{"id":10006785,"date":"2022-11-01T19:07:09","date_gmt":"2022-11-01T11:07:09","guid":{"rendered":"https:\/\/ityet.com\/?p=10006785"},"modified":"2022-11-01T19:07:09","modified_gmt":"2022-11-01T11:07:09","slug":"g1%e5%9e%83%e5%9c%be%e5%9b%9e%e6%94%b6%e5%99%a8%e6%95%99%e7%a8%8b","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10006785","title":{"rendered":"G1\u5783\u573e\u56de\u6536\u5668\u6559\u7a0b"},"content":{"rendered":"<h2>1 G1 \u5783\u573e\u56de\u6536\u5668<\/h2>\n<p>garbage-first (G1)\u6536\u96c6\u5668\u662f\u4e00\u4e2a\u670d\u52a1\u5668\u98ce\u683c\u7684\u5783\u573e\u6536\u96c6\u5668\uff0c\u9488\u5bf9\u5177\u6709\u5927\u5185\u5b58\u7684\u591a\u5904\u7406\u5668\u673a\u5668\u3002\u5b83\u5728\u540c\u65f6\u5b9e\u73b0\u9ad8\u541e\u5410\u91cf\u7684\u60c5\u51b5\u4e0b\uff0c\u4ee5\u5f88\u9ad8\u7684\u6982\u7387\u6ee1\u8db3\u5783\u573e\u6536\u96c6(GC)\u6682\u505c\uff08STW:stop the word\uff09\u65f6\u95f4\u76ee\u6807\u3002G1\u5783\u573e\u6536\u96c6\u5668\u5728Oracle JDK 7 update 4\u548c\u66f4\u9ad8\u7248\u672c\u4e2d\u5f97\u5230\u4e86\u5b8c\u5168\u652f\u6301\u3002G1\u6536\u96c6\u5668\u4e13\u4e3a\u4ee5\u4e0b\u5e94\u7528\u7a0b\u5e8f\u8bbe\u8ba1:<\/p>\n<ul>\n<li>\u53ef\u4ee5\u5411 CMS \u5783\u573e\u56de\u6536\u5668\u4e00\u6837\u548c\u7528\u6237\u7ebf\u7a0b\u5e76\u884c\u3002<\/li>\n<li>\u4e0d\u4f1a\u6709\u957f\u65f6\u95f4\u7684 GC \u505c\u987f\uff0c\u4e14\u7a7a\u95f2\u7a7a\u95f4\u66f4\u7d27\u51d1\u3002<\/li>\n<li>\u9700\u8981\u66f4\u591a\u53ef\u9884\u6d4b\u7684GC\u6682\u505c\u65f6\u95f4\u3002<\/li>\n<li>\u4e0d\u5e0c\u671b\u727a\u7272\u5927\u91cf\u541e\u5410\u91cf<\/li>\n<li>\u4e0d\u9700\u8981\u4e00\u4e2a\u5f88\u5927\u7684 java \u5806<\/li>\n<\/ul>\n<p>G1 \u5783\u573e\u56de\u6536\u5668\u662f\u6253\u7b97\u4f5c\u4e3a CMS \u5783\u573e\u56de\u6536\u5668\u7684\u66ff\u4ee3\u54c1\u7684\u3002\u5bf9\u6bd4 G1 \u548c CMS\uff0c\u6709\u4e9b\u5dee\u5f02\u4f7f\u5f97 G1 \u662f\u4e00\u4e2a\u66f4\u597d\u7684\u9009\u62e9\u3002<\/p>\n<p>\u7b2c\u4e00\u4e2a\u533a\u522b\u662f\uff0cG1 \u662f\u4e00\u4e2a\u538b\u7f29\u56de\u6536\u5668\u3002G1 \u8fdb\u884c\u4e86\u5145\u5206\u7684\u538b\u7f29\uff0c\u4ee5\u907f\u514d\u4f7f\u7528\u7ec6\u7c92\u5ea6\u7684\u81ea\u7531\u5217\u8868\u6765\u5206\u914d\u7a7a\u95f4\uff0c\u800c\u662f\u4f7f\u7528\u533a\u57df\uff08region\uff09\u3002\u8fd9\u5728\u5f88\u5927\u7a0b\u5ea6\u4e0a\u7b80\u5316\u4e86\u56de\u6536\u5668\u7684\u90e8\u5206\uff0c\u5e76\u4e14\u57fa\u672c\u4e0a\u6d88\u9664\u4e86 CMS \u7684\u788e\u7247\u95ee\u9898\u3002<\/p>\n<p>\u7b2c\u4e8c\u4e2a\u533a\u522b\u662f\uff0cG1 \u63d0\u4f9b\u4e86\u6bd4 CMS \u56de\u6536\u5668\u66f4\u53ef\u9760\u9884\u6d4b\u505c\u987f\u65f6\u95f4\uff0c\u8fd9\u8ba9\u7528\u6237\u53ef\u4ee5\u6307\u5b9a\u9700\u8981\u7684\u505c\u987f\u65f6\u95f4\u3002<\/p>\n<h3>1.1 G1\u64cd\u4f5c\u6982\u8ff0<\/h3>\n<p>\u8001\u7684\u5783\u573e\u56de\u6536\u5668\uff08\u5982\uff1aserial\u3001paralle\u3001CMS\uff09\u90fd\u662f\u628a\u5185\u5b58\u5206\u4e3a\u4e09\u4e2a\u533a\u57df\uff1a\u5e74\u8f7b\u4ee3young\uff08\u5e74\u8f7b\u4ee3\u53c8\u5206\u4e3aeden\u3001S1\u3001S2\u4e09\u4e2a\u533a\u57df\uff09\uff0c\u8001\u5e74\u4ee3 old gerneration\uff0c\u6c38\u4e45\u4ee3 permanent\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722747\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>G1 \u91c7\u7528\u4e00\u79cd\u4e0d\u540c\u7684\u65b9\u6cd5\u3002<\/p>\n<p>G1 \u4e2d\u7684\u5806\u88ab\u5206\u4e3a\u4e00\u7cfb\u5217\u76f8\u540c\u5927\u5c0f\u7684\u5806\u533a\u57df\uff08region\uff0c\u4e5f\u6709\u4eba\u53eb\u5757\uff09\uff0c\u6bcf\u4e2a\u533a\u57df\u90fd\u662f\u8fde\u7eed\u7684\u865a\u62df\u5185\u5b58\u3002\u8fd9\u4e00\u7cfb\u5217\u7684\u5806\u533a\u57df\uff0c\u548c\u8001\u7684\u5783\u573e\u56de\u6536\u5668\u4e00\u6837\uff0c\u88ab\u8bbe\u5b9a\u4e3a\u4e09\u79cd\u89d2\u8272\uff08eden\u3001survivor\u3001old\uff09\uff0c\u4f46\u662f\u4ed6\u4eec\u7684\u5927\u5c0f\u4e0d\u56fa\u5b9a\uff0c\u8fd9\u7ed9\u5185\u5b58\u4f7f\u7528\u63d0\u4f9b\u4e86\u66f4\u5927\u7684\u5f39\u6027\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722748\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u5f53\u6267\u884c\u5783\u573e\u6536\u96c6\u7684\u65f6\u5019\uff0cG1 \u7684\u64cd\u4f5c\u65b9\u5f0f\u548c CMS \u7c7b\u4f3c\u3002G1 \u6267\u884c\u4e00\u4e2a\u5168\u5c40\u7684<strong>\u5e76\u53d1\u6807\u8bb0<\/strong>\u9636\u6bb5\uff0c\u6765\u786e\u5b9a\u5806\u4e2d\u5b58\u6d3b\u7684\u5bf9\u8c61\u3002\u6807\u8bb0\u9636\u6bb5\u7ed3\u675f\u4e4b\u540e\uff0cG1 \u77e5\u9053\u54ea\u4e2a\u533a\u57df\u5927\u90e8\u5206\u662f\u7a7a\u7684\uff08\u6211\u7406\u89e3\u662f\u5783\u573e\u6bd4\u8f83\u591a\u7684\u533a\u57df\uff09\u3002G1 \u4f1a\u4f18\u5148\u56de\u6536\u8fd9\u4e9b\u533a\u57df\uff0c\u8fd9\u6837\u5c31\u80fd\u591f\u91ca\u653e\u66f4\u591a\u7684\u7a7a\u95f2\u7a7a\u95f4\u3002\u8fd9\u5c31\u662f\u4e3a\u4ec0\u4e48\u8fd9\u4e2a\u5783\u573e\u56de\u6536\u5668\u53eb G1 Garbage-First\u3002<\/p>\n<p>\u987e\u540d\u601d\u4e49\uff0cG1 \u5c06\u6536\u96c6\u548c\u538b\u7f29\u6d3b\u52a8\u96c6\u4e2d\u5728\u5806\u4e2d\u53ef\u80fd\u5145\u6ee1\u53ef\u56de\u6536\u5bf9\u8c61\uff08\u5783\u573e\uff09\u7684\u533a\u57df\u3002G1 \u4f7f\u7528\u4e00\u4e2a\u6682\u505c\u9884\u6d4b\u6a21\u578b\u6765\u6ee1\u8db3\u7528\u6237\u9884\u8bbe\u7684\u505c\u987f\u65f6\u95f4\u76ee\u6807\uff0c\u5e76\u6839\u636e\u6307\u5b9a\u7684\u505c\u987f\u65f6\u95f4\u6765\u9009\u62e9\u8981\u6536\u96c6\u7684\u4e00\u7cfb\u5217\u533a\u57df\u3002<\/p>\n<p>G1 \u4f7f\u7528\u6e05\u9664\u7b97\u6cd5\u6765\u56de\u6536\u88ab\u6807\u8bb0\u4e3a\u53ef\u56de\u6536\u7684\u533a\u57df\u3002G1 \u5c06 1 \u4e2a\u6216\u8005\u591a\u4e2a\u533a\u57df\u7684\u5b58\u6d3b\u5bf9\u8c61\u62f7\u8d1d\u5230\u53e6\u4e00\u4e2a\u5355\u72ec\u7684\u533a\u57df\u3002\u5728\u8fd9\u4e2a\u8fc7\u7a0b\u4e2d\uff0c\u5373\u538b\u7f29\u4e86\u5185\u5b58\u53c8\u91ca\u653e\u4e86\u5185\u5b58\u3002\u8fd9\u4e2a\u6e05\u9664\u64cd\u4f5c\u5728\u591a\u5904\u7406\u5668\u4e0a\u5e76\u884c\u6267\u884c\uff0c\u4ee5\u51cf\u5c11\u505c\u987f\u65f6\u95f4\u5e76\u63d0\u9ad8\u541e\u5410\u91cf\u3002\u56e0\u6b64\uff0c\u5bf9\u4e8e\u6bcf\u4e2a\u533a\u57df\u7684\u5783\u573e\u56de\u6536\uff0cG1 \u6301\u7eed\u4e0d\u65ad\u51cf\u5c11\u788e\u7247\uff0c\u4e14\u5728\u7528\u6237\u5b9a\u4e49\u7684\u505c\u987f\u65f6\u95f4\u5185\u5de5\u4f5c\u3002\u8fd9\u8d85\u51fa\u4e86\u524d\u9762\u4e24\u79cd\u5783\u573e\u56de\u6536\u5668\u7684\u80fd\u529b\u3002CMS \u56de\u6536\u5668\u56de\u6536\u7684\u65f6\u5019\u4e0d\u538b\u7f29\u3002ParallelOld \u56de\u6536\u5668\u56de\u6536\u7684\u65f6\u5019\u538b\u7f29\u6574\u4e2a\u5806\uff0c\u8fd9\u4e0d\u53ef\u907f\u514d\u9020\u6210\u5f88\u5927\u7684\u505c\u987f\u65f6\u95f4\u3002<\/p>\n<p>G1 \u4e0d\u662f\u4e00\u4e2a\u5b9e\u65f6\u5783\u573e\u56de\u6536\u5668\uff0c\u77e5\u9053\u8fd9\u70b9\u5f88\u91cd\u8981\u3002\u8fd9\u610f\u5473\u7740\u53ef\u4ee5\u5f88\u5927\u6982\u7387\u6ee1\u8db3\u7528\u6237\u8bbe\u5b9a\u7684\u505c\u987f\u65f6\u95f4\uff0c\u4f46\u4e0d\u662f 100% \u4fdd\u8bc1\u80fd\u8fbe\u5230\u3002\u57fa\u4e8e\u8fc7\u53bb\u7684\u56de\u6536\u6570\u636e\uff0cG1 \u8bc4\u4f30\u56de\u6536\u591a\u5c11 