5e76\u4ece\u00a0<code>NonRegisteringDriver.connectionPhantomRefs<\/code>\u00a0\u6620\u5c04\u4e2d\u5220\u9664\u8be5\u865a\u5f15\u7528\u3002<\/p>\n<p>\u5728 MySQL \u9a71\u52a8\u7a0b\u5e8f\u4e2d\uff0c<code>connectionPhantomRefs<\/code>\u00a0\u6620\u5c04\u8868\u7684\u952e\u548c\u503c\u90fd\u662f\u00a0<code>ConnectionPhantomReference<\/code>\u00a0\u7c7b\u578b\u7684\u5bf9\u8c61\uff0c\u5373\u4f7f\u7528\u540c\u4e00\u4e2a\u5bf9\u8c61\u4f5c\u4e3a\u952e\u548c\u503c\u3002<\/p>\n<p>\u8fd9\u6837\u505a\u7684\u4e3b\u8981\u539f\u56e0\u662f\uff0c\u5728\u865a\u5f15\u7528\u88ab\u52a0\u5165\u5230\u5f15\u7528\u961f\u5217\u4e2d\u65f6\uff0c\u9700\u8981\u4ece\u6620\u5c04\u8868\u4e2d\u5220\u9664\u5bf9\u5e94\u7684\u865a\u5f15\u7528\u3002\u5982\u679c\u5c06\u865a\u5f15\u7528\u5bf9\u8c61\u4f5c\u4e3a\u952e\uff0c\u90a3\u4e48\u5728\u5220\u9664\u865a\u5f15\u7528\u65f6\uff0c\u9700\u8981\u904d\u5386\u6574\u4e2a\u6620\u5c04\u8868\u624d\u80fd\u627e\u5230\u8be5\u865a\u5f15\u7528\u5bf9\u8c61\u5e76\u5c06\u5176\u5220\u9664\uff0c\u8fd9\u4f1a\u9020\u6210\u4e0d\u5fc5\u8981\u7684\u6027\u80fd\u5f00\u9500\u3002<\/p>\n<p>\u76f8\u53cd\uff0c\u5982\u679c\u5c06\u865a\u5f15\u7528\u5bf9\u8c61\u4f5c\u4e3a\u503c\uff0c\u90a3\u4e48\u53ea\u9700\u8981\u4f7f\u7528\u8be5\u865a\u5f15\u7528\u5bf9\u8c61\u81ea\u8eab\u6765\u5220\u9664\u6620\u5c04\u8868\u4e2d\u7684\u6761\u76ee\uff0c\u5c31\u53ef\u4ee5\u63d0\u9ad8\u5220\u9664\u6548\u7387\u3002\u5728\u00a0<code>trackConnection()<\/code>\u00a0\u65b9\u6cd5\u4e2d\uff0c\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u00a0<code>ConnectionPhantomReference<\/code>\u00a0\u5bf9\u8c61\uff0c\u5e76\u5c06\u5176\u4f5c\u4e3a\u952e\u548c\u503c\u5b58\u50a8\u5230\u00a0<code>connectionPhantomRefs<\/code>\u00a0\u6620\u5c04\u8868\u4e2d\u3002\u8fd9\u6837\uff0c\u5728\u865a\u5f15\u7528\u88ab\u52a0\u5165\u5230\u5f15\u7528\u961f\u5217\u4e2d\u65f6\uff0c\u53ea\u9700\u4ece\u6620\u5c04\u8868\u4e2d\u5220\u9664\u8be5\u865a\u5f15\u7528\u5bf9\u8c61\u81ea\u8eab\u5373\u53ef\uff0c\u65e0\u9700\u904d\u5386\u6574\u4e2a\u6620\u5c04\u8868\u3002<\/p>\n<p>\u603b\u4e4b\uff0c\u4f7f\u7528\u540c\u4e00\u4e2a\u5bf9\u8c61\u4f5c\u4e3a\u6620\u5c04\u8868\u7684\u952e\u548c\u503c\uff0c\u53ef\u4ee5\u66f4\u6709\u6548\u5730\u5220\u9664\u6620\u5c04\u8868\u4e2d\u7684\u6761\u76ee\uff0c\u63d0\u9ad8\u6027\u80fd\u548c\u6548\u7387\u3002<\/p>\n<p><strong>PS: java.lang.ref.ReferenceQueue#remove(long) \u4ecb\u7ecd<\/strong><\/p>\n<p><code>java.lang.ref.ReferenceQueue#remove(long)<\/code>\u00a0\u65b9\u6cd5\u7684\u4f5c\u7528\u662f\u4ece\u961f\u5217\u4e2d\u79fb\u9664\u5df2\u7ecf\u88ab\u56de\u6536\u7684\u00a0<code>Reference<\/code>\u00a0\u5bf9\u8c61\uff0c\u82e5\u961f\u5217\u4e2d\u6ca1\u6709\u4efb\u4f55\u5143\u7d20\uff0c\u5219\u8be5\u65b9\u6cd5\u4f1a\u4e00\u76f4\u7b49\u5f85\u76f4\u5230\u6709\u5143\u7d20\u52a0\u5165\u6216\u8005\u7ecf\u8fc7\u6307\u5b9a\u65f6\u95f4\u540e\u8fd4\u56de null\u3002<\/p>\n<p>\u8be5\u65b9\u6cd5\u7684\u53c2\u6570\u4e3a\u8d85\u65f6\u65f6\u95f4\uff0c\u5355\u4f4d\u4e3a\u6beb\u79d2\u3002\u5982\u679c\u5728\u6307\u5b9a\u7684\u8d85\u65f6\u65f6\u95f4\u5185\u6ca1\u6709\u5143\u7d20\u52a0\u5165\u961f\u5217\uff0c\u5219\u8be5\u65b9\u6cd5\u8fd4\u56de null\u3002\u5982\u679c\u8d85\u65f6\u65f6\u95f4\u4e3a 0\uff0c\u5219\u8be5\u65b9\u6cd5\u7acb\u5373\u8fd4\u56de\uff0c\u5e76\u4e14\u4e0d\u4f1a\u7b49\u5f85\u4efb\u4f55\u5143\u7d20\u52a0\u5165\u961f\u5217\u3002<\/p>\n<p>\u901a\u5e38\u60c5\u51b5\u4e0b\uff0c\u7a0b\u5e8f\u4e0d\u9700\u8981\u8c03\u7528\u8fd9\u4e2a\u65b9\u6cd5\u3002Java \u865a\u62df\u673a\u4f1a\u81ea\u52a8\u8c03\u7528\u8be5\u65b9\u6cd5\u6765\u5904\u7406\u5df2\u7ecf\u88ab\u56de\u6536\u7684\u5bf9\u8c61\u3002\u53ea\u6709\u5728\u7279\u5b9a\u7684\u60c5\u51b5\u4e0b\uff0c\u5982\u624b\u52a8\u7ba1\u7406\u5185\u5b58\u65f6\u624d\u9700\u8981\u624b\u52a8\u8c03\u7528\u8be5\u65b9\u6cd5\u3002<\/p>\n<p>\u8fd9\u91cc\u4f7f\u7528java.lang.ref.ReferenceQueue\u4e3b\u8981\u4f5c\u7528\u662f\u5728Connection\u88ab\u5783\u573e\u56de\u6536\u5668\u56de\u6536\u540e\uff0c \u80fd\u901a\u8fc7remove(timeout) \u83b7\u53d6\u5df2\u7ecf\u88ab\u56de\u6536\u7684\u5f15\u7528\u961f\u5217\uff0c\u7136\u540e\u8fdb\u884c\u540e\u7f6e\u5904\u7406\u3002<\/p>\n<h3>\u63a8\u65ad<\/h3>\n<p>\u56e0\u4e3a\u76ee\u524d\u5728NonRegisteringDriver\u7684\u9759\u6001\u6210\u5458\u53d8\u91cf\uff1aconnectionPhantomRefs, \u6709\u51e0\u4e07\u4e2a\u5bf9\u8c61\uff0c \u8bc1\u660e\u5728\u8fd9\u6bb5\u65f6\u95f4\u79ef\u7d2f\u4e86\u5927\u91cf\u7684\u6570\u636e\u5e93\u94fe\u63a5connection\u5b9e\u4f8b\u8fdb\u5165\u4ee5\u4e0b\u751f\u547d\u5468\u671f\uff1a<\/p>\n<blockquote><p>\u521b\u5efa &#8211;&gt; \u95f2\u7f6e &#8212;&gt; \u56de\u6536;<\/p><\/blockquote>\n<p><strong>\u7591\u70b91\uff1a<\/strong><\/p>\n<p>\u56e0\u4e3a\u524d\u9762\u8fde\u63a5\u95f2\u7f6e\u65f6\u95f4\u4e3a<code>db.minEvictableIdleTimeMillis<\/code>=180000\uff083\u5206\u949f\uff09\uff0c \u53ef\u80fd\u662f\u9020\u6210\u95ee\u9898\u7684\u5173\u952e\u3002\u6b63\u5e38\u7684MySQL\u94fe\u63a5\u95f2\u7f6e\u65f6\u95f4\u9ed8\u8ba4\u4e3a8\u5c0f\u65f6\u3002<\/p>\n<p><strong>\u7591\u70b92\uff1a<\/strong><\/p>\n<p>\u6b64\u5916\uff0c\u56e0\u4e3a\u8be5\u5e94\u7528\u6709\u591a\u4e2a\u6570\u636e\u6e90\uff0c\u4e14\u90e8\u5206\u6570\u636e\u8fdb\u884c\u4e86\u5206\u5e93\uff0c\u5bfc\u81f4\u548c\u6570\u636e\u5e93\u7684\u8fde\u63a5\u6570\u8f83\u591a\uff0c\u800c\u4e14\u8bbf\u95ee\u8bf7\u6c42\u4e5f\u4e0d\u5747\u5300\uff0c\u8fd9\u5c31\u5bfc\u81f4\u4e86\u9ad8\u5cf0\u671f\u521b\u5efa\u5927\u91cf\u6570\u636e\u5e93\u8fde\u63a5\u6c60\uff0c\u4f4e\u5cf0\u671f\u53c8\u88ab\u56de\u6536\u3002\u4f7f<code>com.mysql.jdbc.NonRegisteringDriver#connectionPhantomRefs<\/code>\u00a0\u4e2d\u7684\u5bf9\u8c61\u8d8a\u6765\u8d8a\u591a\uff0c\u800c\u4e14\u5927\u90e8\u5206\u8fdb\u5165\u8001\u5e74\u4ee3\uff0c\u9700\u8981fullGC\u6216\u8005G1 \u7684mixedGC\u624d\u80fd\u8fdb\u884c\u56de\u6536\u3002<\/p>\n<h2>4. \u89e3\u51b3\u65b9\u6848<\/h2>\n<h3>\u65b9\u68481\uff1a\u8c03\u6574JVM\u53c2\u6570<\/h3>\n<p>\u867d\u7136\u95ee\u9898\u7684\u6839\u6e90\u662fMySQL\u7684\u94fe\u63a5\u5931\u6548\uff0c\u9020\u6210\u865a\u5f15\u7528\u5728gc\u7684remark\u9636\u6bb5\u8017\u65f6\u8f83\u957f\u3002\u4f46\u662f\u6211\u4eec\u7684G1\u53c2\u6570\u914d\u7f6e\u4e5f\u5b58\u5728\u95ee\u9898\uff1a\u5176\u4e2d\u53c2\u65701\u7684\u8c03\u6574\u662f\u672c\u6b21\u51cf\u5c11GC\u65f6\u95f4\u7684\u5173\u952e\u3002<\/p>\n<h4>\u53c2\u65701\uff1aParallelRefProcEnabled \uff08\u5e76\u884c\u5f15\u7528\u5904\u7406\u5f00\u542f\uff09<\/h4>\n<p>\u7ecf\u8fc7\u6838\u67e5\u5e94\u7528\u786e\u8ba4\u4e3aG1GC \u53c2\u6570\u914d\u7f6e\u4e0d\u5f53\uff0c\u672a\u5f00\u542fParallelRefProcEnabled\uff08\u5e76\u884c\u5f15\u7528\u5904\u7406\uff09JDK8\u9700\u8981\u624b\u52a8\u5f00\u542f\uff0cJDK9+\u5df2\u9ed8\u8ba4\u5f00\u542f\u3002 \u5bfc\u81f4G1 Final Remark\u9636\u6bb5\u4f7f\u7528\u5355\u7ebf\u7a0b\u6807\u8bb0\uff08G1\u6df7\u5408GC\u7684\u65f6\u5019\uff0cSTW\u7ea6\u4e3a2~3\u79d2)\uff1b<\/p>\n<p><strong>\u89e3\u51b3\u65b9\u6848\uff1a<\/strong><\/p>\n<p>\u5f00\u542fParallelRefProcEnabled\uff08\u5e76\u884c\u5f15\u7528\u5904\u7406\uff09\u529f\u80fd\u540e\uff0cParallelGCThreads=8 \u542f\u75288\u7ebf\u7a0b\u6807\u8bb0\uff1b<\/p>\n<h4>\u53c2\u65702\uff1aParallelGCThreads \uff08\u5e76\u884c GC \u7ebf\u7a0b\u6570\uff09<\/h4>\n<p><code>ParallelGCThreads<\/code>\u53c2\u6570\u662f\u4e00\u4e2a\u7528\u4e8e\u6307\u5b9aG1\u5783\u573e\u56de\u6536\u5668\u5e76\u884c\u5783\u573e\u6536\u96c6\u7ebf\u7a0b\u6570\u7684\u53c2\u6570\u3002\u4e0e\u5176\u4ed6Java\u5783\u573e\u56de\u6536\u5668\u4e0d\u540c\uff0cG1\u5783\u573e\u56de\u6536\u5668\u53ef\u4ee5\u540c\u65f6\u6267\u884c\u591a\u4e2a\u5783\u573e\u56de\u6536\u7ebf\u7a0b\u6765\u52a0\u901f\u5783\u573e\u56de\u6536\u901f\u5ea6\u3002<\/p>\n<p>\u5728Java 8\u4e2d\uff0c\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0cG1\u5783\u573e\u56de\u6536\u5668\u7684<code>ParallelGCThreads<\/code>\u53c2\u6570\u8bbe\u7f6e\u4e3a\u4e0eCPU\u6838\u5fc3\u6570\u91cf\u76f8\u540c\u7684\u503c\uff0c\u6700\u5927\u4e3a8\u3002\u5982\u679c\u60a8\u7684\u673a\u5668\u6709\u66f4\u591a\u7684CPU\u6838\u5fc3\uff0c\u5219\u53ef\u4ee5\u901a\u8fc7\u624b\u52a8\u8c03\u6574\u8be5\u53c2\u6570\u6765\u63d0\u9ad8\u5e76\u884c\u5783\u573e\u56de\u6536\u7684\u6548\u7387\u3002\u4f8b\u5982\uff0c\u5982\u679c\u60a8\u7684\u673a\u5668\u67098\u4e2a\u6838\u5fc3\uff0c\u5219\u53ef\u4ee5\u5c06<code>ParallelGCThreads<\/code>\u8bbe\u7f6e\u4e3a8\u6216\u66f4\u9ad8\u7684\u503c\u3002<\/p>\n<p>\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u8fc7\u9ad8\u7684<code>ParallelGCThreads<\/code>\u503c\u53ef\u80fd\u4f1a\u5bfc\u81f4\u5904\u7406\u5668\u4e89\u7528\u548c\u4e0a\u4e0b\u6587\u5207\u6362\uff0c\u4ece\u800c\u5f71\u54cd\u5e94\u7528\u7a0b\u5e8f\u7684\u6027\u80fd\u3002\u56e0\u6b64\uff0c\u5728\u8fdb\u884c\u8c03\u6574\u65f6\uff0c\u5e94\u6839\u636e\u673a\u5668\u89c4\u683c\u548c\u5b9e\u9645\u8d1f\u8f7d\u8fdb\u884c\u6d4b\u8bd5\u548c\u4f18\u5316\uff0c\u4ee5\u627e\u5230\u6700\u4f73\u53c2\u6570\u914d\u7f6e\u3002\u5efa\u8bae\u4fdd\u6301\u9ed8\u8ba4\u503c\uff0c\u5e76\u5728\u5b9e\u6d4b\u7ed3\u679c\u53cd\u9988\u4e4b\u540e\u518d\u8fdb\u884c\u9002\u5f53\u7684\u8c03\u6574\u3002<\/p>\n<p>\u53e6\u5916\uff0c\u8fd8\u53ef\u4ee5\u4f7f\u7528<code>-XX:+UseDynamicNumberOfGCThreads<\/code>\u53c2\u6570\u8ba9G1\u81ea\u52a8\u9002\u914d\u5e76\u884c\u7ebf\u7a0b\u6570\u3002\u8fd9\u6837\uff0c\u7ebf\u7a0b\u6570\u91cf\u4f1a\u6839\u636e\u7cfb\u7edf\u8d1f\u8f7d\u81ea\u52a8\u589e\u51cf\uff0c\u4ece\u800c\u83b7\u5f97\u66f4\u597d\u7684\u6027\u80fd<\/p>\n<p><strong>\u89e3\u51b3\u65b9\u6848\uff1a<\/strong><\/p>\n<p>\u673a\u5668\u4e3a8\u6838\uff0c\u6700\u5f00\u59cb\u53ea\u914d\u7f6e\u4e866C\uff0c\u6545\u800c\u5c06\u5e76\u884cGC\u7ebf\u7a0b\u6570\u91cf\u589e\u52a0\u52308\uff0c\u6216\u8005\u4e0d\u4e0d\u914d\u7f6e\uff0c\u9ed8\u8ba4\u4e3a\u6838\u5fc3\u65708\uff1b<\/p>\n<h4>\u53c2\u65703\uff1aG1MixedGCLiveThresholdPercent \uff08G1\u6df7\u5408\u5783\u573e\u56de\u6536\u5668\u5b58\u6d3b\u9608\u503c\u767e\u5206\u6bd4\uff09<\/h4>\n<p><code>G1MixedGCLiveThresholdPercent<\/code>\u662f\u4e00\u4e2a\u7528\u4e8e\u63a7\u5236G1\u5783\u573e\u56de\u6536\u5668\u6df7\u5408\u5783\u573e\u56de\u6536\u7684\u53c2\u6570\uff0c\u5b83\u51b3\u5b9a\u6df7\u5408\u5783\u573e\u56de\u6536\u5668\u5728\u4f55\u65f6\u6267\u884c\u3002\u8fd9\u4e2a\u503c\u6307\u67d0\u4e00\u4e2a\u6807\u8bb0\u4e3aold region\u7684\u533a\u57df\u4e2d\u5b58\u6d3b\u5bf9\u8c61\u767e\u5206\u8fbe\u5230\u6b64\u9608\u503c\u540e\uff0c\u4f1a\u88abG1 mixed