region\uff0c\u53ef\u4ee5\u8fbe\u5230\u7528\u6237\u8bbe\u5b9a\u7684\u505c\u987f\u65f6\u95f4\u3002\u56e0\u6b64\uff0c\u56de\u6536\u5668\u5bf9\u4e8e\u624b\u673a\u533a\u57df\u7684\u6210\u672c\u6709\u4e00\u4e2a\u76f8\u5f53\u7cbe\u786e\u7684\u6a21\u578b\uff0c\u4ed6\u4f7f\u7528\u8fd9\u4e2a\u6a21\u578b\u6765\u51b3\u5b9a\u5728\u786e\u5b9a\u505c\u987f\u65f6\u95f4\u76ee\u6807\u4e0b\uff0c\u6536\u96c6\u54ea\u4e9b\u533a\u57df\u4ee5\u53ca\u6536\u96c6\u591a\u5c11\u4e2a\u533a\u57df\u3002<\/p>\n<p>\u6ce8\u610f: G1 \u6709\u5e76\u53d1(\u4e0e\u5e94\u7528\u7a0b\u5e8f\u7ebf\u7a0b\u4e00\u8d77\u8fd0\u884c\uff0c\u4f8b\u5982\uff0c\u7ec6\u5316\u3001\u6807\u8bb0\u3001\u6e05\u7406)\u548c\u5e76\u884c(\u591a\u7ebf\u7a0b\uff0c\u4f8b\u5982\uff0c\u505c\u6b62\u4e16\u754c)\u4e24\u4e2a\u9636\u6bb5\u3002\u5b8c\u6574\u7684\u5783\u573e\u6536\u96c6\u4ecd\u7136\u662f\u5355\u7ebf\u7a0b\u7684\uff0c\u4f46\u662f\u5982\u679c\u9002\u5f53\u8c03\u4f18\uff0c\u60a8\u7684\u5e94\u7528\u7a0b\u5e8f\u5e94\u8be5\u907f\u514d\u5b8c\u6574\u7684gc\u3002<\/p>\n<h3>1.2 G1 \u8db3\u8ff9<\/h3>\n<p>\u5982\u679c\u60a8\u4ece ParallelOldGC  CMS \u96c6\u5668\u8fc1\u79fb\u5230G1\uff0c\u60a8\u53ef\u80fd\u4f1a\u770b\u5230\u66f4\u5927\u7684 JVM \u8fdb\u7a0b\u3002\u8fd9\u5728\u5f88\u5927\u7a0b\u5ea6\u4e0a\u4e0e\u201c\u4f1a\u8ba1\u201d\u6570\u636e\u7ed3\u6784\u6709\u5173\uff0c\u5982 \u6807\u8bb0\u96c6\u5408\uff08rSet\uff09 \u548c \u56de\u6536\u96c6\u5408\uff08cSet\uff09\u3002<\/p>\n<h3>1.3 \u63a8\u8350\u4f7f\u7528 G1 \u7684\u573a\u666f<\/h3>\n<p>G1 \u7684\u7b2c\u4e00\u4e2a\u91cd\u70b9\u5c31\u662f\u9488\u5bf9\u8fd9\u6837\u7684\u573a\u666f\uff1a\u8981\u6c42\u8fd0\u884c\u9700\u8981\u5927\u5806\u4e14 GC \u5ef6\u8fdf\u6709\u9650\u7684\u5e94\u7528\u3002\u8fd9\u610f\u5473\u7740\u5806\u5927\u5c0f\u5728 6GB \u5de6\u53f3\u6216\u8005\u66f4\u5927\uff0c\u7a33\u5b9a\u548c\u53ef\u9884\u6d4b\u505c\u987f\u65f6\u95f4\u5728 0.5 \u79d2\u4ee5\u4e0b\u3002<\/p>\n<p>\u4e0d\u7ba1\u662f\u4f7f\u7528 CMS \u8fd8\u662f ParallelOld \u56de\u6536\u5668\u7684\u5e94\u7528\uff0c\u5982\u679c\u6709\u4ee5\u4e0b\u7279\u70b9\uff0c\u5207\u6362\u6210 G1\uff0c\u4f1a\u6709\u4e00\u5b9a\u7684\u6536\u76ca\uff1a<\/p>\n<ul>\n<li>Full GC \u8017\u65f6\u592a\u957f\u6216\u8005\u592a\u9891\u7e41\u3002<\/li>\n<li>\u5bf9\u8c61\u5206\u914d\u7387\u6216\u63d0\u5347\u7387\u5dee\u5f02\u8f83\u5927\u3002<\/li>\n<li>\u56de\u6536\u6216\u8005\u538b\u7f29\u505c\u987f\u65f6\u95f4\u592a\u957f\uff08\u8d85\u8fc7 0.5 \u6216\u8005 1 \u79d2\uff09<\/li>\n<\/ul>\n<p>\u6ce8\u610f:\u5982\u679c\u60a8\u6b63\u5728\u4f7f\u7528 CMS \u6216 ParallelOldGC\uff0c\u5e76\u4e14\u60a8\u7684\u5e94\u7528\u7a0b\u5e8f\u6ca1\u6709\u7ecf\u5386\u957f\u65f6\u95f4\u7684\u5783\u573e\u6536\u96c6\u6682\u505c\uff0c\u90a3\u4e48\u4f7f\u7528\u5f53\u524d\u7684\u6536\u96c6\u5668\u662f\u53ef\u4ee5\u7684\u3002\u66f4\u6539\u5230 G1 \u6536\u96c6\u5668\u5e76\u4e0d\u662f\u4f7f\u7528\u6700\u65b0 JDK \u7684\u5fc5\u8981\u6761\u4ef6\u3002<\/p>\n<h2>2 \u56de\u987e CMS \u5783\u573e\u56de\u6536\u5668<\/h2>\n<h3>2.1 \u56de\u987e\u5206\u4ee3 GC \u548c CMS<\/h3>\n<p>The Concurrent Mark Sweep (CMS) \u56de\u6536\u5668\uff08\u4e5f\u79f0\u4e3a\u5e76\u53d1\u4f4e\u6682\u505c\u56de\u6536\u5668\uff09\u6536\u96c6\u8001\u5e74\u4ee3\uff08tenured\uff09\u3002\u5b83\u901a\u8fc7\u8ba9\u5927\u90e8\u5206\u5783\u573e\u56de\u6536\u5de5\u4f5c\u548c\u7528\u6237\u7ebf\u7a0b\u5e76\u884c\uff0c\u8bd5\u56fe\u6700\u5c0f\u5316\u7531\u5783\u573e\u56de\u6536\u5f15\u8d77\u7684\u505c\u987f\u65f6\u95f4\u3002\u901a\u5e38\uff0cCMS \u4e0d\u4f1a\u590d\u5236\u548c\u538b\u7f29\u5b58\u6d3b\u5bf9\u8c61\u3002\u8fd9\u662f\u4e00\u4e2a\u4e0d\u4f1a\u79fb\u52a8\u5b58\u6d3b\u5bf9\u8c61\u7684\u5783\u573e\u56de\u6536\u5668\u3002\u5982\u679c\u788e\u7247\u6210\u4e3a\u4e00\u4e2a\u95ee\u9898\uff0c\u5206\u914d\u4e00\u4e2a\u66f4\u5927\u7684\u5806\u3002<\/p>\n<p>\u6ce8\u610f:\u5e74\u8f7b\u4ee3\u4e0a\u7684 CMS \u6536\u96c6\u5668\u4f7f\u7528\u4e0e\u5e76\u884c\u6536\u96c6\u5668\u76f8\u540c\u7684\u7b97\u6cd5\u3002<\/p>\n<h3>2.2 CMS \u56de\u6536\u9636\u6bb5<\/h3>\n<p>CMS\u6536\u96c6\u5668\u5728\u5806\u7684\u8001\u4e00\u4ee3\u4e0a\u6267\u884c\u4ee5\u4e0b\u9636\u6bb5:<\/p>\n<table>\n<thead>\n<tr>\n<th>\u9636\u6bb5<\/th>\n<th>\u63cf\u8ff0<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\u521d\u59cb\u6807\u8bb0\uff08STW\uff09<\/td>\n<td>\u8001\u4ee3\u4e2d\u7684\u5bf9\u8c61\uff0c\u5305\u62ec\u5e74\u8f7b\u4ee3\u4e2d\u53ef\u80fd\u53ef\u8bbf\u95ee\u7684\u5bf9\u8c61\u88ab\u201c\u6807\u8bb0\u201d\u4e3a\u53ef\u8bbf\u95ee\uff08\u53ef\u8fbe\u6027\u5206\u6790\u7684\u53ef\u8fbe\uff09\u3002\u76f8\u5bf9\u4e8e\u8f83\u5c0f\u7684\u6536\u96c6\u6682\u505c\u65f6\u95f4\uff0c\u8fd9\u4e2a\u9636\u6bb5\u6682\u505c\u65f6\u95f4\u7684\u6301\u7eed\u65f6\u95f4\u901a\u5e38\u8f83\u77ed\u3002<\/td>\n<\/tr>\n<tr>\n<td>\u5e76\u53d1\u6807\u8bb0<\/td>\n<td>\u5728\u7528\u6237\u7ebf\u7a0b\u5728\u6267\u884c\u7684\u540c\u4e8b\uff0c\u904d\u5386\u8001\u5e74\u4ee3\u4e2d\u7684\u5bf9\u8c61\u56fe\u4ee5\u67e5\u627e\u53ef\u8fbe\u5bf9\u8c61\u3002\u4ece\u5df2\u6807\u8bb0\u5bf9\u8c61\u5f00\u59cb\u626b\u63cf\uff0c\u4e14\u904d\u5386\u6807\u8bb0\u4ece root \u5bf9\u8c61\u5f00\u59cb\u53ef\u8fbe\u7684\u5bf9\u8c61\u3002<strong>\u5728\u9636\u6bb52\u30013\u30015\u4e2d\u65b0\u589e\u7684\u5bf9\u8c61\uff0c\u8fd8\u6709\u8fd9\u4e9b\u9636\u6bb5\u8fc7\u7a0b\u4e2d\u88ab\u5206\u914d\u7684\u5bf9\u8c61\u9a6c\u4e0a\u88ab\u6807\u8bb0\u4e3a\u5b58\u6d3b\u5bf9\u8c61<\/strong>\u3002<\/td>\n<\/tr>\n<tr>\n<td>\u91cd\u65b0\u6807\u8bb0\uff08STW\uff09<\/td>\n<td>\u67e5\u627e\u5e76\u53d1\u6807\u8bb0\u9636\u6bb5\u7531\u4e8e Java \u5e94\u7528\u7a0b\u5e8f\u7ebf\u7a0b\u5728\u5e76\u53d1\u6536\u96c6\u5668\u5b8c\u6210\u8ddf\u8e2a\u5bf9\u8c61\u4e4b\u540e\u5bf9\u5bf9\u8c61\u8fdb\u884c\u66f4\u65b0\u800c\u9057\u6f0f\u7684\u5bf9\u8c61\u3002<\/td>\n<\/tr>\n<tr>\n<td>\u5e76\u53d1\u6e05\u9664<\/td>\n<td>\u6536\u96c6\u5728\u6807\u8bb0\u9636\u6bb5\u6807\u8bc6\u4e3a\u4e0d\u53ef\u8fbe\u7684\u5bf9\u8c61\u3002\u6b7b\u5bf9\u8c61\uff08\u4e0d\u53ef\u8fbe\u5bf9\u8c61\uff09\u7684\u96c6\u5408\u5c06\u8be5\u5bf9\u8c61\u7684\u7a7a\u95f4\u6dfb\u52a0\u5230\u7a7a\u95f2\u5217\u8868\u4e2d\uff0c\u4ee5\u4f9b\u4ee5\u540e\u5206\u914d\u3002\u6b7b\u4ea1\u5bf9\u8c61\u7684\u5408\u5e76\u53ef\u80fd\u53d1\u751f\u5728\u8fd9\u4e00\u70b9\u4e0a\u3002\u6ce8\u610f\uff0c\u53ef\u8fbe\u5bf9\u8c61\u4e0d\u4f1a\u79fb\u52a8\u3002<\/td>\n<\/tr>\n<tr>\n<td>\u91cd\u7f6e<\/td>\n<td>\u901a\u8fc7\u6e05\u9664\u6570\u636e\u7ed3\u6784\u4e3a\u4e0b\u4e00\u6b21\u5e76\u53d1\u6536\u96c6\u505a\u51c6\u5907\u3002<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>2.3 \u56de\u987e\u5783\u573e\u56de\u6536\u6b65\u9aa4<\/h3>\n<ol>\n<li>CMS \u56de\u6536\u5668\u7684\u5806\u7ed3\u6784<\/li>\n<\/ol>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722749\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u5e74\u8f7b\u4ee3\u88ab\u5206\u4e3a eden \u533a\u548c\u4e24\u4e2a survivor \u533a\u57df\u3002\u8001\u5e74\u4ee3\u662f\u4e00\u4e2a\u8fde\u7eed\u7684\u7a7a\u95f4\u3002\u5bf9\u8c61\u5728\u539f\u5730\u88ab\u56de\u6536\u3002\u9664\u975e\u6709 fullGC\uff0c\u5426\u5219\u4e0d\u4f1a\u6709\u538b\u7f29\u3002<\/p>\n<ol start=\"2\">\n<li>CMS \u4e2d\u5e74\u8f7b\u4ee3 GC \u662f\u600e\u4e48\u5de5\u4f5c\u7684<\/li>\n<\/ol>\n<p>\u5e74\u8f7b\u4ee3\u88ab\u6807\u8bb0\u4e3a\u7eff\u8272\uff0c\u8001\u5e74\u4ee3\u6807\u8bb0\u4e3a\u84dd\u8272\u3002\u4e0b\u56fe\u53ef\u80fd\u5c31\u662f\u5e94\u7528\u7a0b\u5e8f\u5df2\u7ecf\u8fd0\u884c\u4e00\u6bb5\u65f6\u95f4\u4e4b\u540e