GC\u56de\u6536\u5904\u7406\uff1b<\/p>\n<p>\u5982\u679c\u5c06\u8be5\u503c\u8bbe\u7f6e\u5f97\u592a\u4f4e\uff0c\u5219\u53ef\u80fd\u5bfc\u81f4\u9891\u7e41\u7684\u6df7\u5408\u5783\u573e\u56de\u6536\uff0c\u4ece\u800c\u5f71\u54cd\u5e94\u7528\u7a0b\u5e8f\u7684\u6027\u80fd\uff1b\u5982\u679c\u5c06\u5176\u8bbe\u7f6e\u5f97\u592a\u9ad8\uff0c\u5219\u53ef\u80fd\u4f1a\u5bfc\u81f4\u8001\u5e74\u4ee3\u4e2d\u7684\u5783\u573e\u589e\u52a0\uff0c\u9020\u6210\u5806\u5185\u5b58\u5360\u7528\u8fc7\u9ad8\uff0c\u5355\u6b21STW\u5ef6\u957f\u3002<\/p>\n<p>\u9ed8\u8ba4\u503c\uff1a 85%;<\/p>\n<p><strong>\u89e3\u51b3\u65b9\u6848\uff1a<\/strong><\/p>\n<p>\u56e0\u4e3a\u524d\u671f\u8bbe\u7f6e\u4e3a80\uff0c \u672c\u6b21\u8c03\u6574\u4e3a60 \uff0c \u867d\u7136\u589e\u52a0\u6df7\u5408GC\u89e6\u53d1\u7684\u9891\u7387\uff0c\u4f46\u662f\u56e0\u4e3a\u6b64\u65f6\u5bf9\u8c61\u66f4\u5c11\uff0c\u9700\u8981\u6d88\u8017\u7684\u65f6\u95f4\u4e5f\u53d8\u77ed\uff1b<\/p>\n<h4>\u53c2\u65704\uff1a MaxTenuringThreshold \uff08\u5bf9\u8c61\u664b\u5347\u5230\u8001\u5e74\u4ee3\u7684\u6700\u5927\u5e74\u9f84\uff09<\/h4>\n<p><code>MaxTenuringThreshold<\/code>\u662f\u4e00\u4e2a\u7528\u4e8e\u63a7\u5236\u5bf9\u8c61\u5728Survivor\u533a\u57df\u4e2d\u5b58\u6d3b\u7684\u65f6\u95f4\u9608\u503c\u7684\u53c2\u6570\uff0c\u5b83\u6307\u5b9a\u4e86\u5bf9\u8c61\u5728\u7ecf\u8fc7\u591a\u5c11\u6b21Minor GC\u540e\u53ef\u4ee5\u664b\u5347\u5230\u8001\u5e74\u4ee3\u3002\u5177\u4f53\u6765\u8bf4\uff0c\u5982\u679c\u67d0\u4e2a\u5bf9\u8c61\u5728Survivor\u533a\u57df\u4e2d\u5b58\u6d3b\u4e86\u8db3\u591f\u957f\u7684\u65f6\u95f4\uff08\u5373\u7ecf\u8fc7\u8db3\u591f\u591a\u6b21\u7684Minor GC\uff09\uff0c\u5219\u4f1a\u88ab\u79fb\u52a8\u5230\u8001\u5e74\u4ee3\u4e2d\u3002<\/p>\n<p>\u5728Java 8\u4e2d\uff0c\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0c<code>MaxTenuringThreshold<\/code>\u53c2\u6570\u8bbe\u7f6e\u4e3a15\uff0c\u5373\u5bf9\u8c61\u5fc5\u987b\u5728Survivor\u533a\u57df\u4e2d\u5b58\u6d3b15\u6b21Minor GC\u624d\u80fd\u664b\u5347\u5230\u8001\u5e74\u4ee3\u3002\u5982\u679c\u5c06\u5176\u8bbe\u7f6e\u4e3a0\uff0c\u5219\u8868\u793a\u6240\u6709\u7684\u5bf9\u8c61\u90fd\u53ef\u4ee5\u5728\u7b2c\u4e00\u6b21Minor GC\u65f6\u664b\u5347\u5230\u8001\u5e74\u4ee3\uff1b\u5982\u679c\u5c06\u5176\u8bbe\u7f6e\u4e3a\u8f83\u5927\u7684\u503c\uff0c\u5219\u8868\u793a\u53ea\u6709\u5b58\u6d3b\u65f6\u95f4\u6bd4\u8f83\u957f\u7684\u5bf9\u8c61\u624d\u80fd\u664b\u5347\u5230\u8001\u5e74\u4ee3\u3002<\/p>\n<p>\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u5982\u679c\u5c06<code>MaxTenuringThreshold<\/code>\u53c2\u6570\u8bbe\u7f6e\u5f97\u8fc7\u5c0f\uff0c\u5219\u53ef\u80fd\u5bfc\u81f4\u9891\u7e41\u7684\u664b\u5347\u548c\u56de\u6536\u64cd\u4f5c\uff0c\u4ece\u800c\u5f71\u54cd\u5e94\u7528\u7a0b\u5e8f\u7684\u6027\u80fd\uff1b\u5982\u679c\u5c06\u5176\u8bbe\u7f6e\u5f97\u8fc7\u5927\uff0c\u5219\u53ef\u80fd\u4f1a\u5bfc\u81f4Survivor\u533a\u57df\u4e2d\u7684\u7a7a\u95f4\u4e0d\u8db3\uff0c\u4ece\u800c\u5f3a\u5236\u8fdb\u884cFull GC\u64cd\u4f5c\uff0c\u540c\u6837\u4e5f\u4f1a\u5f71\u54cd\u5e94\u7528\u7a0b\u5e8f\u7684\u6027\u80fd\u3002<\/p>\n<p>\u5efa\u8bae\u5728\u5b9e\u9645\u5e94\u7528\u7a0b\u5e8f\u573a\u666f\u4e2d\u8fdb\u884c\u6d4b\u8bd5\u548c\u4f18\u5316\uff0c\u4ee5\u627e\u5230\u6700\u4f73\u7684<code>MaxTenuringThreshold<\/code>\u503c\u3002\u901a\u5e38\uff0c\u8be5\u503c\u5e94\u8be5\u8bbe\u7f6e\u57288-15\u4e4b\u95f4\uff0c\u5e76\u4e14\u5e94\u6839\u636e\u5e94\u7528\u7a0b\u5e8f\u7684\u5185\u5b58\u4f7f\u7528\u60c5\u51b5\u548cGC\u65e5\u5fd7\u8fdb\u884c\u8c03\u6574\u3002<\/p>\n<p><strong>\u89e3\u51b3\u65b9\u6848\uff1a<\/strong><\/p>\n<p>\u56e0\u4e3a\u524d\u671f\u8bbe\u7f6e\u4e3a5\uff0c \u672c\u6b21\u8c03\u6574\u4e3a15 \uff0c\u6216\u8005\u4e0d\u9700\u8981\u914d\u7f6e\uff0c\u9ed8\u8ba4\u4e3a15\uff1b<\/p>\n<h4>\u8c03\u6574\u540e\u7684JVM\u53c2\u6570<\/h4>\n<pre><code>-Xms9984m  -Xmx9984m  -XX:MaxMetaspaceSize=512m -XX:MetaspaceSize=512m  -XX:MaxDirectMemorySize=512m  -XX:ParallelGCThreads=8  -XX:CICompilerCount=4  -XX:ConcGCThreads=4 -server -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:SurvivorRatio=10 -XX:InitiatingHeapOccupancyPercent=45 -XX:G1ReservePercent=20 -XX:G1MixedGCLiveThresholdPercent=60 -XX:MaxGCPauseMillis=100 -XX:+ExplicitGCInvokesConcurrent -XX:+ParallelRefProcEnabled -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintReferenceGC  -XX:+PrintHeapAtGC -Xloggc:\/export\/Logs\/app\/tomcat7-gc.log <\/code><\/pre>\n<h3>\u65b9\u68482\uff1a \u4f18\u5316MySQL\u7684\u865a\u5f15\u7528\u95ee\u9898<\/h3>\n<h4>\u8c03\u6574\u8fde\u63a5\u6c60\u53c2\u6570<\/h4>\n<p>\u5728\u8bf8\u591a\u8fde\u63a5\u6c60\u4e2d\uff0c\u53d1\u73b0\u4e00\u4e2a\u53c2\u6570\u914d\u7f6e\u9519\u8bef\uff0c\u6709\u4e00\u4e2a\u6570\u636e\u5e93\u7684<code>db.minEvictableIdleTimeMillis<\/code>=180000\uff083\u5206\u949f\uff09\uff0c\u9002\u5f53\u8c03\u5927\u8fde\u63a5\u7684\u95f2\u7f6e\u65f6\u95f4\u523030Min\uff1b<\/p>\n<p>\u5c06DBCP\u8fde\u63a5\u6c60\u53c2\u6570minIdle\u8c03\u5c0f\uff0c\u51cf\u5c11\u95f2\u7f6e\u7ebf\u7a0b\u7684\u6570\u91cf\uff08\u5728\u6574\u4e2a\u8fde\u63a5\u90fd\u4e0d\u6d3b\u8dc3\u7684\u60c5\u51b5\u4e0b\uff09\uff0c\u4e5f\u53ef\u4ee5\u8d77\u5230\u4e00\u5b9a\u4f5c\u7528\uff1b<\/p>\n<p>\u4f46\u662f\u8fd9\u4e2a\u65b9\u5f0f\uff0c\u6cbb\u6807\u4e0d\u6cbb\u672c\uff0c \u56e0\u4e3a\u865a\u5f15\u7528\u8fd8\u5728\u4e00\u76f4\u4ea7\u751f\u3002<\/p>\n<h4>\u4f18\u5316MySQL driver\u865a\u5f15\u7528<\/h4>\n<h5>A. \u53cd\u5c04\u66b4\u529b\u6e05\u7406<\/h5>\n<p>\u865a\u5f15\u7528\u5f80\u5f80\u505a\u4e3a\u4e00\u79cd\u515c\u5e95\u7b56\u7565\uff0c\u907f\u514d\u7528\u6237\u5fd8\u8bb0\u91ca\u653e\u8d44\u6e90\uff0c\u5f15\u53d1\u5185\u5b58\u6cc4\u9732\uff08\u5728\u672a\u4f7f\u7528\u8fde\u63a5\u6c60\u7684\u5982java\u521d\u5b66\u8005\u624b\u64b8\u7684\u6570\u636e\u5e93\u94fe\u63a5\u7ba1\u7406\u4ee3\u7801\u5f80\u5f80\u662f\u6709\u7528\u7684\uff09\u3002\u6211\u4eec\u4f7f\u7528DBCP\u6216\u5176\u5b83\u6c60\u5316\u6280\u672f\u5df2\u7ecf\u4f1a\u4e25\u8c28\u5904\u7406\u8d44\u6e90\u7684\u91ca\u653e\uff0c\u53ef\u4ee5\u4e0d\u91c7\u7528\u515c\u5e95\u7b56\u7565\uff0c\u76f4\u63a5\u5220\u9664\u4e2d connectionPhantomRefs \u4e2d\u7684\u865a\u5f15\u7528\uff0c\u4f7f\u5bf9\u8c61\u4e0d\u53ef\u8fbe\uff0c\u5728 GC \u65f6\u76f4\u63a5\u56de\u6536\uff0c\u4ece\u800c\u51cf\u5c11 PhantomReference \u7684\u5904\u7406\u65f6\u95f4\u3002<\/p>\n<pre><code>\/\/ \u6bcf\u4e24\u5c0f\u65f6\u6e05\u7406 connectionPhantomRefs\uff0c\u51cf\u5c11\u5bf9 mixed GC \u7684\u5f71\u54cd\nSCHEDULED_EXECUTOR.scheduleAtFixedRate(() -&gt; {\n  try {\n    Field connectionPhantomRefs = NonRegisteringDriver.class.getDeclaredField(&quot;connectionPhantomRefs&quot;);\n    connectionPhantomRefs.setAccessible(true);\n    Map map = (Map) connectionPhantomRefs.get(NonRegisteringDriver.class);\n    if (map.size() &gt; 50) {\n      map.clear();\n    }\n  } catch (Exception e) {\n    log.error(&quot;connectionPhantomRefs clear error!