CMS \u5185\u7684\u6837\u5b50\u3002\u5bf9\u8c61\u5206\u6563\u5728\u8001\u4ee3\u533a\u57df\u5468\u56f4\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722750\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u4f7f\u7528 CMS\uff0c\u8001\u5e74\u4ee3\u5bf9\u8c61\u88ab\u539f\u5730\u91ca\u653e\u3002\u5b83\u4eec\u4e0d\u4f1a\u88ab\u79fb\u52a8\u3002\u9664\u975e\u6709\u4e00\u4e2a\u5b8c\u6574\u7684GC\uff0c\u5426\u5219\u7a7a\u95f4\u4e0d\u4f1a\u88ab\u538b\u7f29\u3002<\/p>\n<ol start=\"3\">\n<li>\u5e74\u8f7b\u4ee3\u6536\u96c6<\/li>\n<\/ol>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722751\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u6d3b\u52a8\u5bf9\u8c61\u4ece eden \u533a\u548c S(survior)\u533a\u57df \u590d\u5236\u5230\u53e6\u4e00\u4e2a S \u7a7a\u95f4\u3002\u4efb\u4f55\u5df2\u7ecf\u8fbe\u5230\u8001\u5316\u9608\u503c\uff08\u9ed8\u8ba4\u914d\u7f6e\u662f 15\uff09\u7684\u65e7\u5bf9\u8c61\u90fd\u88ab\u63d0\u5347\u5230\u8001\u5e74\u4ee3\u3002<\/p>\n<ol start=\"4\">\n<li>\u5e74\u8f7b\u4ee3\u6536\u96c6\u5b8c\u4e4b\u540e<\/li>\n<\/ol>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722752\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>eden \u533a\u57df\u88ab\u6e05\u7a7a\uff0c\u4ee5\u53ca\u5176\u4e2d\u4e00\u4e2a S \u533a\u57df\u88ab\u6e05\u7a7a\u3002<\/p>\n<p>\u65b0\u63d0\u5347\u5230\u8001\u5e74\u4ee3\u7684\u5bf9\u8c61\u5728\u56fe\u4e2d\u663e\u793a\u4e3a\u6df1\u84dd\u8272\u3002\u7eff\u8272\u7684\u5bf9\u8c61\u662f\u8fd8\u6ca1\u6709\u63d0\u5347\u5230\u8001\u5e74\u4ee3\u7684\u5e74\u8f7b\u4ee3\u5bf9\u8c61\u3002<\/p>\n<ol start=\"5\">\n<li>\u7528 CMS \u6536\u96c6\u8001\u5e74\u4ee3<\/li>\n<\/ol>\n<p>\u53d1\u751f STW \u7684\u4e24\u4e2a\u65f6\u95f4\u70b9:\u521d\u59cb\u6807\u8bb0\u548c\u91cd\u65b0\u6807\u8bb0\u3002\u5f53\u8001\u5e74\u4ee3\u7a7a\u95f4\u5360\u7528\u7387\u8fbe\u5230\u4e00\u5b9a\u7684\u6bd4\u7387\uff08\u53ef\u914d\u7f6e\uff09\u65f6\uff0cCMS \u5783\u573e\u6536\u96c6\u542f\u52a8\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722753\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\uff081\uff09\u521d\u59cb\u6807\u8bb0\u662f\u4e00\u4e2a\u77ed\u6682\u7684\u6682\u505c\u9636\u6bb5\uff0c\u8fd9\u9636\u6bb5\u6807\u8bb0\u53ef\u89e6\u8fbe\u7684\u5bf9\u8c61\uff1b\uff082\uff09\u5e76\u53d1\u6807\u8bb0\u627e\u5230\u5e94\u7528\u7ee7\u7eed\u8fd0\u884c\u671f\u95f4\u53ef\u89e6\u8fbe\u7684\u5bf9\u8c61\uff1b\uff083\uff09\u6700\u540e\uff0c\u91cd\u65b0\u6807\u8bb0\u9636\u6bb5\uff0c\u67e5\u627e\u5728\u7b2c\uff082\uff09\u9636\u6bb5\u9057\u6f0f\u7684\u5bf9\u8c61\u3002<\/p>\n<ol start=\"6\">\n<li>\u8001\u5e74\u4ee3\u6536\u96c6\u2014\u2014\u5e76\u53d1\u6e05\u7406<\/li>\n<\/ol>\n<p>\u672a\u5728\u524d\u9762\u51e0\u4e2a\u9636\u6bb5\u88ab\u6807\u8bb0\u7684\u5bf9\u8c61\u89c6\u4e3a\u5783\u573e\u5bf9\u8c61\uff0c\u4f1a\u88ab\u91ca\u653e\u3002\u6ca1\u6709\u538b\u7f29\u3002<\/p>\n<p>\u6ce8\u610f\uff1a\u672a\u6807\u8bb0\u5bf9\u8c61 == \u6b7b\u4ea1\u5bf9\u8c61<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722754\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<ol start=\"7\">\n<li>\u8001\u5e74\u4ee3\u6536\u96c6\u2014\u2014\u6e05\u7406\u4e4b\u540e<\/li>\n<\/ol>\n<p>\u5728\u6e05\u7406\u9636\u6bb5\u5b8c\u6210\u4e4b\u540e\uff0c\u4f60\u53ef\u4ee5\u770b\u5230\u5f88\u591a\u7684\u5185\u5b58\u533a\u57df\u90fd\u88ab\u91ca\u653e\u51fa\u6765\u4e86\u3002\u4f60\u80fd\u6ce8\u610f\u5230\u4e00\u76f4\u6ca1\u6709\u8fdb\u884c\u538b\u7f29\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722755\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u6700\u540e\uff0cCMS\u6536\u96c6\u5668\u5c06\u901a\u8fc7(5)\u91cd\u8bbe\u9636\u6bb5\uff0c\u7b49\u5f85\u4e0b\u4e00\u6b21\u8fbe\u5230 