&quot;, e);\n  }\n}, 2, 2, TimeUnit.HOURS);<\/code><\/pre>\n<p>\u4ee5\u4e0a\u4ee3\u7801\u901a\u8fc7\u53cd\u5c04\u5b9a\u65f6\u6e05\u7406\u6389NonRegisteringDriver\u9759\u6001\u53d8\u91cfconnectionPhantomRefs\uff0c\u5373\u4fe1\u4efbDBCP\u5728\u94fe\u63a5\u56de\u6536\u7684\u65f6\u5019\uff0c\u4f1a\u81ea\u52a8\u4e25\u8c28\u5904\u7406\u8d44\u6e90\u91ca\u653e\u3002MySQL driver\u81ea\u5e26\u7684\u5b89\u5168\u9632\u62a4\u5168\u90e8\u5b9a\u65f6\u6e05\u7a7a\uff0c\u76f8\u5f53\u4e8e\u7981\u7528\u6b64\u529f\u80fd\u3002<\/p>\n<p><strong>\u7279\u522b\u8bf4\u660e\uff1a<\/strong> \u00a0A\u65b9\u6848\u65e0\u5b89\u5168\u6027\u95ee\u9898\uff0c\u53ef\u653e\u5fc3\u91c7\u7eb3\uff1b<\/p>\n<h5>B. \u5347\u7ea7MySQL jdbc driver\u52308.0.22+\uff0c\u5f00\u542fdisableAbandonedConnectionCleanup<\/h5>\n<p>Oracle\u5e94\u8be5\u662f\u63a5\u6536\u4e86\u5927\u91cf\u5f00\u53d1\u4eba\u5458\u7684\u53cd\u9988\uff0c\u610f\u8bc6\u5230\u4e86\u6b64\u529f\u80fd\u53ef\u80fd\u9020\u6210GC\u4e25\u91cd\u8fc7\u957f\u7684\u95ee\u9898\uff0c\u5728\u9ad8\u7248\u672c\u4e2d\u5df2\u7ecf\u53ef\u4ee5\u901a\u8fc7\u914d\u7f6e\u9009\u62e9\u6027\u5173\u95ed\u6b64\u975e\u5fc5\u8981\u62d6\u5c3e\u529f\u80fd\u3002 mysql-connector-java \u7248\u672c\uff088.0.22+\uff09\u7684\u4ee3\u7801\u5bf9\u6570\u636e\u5e93\u8fde\u63a5\u7684\u865a\u5f15\u7528\u6709\u65b0\u7684\u5904\u7406\u65b9\u5f0f\uff0c\u5176\u589e\u52a0\u4e86\u5f00\u5173\uff0c\u53ef\u4ee5\u624b\u52a8\u5173\u95ed\u6b64\u529f\u80fd\u3002<\/p>\n<p>\u5176\u7248\u672c8.0.22\u4ecb\u7ecd\u589e\u52a0\u6b64\u53c2\u6570\u5373\u662f\u4e3a\u4e86\u89e3\u51b3JVM \u865a\u5f15\u7528\u76f8\u5173\u95ee\u9898\uff0c\u4f46\u662f\u9ed8\u8ba4\u662f\u672a\u542f\u7528\uff0c\u9700\u8981\u624b\u52a8\u5f00\u542f\uff1a<\/p>\n<pre><code>https:\/\/dev.mysql.com\/doc\/relnotes\/connector-j\/8.0\/en\/news-8-0-22.html\n\nWhen using Connector\/J, the AbandonedConnectionCleanupThread thread can now be disabled completely by setting the new system property com.mysql.cj.disableAbandonedConnectionCleanup to true when configuring the JVM. The feature is for well-behaving applications that always close all connections they create. Thanks to Andrey Turbanov for contributing to the new feature. (Bug #30304764, Bug #96870)<\/code><\/pre>\n<p>\u200b \u6709\u4e86\u8fd9\u4e2a\u914d\u7f6e\uff0c\u5c31\u53ef\u4ee5\u5728\u542f\u52a8\u53c2\u6570\u4e0a\u8bbe\u7f6e\u5c5e\u6027\uff1a<\/p>\n<pre><code>java -jar app.jar -Dcom.mysql.cj.disableAbandonedConnectionCleanup=true<\/code><\/pre>\n<p>\u200b \u6216\u8005\u5728\u4ee3\u7801\u91cc\u8bbe\u7f6e\u5c5e\u6027\uff1a<\/p>\n<pre><code>System.setProperty(PropertyDefinitions.SYSP_disableAbandonedConnectionCleanup,&quot;true&quot;);<\/code><\/pre>\n<p>\u5f53 com.mysql.cj.disableAbandonedConnectionCleanup=true \u65f6\uff0c\u751f\u6210\u6570\u636e\u5e93\u8fde\u63a5\u65f6\u5c31\u4e0d\u4f1a\u751f\u6210\u865a\u5f15\u7528\uff0c\u5bf9 GC \u5c31\u6ca1\u6709\u4efb\u4f55\u5f71\u54cd\u4e86\u3002<\/p>\n<p>\u662f\u5426\u5347\u7ea7MySQL\u7684\u9a71\u52a8\u7248\u672c\uff0c\u6839\u636e\u5b9e\u9645\u60c5\u51b5\u53d6\u820d\uff0c\u4ee5\u4e0aA\/B\u65b9\u6848\u90fd\u80fd\u89e3\u51b3\u8be5\u95ee\u9898\u3002<\/p>\n<h2>\u603b\u7ed3<\/h2>\n<h3>G1\u53c2\u6570\u8c03\u4f18\u603b\u7ed3<\/h3>\n<ol>\n<li>ParallelGCThreads \u4e3b\u8981\u4e3a\u5e76\u53d1\u6807\u8bb0\u76f8\u5173\u7ebf\u7a0b\uff0c\u5176\u672c\u8eab\u5904\u7406\u65f6\u5019\u4e5f\u4f1aSTW\uff0c \u6700\u597d\u5168\u90e8\u5360\u7528CPU\u5185\u6838\uff0c\u5982\u673a\u5668\u4e3a8\u6838\uff0c\u5219\u8be5\u503c\u6700\u597d\u8bbe\u7f6e\u4e3a8\uff1b<\/li>\n<li>ConcGCThreads \u4e3a\u5e76\u53d1\u6807\u8bb0\u7ebf\u7a0b\u6570\u91cf\uff0c\u5176\u6807\u8bb0\u7684\u65f6\u5019\uff0c\u4e1a\u52a1\u7ebf\u7a0b\u53ef\u4ee5\u4e0dSTW\uff0c \u53ef\u4ee5\u4f7f\u7528\u90e8\u5206\u6838\u5fc3\uff0c\u5269\u4f59\u90e8\u5206\u6838\u5fc3\u7528\u4e8e\u8dd1\u4e1a\u52a1\u7ebf\u7a0b\uff1b\u6211\u4eec\u8fd9\u91cc\u914d\u7f6e\u4e3aCPU\u6838\u5fc3\u6570\u91cf\u7684\u4e00\u534a4\uff1b<\/li>\n<li>MaxGCPauseMillis \u53ea\u662f\u4e00\u4e2a\u671f\u671b\u503c\uff08GC\u4f1a\u5c3d\u53ef\u80fd\u4fdd\u8bc1\uff09\uff0c\u5e76\u4e0d\u80fd\u4e25\u683c\u9075\u5b88\uff0c\u5c24\u5176\u662f\u5728\u6807\u8bb0\u9636\u6bb5\uff0c\u4f1a\u53d7\u5230\u5806\u5185\u5b58\u5bf9\u8c61\u6570\u91cf\u7684\u5f71\u54cd\uff0c\u6545\u800c\u4e0d\u80fd\u592a\u8fc7\u4f9d\u8d56\u6b64\u503c\u89c9\u5f97STW\u7684\u5b9e\u9645\u65f6\u95f4\uff1b\u5982\u6211\u65b9\u914d\u7f6e\u7684100ms\uff0c \u5b9e\u9645\u51fa\u73b03~4\u79d2\u7684\u673a\u4f1a\u4e5f\u6bd4\u8f83\u591a\uff1b<\/li>\n<li>ParallelRefProcEnabled \u5982\u679c\u4f60\u641c\u7d22\u7684\u5404\u79cd\u8d44\u6599\u63d0\u9192\u4f60\u8fd9\u4e2a\u5f00\u5173\u662f\u9ed8\u8ba4\u5f00\u542f\u7684\uff0c\u90a3\u4f60\u8981\u7279\u522b\u6ce8\u610f\u4e86\uff1b JDK8\u7248\u672c\u6b64\u529f\u80fd\u662f\u9ed8\u8ba4\u5173\u95ed\u7684\uff0c\u5728JDK9+\u4e4b\u540e\u624d\u662f\u9ed8\u8ba4\u5f00\u542f\u3002\u6545\u800cJDK8\u9700\u8981\u624b\u52a8\u5f00\u542f\uff0c\u4fdd\u9669\u8d77\u89c1\uff0c\u65e0\u8bba\u4ec0\u4e48\u7248\u672c\u90fd\u914d\u7f6e\u8be5\u503c\uff1b<\/li>\n<li>G1\u5783\u573e\u56de\u6536\u5668\u57fa\u672c\u4e0a\u4e0d\u4f1a\u51fa\u73b0fullGC, \u5728youngGC \u548c mixedGC\uff08mixedGC\u9891\u6b21\u4e5f\u4e0d\u9ad8\uff09\u5c31\u5b8c\u6210\u4e86\u5783\u573e\u56de\u6536\u3002\u5982\u679c\u51fa\u73b0\u4e86fullGC\uff0c \u53cd\u800c\u5e94\u8be5\u6392\u67e5\u662f\u5426\u6709\u5f02\u5e38\u3002<\/li>\n<li>\u672c\u6587\u672a\u5bf9G1\u5783\u573e\u56de\u6536\u5668\u4e4b\u8fc7\u7a0b\u53ca\u539f\u7406\u8fdb\u884c\u8be6\u7ec6\u5206\u6790\uff0c\u8bf7\u53c2\u8003\u5176\u5b83\u6587\u7ae0\u8fdb\u884c\u7406\u89e3\uff1b<\/li>\n<\/ol>\n<p>\u9644\u5f55\uff1a<a href=\"https:\/\/link.segmentfault.com\/?enc=aAMPqCpiuSmbI%2ByBmuIEsw%3D%3D.UXptiaRDwiu5IA72WmZyZxpLpKL2l6zp297UidtjlTaJORkBHHA5pk3gF2Bk6lUGqlftVgIlfZH5lSs%2FSVwMLGz48zKFTiTqnz9q0lhGw1s1kvHNIgU64EaUCXEZ1r9F\" rel=\"nofollow\">Oracle\u5b98\u65b9JDK8 G1\u53c2\u6570\u8c03\u4f18\u5b98\u65b9\u6587\u6863<\/a><\/p>\n<h3>MySQL\u865a\u5f15\u7528\u95ee\u9898\u603b\u7ed3<\/h3>\n<ol>\n<li>MySQL \u94fe\u63a5\u9a71\u52a8\u5982\u679c\u57288.0.22\u7248\u672c\u4ee5\u4e0b\uff0c\u53ea\u80fd\u901a\u8fc7\u53cd\u5c04\u4e3b\u52a8\u6e05\u7406\u6b64\u975e\u5fc5\u8981\u62d6\u5c3e\u529f\u80fd\uff08\u4e00\u822c\u6210\u719f\u7684\u6570\u636e\u5e93\u8fde\u63a5\u6c60\u529f\u80fd\u90fd\u80fd\u5b89\u5168\u91ca\u653e\u94fe\u63a5\u76f8\u5173\u8d44\u6e90\uff09\u3002<\/li>\n<li>MySQL\u9a71\u52a88.0.22+\u7248\u672c\uff0c \u53ef\u4ee5\u901a\u8fc7\u914d\u7f6e\u624b\u52a8\u5173\u95ed\u6b64\u529f\u80fd\uff1b<\/li>\n<\/ol>\n<h2>\u7ed3\u679c\u8bf4\u660e<\/h2>\n<p>\u7ecf\u8fc7\u4ee5\u4e0a\u8c03\u6574\u540e\uff08MySQL\u7684\u865a\u5f15\u7528\u95ee\u9898\u4e00\u5e76\u89e3\u51b3\u540e\uff09\uff0cgc\u65f6\u95f4\u80fd\u8f83\u597d\u7684\u63a7\u5236\u5728100ms\u4ee5\u5185\uff0c\u5e73\u5747\u8017\u65f626ms\u3002 mixed gc\u9891\u7387\u5927\u5e45\u5ea6\u51cf\u5c11\uff0c \u4e3b\u8981\u4e3ayoungGC\u3002<\/p>\n<h2>\u53c2\u8003\u8d44\u6599<\/h2>\n<p><a href=\"https:\/\/link.segmentfault.com\/?enc=O%2B%2BqIxVH1RKcQ32XY4IidQ%3D%3D.kDnoi9MiAyM%2B1DE7VSRa%2F9VSizCPqeedvYtVDgsF4JNxSPrSCE3zKUFz8N9RKMmXPPepj5NEq95O7FqKUmTh6g%3D%3D\" rel=\"nofollow\">\u7ebf\u4e0a\u95ee\u9898\u5206\u6790\u7cfb\u5217\uff1a\u6570\u636e\u5e93\u8fde\u63a5\u6c60\u5185\u5b58\u6cc4\u6f0f\u95ee\u9898\u7684\u5206\u6790\u548c\u89e3\u51b3\u65b9\u6848<\/a><\/p>\n<p><a href=\"https:\/\/link.segmentfault.com\/?enc=n3EOVnveuOOIRwRFidtiGA%3D%3D.qHagWYOKB2I9ifHe78P1cbmD9z7KKTYk%2ByEHuzMFE9xZwOWCboJHpL%2BvC%2BivbF2ADMor28Wd%2FKNoh%2FiT1pY00Q%3D%3D\" rel=\"nofollow\">com.mysql.jdbc.NonRegisteringDriver \u5185\u5b58\u6cc4\u6f0f<\/a><\/p>\n<p><a href=\"https:\/\/link.segmentfault.com\/?enc=o3rbNiycKh%2B6pGkTiNjRoQ%3D%3D.Bwg6CriPKmf45nqnkUUu4sgsO43E9N%2BSCL%2Fuxv3%2FdKDGRM%2FUvrcozf8u0nGmNfcjk9TLTEAUdURjySHQ3YPZPA%3D%3D\" rel=\"nofollow\">\u795e\u706f-\u7ebf\u4e0a\u95ee\u9898\u5904\u7406\u6848\u4f8b1\uff1a\u51fa\u4e4e\u610f\u6599\u7684\u6570\u636e\u5e93\u8fde\u63a5\u6c60<\/a><\/p>\n<p><a href=\"https:\/\/link.segmentfault.com\/?enc=pnrgCkskcHn2yVBNLji4lg%3D%3D.i9JZHhqpmHyi%2BCfzpeCB8iyn5eoGw%2FferlWQrwdCR3LF80G2np037DuTlMhaSkry\" rel=\"nofollow\">G1\u6536\u96c6\u5668\u8be6\u89e3\u53ca\u8c03\u4f18<\/a><\/p>\n<p><a href=\"https:\/\/link.segmentfault.com\/?enc=CN7dcW6O8YOjfZ0hOWbMqQ%3D%3D.JYXb%2FjEniIJTZNnVwIIoplSKibaL49kzwew%2F6FzbK0uLgDdAz96QmNoEJMPv6DSs%2BfAQfi77o%2FUFfIcy6UOWfQ%3D%3D\" rel=\"nofollow\">infoq-Tips for Tuning the Garbage First Garbage Collector<\/a><\/p>\n<p><a href=\"https:\/\/link.segmentfault.com\/?enc=Od44eFq3wGzPHfal1X0esw%3D%3D.TEzsonCR52agYQzVr9AwmXkwe6SXcIXRF83BGzokDZe5Tl4Ni3dk2X978vGA1dMbPbrAoFQOcPrfY8B9qGGfpw%3D%3D\" rel=\"nofollow\">Java Garbage Collection handbook<\/a><\/p>\n<p><a href=\"https:\/\/link.segmentfault.com\/?enc=1yW9sCUgAVIoYGrXLbFZYg%3D%3D.EUOQopPGs79%2FxKXpIMQXFaQ%2FbsiMtbPidGvb4o7Qf57qudsFyWAsbltc8z4uV57g\" rel=\"nofollow\">PPPHUANG-JVM \u4f18\u5316\u8e29\u5751\u8bb0<\/a><\/p>\n<p><a href=\"https:\/\/link.segmentfault.com\/?enc=TSEhTEGhljEJ%2B6R00DM7Rg%3D%3D.2KUGC%2Fik7tnsbS1f6X3Socf6hABWnOdtoC76UkNRR5QWJCj5IJSWKPOpgA0fMVZL\" rel=\"nofollow\">PPPHUANG- MySQL \u9a71\u52a8\u4e2d\u865a\u5f15\u7528 GC \u8017\u65f6\u4f18\u5316\u4e0e\u6e90\u7801\u5206\u6790<\/a><\/p>\n<blockquote>\n<p>\u4f5c\u8005\uff1a\u4eac\u4e1c\u96f6\u552e \u5f20\u4e16\u5f6c<\/p>\n<p>\u6765\u6e90\uff1a\u4eac\u4e1c\u4e91\u5f00\u53d1\u8005\u793e\u533a<\/p>\n<\/blockquote>\n<p><a href=\"https:\/\/segmentfault.com\/a\/1190000043943979\">https:\/\/segmentfault.com\/a\/1190000043943979<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>1. \u80cc\u666f \u6211\u65b9\u6709\u4e00\u5e94\u7528\uff0c\u5076\u5c14\u4f1a\u51fa\u73b0GC\u65f6\u95f4\u8fc7\u957f\uff08\u95f4\u9694\u7ea64\u5c0f\u65f6\uff09\uff0c\u5bfc\u81f4\u6027\u80fd\u6ce2\u52a8\u7684\u95ee\u9898(\u63a5\u53e3\u6700\u957f\u9700\u8981\u8017\u65f63\u79d2\u4ee5\u4e0a [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-10008008","post","type-post","status-publish","format-standard","hentry","category-share"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10008008","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10008008"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10008008\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10008008"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10008008"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10008008"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}