GC \u9608\u503c\u3002<\/p>\n<h2>3 G1 \u5783\u573e\u56de\u6536\u7684\u6b65\u9aa4<\/h2>\n<p>G1 \u6536\u96c6\u5668\u4f7f\u7528\u4e00\u79cd\u4e0d\u540c\u7684\u65b9\u6cd5\u56de\u6536\u5806\u5bf9\u8c61\u3002\u4e0b\u9762\u7684\u56fe\u7247\u5c06\u4e00\u6b65\u4e00\u6b65\u7ed9\u4f60\u5c55\u793a G1 \u56de\u6536\u6b65\u9aa4\u3002<\/p>\n<ol>\n<li>G1 \u5806\u7ed3\u6784<\/li>\n<\/ol>\n<p>\u5806\u662f\u4e00\u5757\u56fa\u5b9a\u7684\u5185\u5b58\u533a\u57df\uff0c\u5b83\u88ab\u5212\u5206\u4e3a\u56fa\u5b9a\u5927\u5c0f\u7684\u5c0f\u533a\u57df\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722756\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u5c0f\u533a\u57df\u5927\u5c0f\u901a\u8fc7 JVM \u542f\u52a8\u7684\u65f6\u5019\u8bbe\u5b9a\u3002JVM \u901a\u5e38\u4ee5 2000 \u4e2a\u533a\u57df\u4e3a\u76ee\u6807\uff0c\u5927\u5c0f\u4ece 1 \u5230 32Mb \u4e0d\u7b49\u3002<\/p>\n<ol start=\"2\">\n<li>G1 \u5806\u5206\u914d<\/li>\n<\/ol>\n<p>\u4e8b\u5b9e\u4e0a\uff0c\u8fd9\u4e9b\u533a\u57df\u88ab\u903b\u8f91\u5212\u5206\u4e3a eden\u3001survivor \u548c\u8001\u5e74\u4ee3\u533a\u57df\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722757\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u56fe\u7247\u4e2d\u7684\u989c\u8272\u663e\u793a\u4e86\u54ea\u4e2a\u533a\u57df\u4e0e\u54ea\u4e2a\u89d2\u8272\u76f8\u5173\u8054\u3002\u6d3b\u52a8\u5bf9\u8c61\u88ab\u4ece\u4e00\u4e2a\u533a\u57df\u758f\u6563(\u5373\u590d\u5236\u6216\u79fb\u52a8)\u5230\u53e6\u4e00\u4e2a\u533a\u57df\u3002\u5728\u505c\u6b62\uff08STW\uff09\u6216\u8005\u4e0d\u505c\u6b62\u7528\u6237\u7ebf\u7a0b\u7684\u60c5\u51b5\u4e0b\uff0c\u533a\u57df\u88ab\u8bbe\u8ba1\u6210\u4e0e\u6240\u6709\u5176\u4ed6\u5e94\u7528\u7a0b\u5e8f\u7ebf\u7a0b\u5e76\u884c\u6536\u96c6\u3002<\/p>\n<p>\u5982\u56fe\u6240\u793a\uff0c\u53ef\u4ee5\u5c06\u533a\u57df\u5206\u914d\u4e3aEden\u3001survivor\u548c\u8001\u5e74\u4ee3\u533a\u57df\u3002\u6b64\u5916\uff0c\u8fd8\u6709\u7b2c\u56db\u79cd\u7c7b\u578b\u7684\u533a\u57df\u88ab\u79f0\u4e3a\u5927\u5bf9\u8c61\u533a\u57df\u3002\u8fd9\u4e9b\u533a\u57df\u88ab\u8bbe\u8ba1\u7528\u6765\u5bb9\u7eb3\u6807\u51c6\u533a\u57df\u5927\u5c0f\u7684 50% \u6216\u66f4\u5927\u7684\u5bf9\u8c61\u3002\u5b83\u4eec\u88ab\u5b58\u50a8\u4e3a\u4e00\u7ec4\u76f8\u90bb\u7684\u533a\u57df\u3002\u6700\u540e\u4e00\u79cd\u7c7b\u578b\u7684\u533a\u57df\u53ef\u80fd\u662f\u5806\u4e2d\u672a\u4f7f\u7528\u7684\u533a\u57df\u3002<\/p>\n<p>\u6ce8\u610f:\u5728\u64b0\u5199\u672c\u6587\u65f6\uff0c\u6536\u96c6\u5927\u5bf9\u8c61\u8fd8\u6ca1\u6709\u4f18\u5316\u3002\u56e0\u6b64\uff0c\u5e94\u8be5\u907f\u514d\u521b\u5efa\u8fd9\u79cd\u5927\u5c0f\u7684\u5bf9\u8c61\u3002<\/p>\n<ol start=\"3\">\n<li>\u7528 G1 \u6536\u96c6\u5e74\u8f7b\u4ee3<\/li>\n<\/ol>\n<p>\u6574\u4e2a\u5806\u88ab\u5206\u4e3a\u5c06\u8fd1 2000 \u4e2a\u533a\u57df\u3002\u6700\u5c0f\u7684 1M\uff0c\u6700\u5927\u7684 32 M\u3002\u84dd\u8272\u533a\u57df\u6301\u6709\u8001\u5e74\u4ee3\u5bf9\u8c61\uff0c\u7eff\u8272\u533a\u57df\u6301\u6709\u5e74\u8f7b\u4ee3\u5bf9\u8c61\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722758\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u6ce8\u610f\uff1a\u76f8\u6bd4\u4e8e\u4ee5\u524d\u7684\u5783\u573e\u56de\u6536\u5668\u6765\u8bf4\uff0c\u533a\u57df\u4e0d\u5f3a\u5236\u8981\u6c42\u7a7a\u95f4\u8fde\u7eed\u3002<\/p>\n<ol start=\"4\">\n<li>G1 \u7684\u5e74\u8f7b\u4ee3\u5783\u573e\u56de\u6536<\/li>\n<\/ol>\n<p>\u5b58\u6d3b\u5bf9\u8c61\u88ab\u758f\u6563\uff08\u590d\u5236\u6216\u8005\u79fb\u52a8\uff09\u5230\u4e00\u4e2a\u6216\u8005\u591a\u4e2a survivor \u533a\u57df\u3002\u5982\u679c\u8d85\u8fc7\u5e74\u9f84\u9608\u503c\uff0c\u4e00\u4e9b\u5bf9\u8c61\u4f1a\u88ab\u63d0\u5347\u5230\u8001\u5e74\u4ee3\u533a\u57df\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722759\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u8fd9\u4e2a\u65b9\u6cd5\u4f7f\u5f97\u91cd\u65b0\u8bbe\u7f6e\u533a\u57df\u5927\u5c0f\u66f4\u5bb9\u6613\uff0c\u8ba9\u4ed6\u4eec\u66f4\u5927\u6216\u8005\u66f4\u5c0f\u4e5f\u662f\u5fc5\u987b\u7684\u3002<\/p>\n<p>\u8fd9\u4e2a\u9636\u6bb5\u4f1a\u53d1\u751f STW\u3002eden \u548c survivor \u533a\u57df\u4e3a\u4e86\u4e0b\u6b21\u5e74\u8f7b\u4ee3 GC\uff0c\u5927\u5c0f\u4f1a\u88ab\u8ba1\u7b97\u3002\u8ba1\u7b97\u4fe1\u606f\u4f1a\u88ab\u4fdd\u5b58\uff0c\u4ee5\u5e2e\u52a9\u8ba1\u7b97\u5927\u5c0f\u3002\u76ee\u6807\u505c\u987f\u65f6\u95f4\u7b49\u4f1a\u88ab\u8003\u8651\u8fdb\u53bb\u3002<\/p>\n<ol start=\"5\">\n<li>\u7ed3\u675f\u5e74\u8f7b\u4ee3\u5783\u573e\u56de\u6536<\/li>\n<\/ol>\n<p>\u5b58\u6d3b\u5bf9\u8c61\u5df2\u7ecf\u88ab\u758f\u6563\u5230 survivor \u533a\u57df\u6216\u8005\u8001\u5e74\u4ee3\u533a\u57df\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722760\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u73b0\u5728\u63d0\u5347\u5230\u8001\u5e74\u4ee3\u5bf9\u8c61\u6807\u8bb0\u4e3a\u6df1\u84dd\u8272\u3002survivor \u533a\u57df\u88ab\u6807\u8bb0\u4e3a\u7eff\u8272\u3002<\/p>\n<p>\u603b\u7ed3\uff0c\u5e74\u8f7b\u4ee3\u5783\u573e\u56de\u6536\uff1a<\/p>\n<ul>\n<li>\u5806\u662f\u4e00\u6574\u5757\u533a\u57df\uff0c\u4f46\u88ab\u5206\u4e3a\u66f4\u5c0f\u7684\u533a\u57df\u3002<\/li>\n<li>\u5e74\u8f7b\u4ee3\u5185\u5b58\u662f\u4e00\u7cfb\u5217\u4e0d\u8fde\u7eed\u7684\u533a\u57df\u7ec4\u6210\u7684\u3002\u8fd9\u8ba9\u8c03\u6574\u5927\u5c0f\u53d8\u5f97\u66f4\u5bb9\u6613\u3002<\/li>\n<li>\u5e74\u8f7b\u4ee3\u5783\u573e\u56de\u6536\uff0c\u4f1a\u53d1\u751f STW\u3002\u5e74\u8f7b\u4ee3\u5783\u573e\u56de\u6536\u4f1a\u505c\u6b62\u6240\u6709\u7528\u6237\u7ebf\u7a0b\u3002<\/li>\n<li>\u5e74\u8f7b\u4ee3\u5783\u573e\u56de\u6536\u4f60\u7528\u591a\u4e2a\u7ebf\u7a0b\u5e76\u53d1\u6267\u884c\u7684\u3002<\/li>\n<li>\u5b58\u6d3b\u5bf9\u8c61\u4f1a\u88ab\u590d\u5236\u5230 survivor \u533a\u57df\u6216\u8005\u8001\u5e74\u4ee3\u533a\u57df\u3002<\/li>\n<\/ul>\n<h3>3.1 G1 \u7684\u8001\u5e74\u4ee3\u56de\u6536<\/h3>\n<p>\u548c CMS \u56de\u6536\u5668\u4e00\u6837\uff0c\u5bf9\u4e8e\u6536\u96c6\u8001\u5e74\u4ee3\uff0cG1 \u56de\u6536\u5668\u76ee\u6807\u4e5f\u662f\u6210\u4e3a\u4e00\u4e2a\u4f4e\u505c\u987f\u65f6\u95f4\u7684\u5783\u573e\u56de\u6536\u5668\u3002\u4e0b\u9762\u7684\u8868\u683c\u63cf\u8ff0\u4e86 G1 \u7684\u5404\u4e2a\u9636\u6bb5\u3002<\/p>\n<p>G1 \u6536\u96c6\u8001\u5e74\u4ee3\u7684\u65f6\u5019\uff0c\u6709\u4ee5\u4e0b\u9636\u6bb5\u3002\u6ce8\u610f\uff1a\u6709\u4e9b\u9636\u6bb5\u662f\u5e74\u8f7b\u4ee3\u5783\u573e\u56de\u6536\u7684\u4e00\u90e8\u5206\u3002<\/p>\n<table>\n<thead>\n<tr>\n<th>\u9636\u6bb5<\/th>\n<th>\u63cf\u8ff0<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\uff081\uff09\u521d\u59cb\u6807\u8bb0\uff08STW\uff09<\/td>\n<td>\u8fd9\u4e2a\u9636\u6bb5\u4f1a\u53d1\u751fSTW\uff0c\u4e5f\u662f\u5e74\u8f7b\u4ee3\u5783\u573e\u56de\u6536\u7684\u4e00\u6b65\u3002\u6807\u8bb0\u5b58\u6d3b\u533a\u57df\uff08\u6839\u533a\u57df\uff09\uff0c\u8fd9\u4e9b\u533a\u57df\u53ef\u80fd\u6709\u5bf9\u8001\u5e74\u4ee3\u5bf9\u8c61\u7684\u5f15\u7528\u3002<\/td>\n<\/tr>\n<tr>\n<td>\uff082\uff09\u6839\u533a\u57df\u626b\u63cf<\/td>\n<td>\u626b\u63cf survivor \u533a\u57df\uff0c\u67e5\u627e\u5230\u8001\u5e74\u4ee3\u7684\u5f15\u7528\u3002\u8fd9\u548c\u7528\u6237\u7ebf\u7a0b\u540c\u65f6\u8fdb\u884c\u3002\u8fd9\u4e2a\u9636\u6bb5\u5fc5\u987b\u5728\u5e74\u8f7b\u4ee3\u5783\u573e\u56de\u6536\u53d1\u751f\u4e4b\u524d\u3002<\/td>\n<\/tr>\n<tr>\n<td>\uff083\uff09\u5e76\u53d1\u6807\u8bb0<\/td>\n<td>\u67e5\u627e\u6574\u4e2a\u5806\u4e2d\u7684\u5b58\u6d3b\u5bf9\u8c61\u3002\u8fd9\u548c\u7528\u6237\u7ebf\u7a0b\u540c\u65f6\u8fdb\u884c\u3002\u8fd9\u4e2a\u9636\u6bb5\u53ef\u4ee5\u88ab\u5e74\u8f7b\u4ee3\u5783\u573e\u56de\u6536\u6253\u65ad\u3002<\/td>\n<\/tr>\n<tr>\n<td>\uff084\uff09\u91cd\u65b0\u6807\u8bb0\uff08STW\uff09<\/td>\n<td>\u5b8c\u6210\u5806\u4e2d\u5b58\u6d3b\u5bf9\u8c61\u7684\u6807\u8bb0\u3002\u4f7f\u7528\u4e00\u4e2a\u53ebSATB(snapshot-at-the-beginnint)\u7684\u7b97\u6cd5\uff0c\u8fd9\u4e2a\u7b97\u6cd5\u6bd4 CMS \u4e2d\u7528\u7684\u7b97\u6cd5\u5feb\u3002<\/td>\n<\/tr>\n<tr>\n<td>\uff085\uff09\u6e05\u9664\uff08STW\u4e14\u548c\u7528\u6237\u7ebf\u7a0b\u5e76\u53d1\uff09<\/td>\n<td>1\uff09\u5bf9\u5b58\u6d3b\u5bf9\u8c61\u548c\u7a7a\u533a\u57df\u8fdb\u884c\u8ba1\u7b97\u3002\uff08STW\uff09\u30022\uff09\u6e05\u9664\u8bb0\u5f55\u96c6\uff08STW\uff09\u3010\u5565\u610f\u601d\uff1f\u3011\u30023\uff09\u91cd\u8bbe\u7a7a\u533a\u57df\u5e76\u5c06\u5176\u8fd4\u56de\u7a7a\u95f2\u5217\u8868\uff08\u5e76\u53d1\uff09<\/td>\n<\/tr>\n<tr>\n<td>\uff08*\uff09\u590d\u5236\uff08STW\uff09<\/td>\n<td>\u8fd9\u4e2a\u9636\u6bb5\uff0c\u8ba1\u7b97\u505c\u987f\u65f6\u95f4\u5e76\u590d\u5236\u5b58\u6d3b\u5bf9\u8c61\u5230\u65b0\u7684\u672a\u4f7f\u7528\u533a\u57df\u3002\u8fd9\u53ef\u4ee5\u4f7f\u7528\u5e74\u8f7b\u4ee3\u5b8c\u6210\uff0clog\u6807\u8bb0\u4e3a[GC Pause (young)]\u3002\u6216\u8005\u4f7f\u7528\u5e74\u8f7b\u4ee3\u548c\u8001\u5e74\u4ee3\uff0clog\u6807\u8bb0\u4e3a[GC Pause(mixed)]<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\u4ee5\u4e0b\u4e3a\u8001\u5e74\u4ee3\u56de\u6536\u7684\u6b65\u9aa4\uff1a<\/p>\n<p>\u5b9a\u4e49\u4e86\u8fd9\u4e9b\u9636\u6bb5\u4e4b\u540e\uff0c\u8ba9\u6211\u4eec\u770b\u770b\u5b83\u4eec\u5982\u4f55\u4e0e G1 \u6536\u96c6\u5668\u4e2d\u7684\u8001\u4e00\u4ee3\u4ea4\u4e92\u3002<\/p>\n<ol start=\"6\">\n<li>\u521d\u59cb\u6807\u8bb0\u9636\u6bb5<\/li>\n<\/ol>\n<p>\u627f\u8f7d\u5230\u5e74\u8f7b\u4ee3\u5783\u573e\u56de\u6536\u4e4b\u4e0a\uff0c\u521d\u59cb\u6807\u8bb0\u9636\u6bb5\u6807\u8bb0\u5b58\u6d3b\u5bf9\u8c61\u3002log\u6807\u8bb0\u4e3a [GC pause (young) (initial-mark)]<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722761\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<ol start=\"7\">\n<li>\u5e76\u53d1\u6807\u8bb0\u9636\u6bb5<\/li>\n<\/ol>\n<p>\u5982\u679c\u53d1\u73b0\u7a7a\u533a\u57df\uff0c\u6807\u8bb0\u4e3a X\uff0c\u4ed6\u4eec\u5728\u91cd\u65b0\u6807\u8bb0\u9636\u6bb5\u88ab\u7acb\u5373\u5220\u9664\u3002\u5e76\u4e14\uff0c\u8fd9\u4e2a\u9636\u6bb5\u8fd8\u8ba1\u7b97\u4e86\u8868\u793a\u5b58\u6d3b\u529b\u7684\u201c\u4f1a\u8ba1\u201d\u4fe1\u606f\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722762\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<ol start=\"8\">\n<li>\u91cd\u65b0\u6807\u8bb0\u9636\u6bb5<\/li>\n<\/ol>\n<p>\u7a7a\u533a\u57df\u88ab\u5220\u9664\u548c\u56de\u6536\u3002\u6240\u6709\u7684\u533a\u57df\u6d3b\u529b\uff08\u6211\u7406\u89e3\u4e3a\u5b58\u6d3b\u5bf9\u8c61\u6bd4\u4f8b\uff09\u88ab\u8ba1\u7b97\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722763\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>PS\uff1a\u5bf9\u6bd4\u9636\u6bb5 7 \u6765\u770b\u8fd9\u5f20\u56fe\u3002<\/p>\n<ol start=\"9\">\n<li>\u590d\u5236\/\u6e05\u7406\u9636\u6bb5<\/li>\n<\/ol>\n<p>G1 \u4f1a\u9009\u62e9\u6d3b\u529b\u6700\u4f4e\u7684\u533a\u57df\uff0c\u8fd9\u4e9b\u533a\u57df\u80fd\u88ab\u66f4\u5feb\u7684\u56de\u6536\u3002\u7136\u540e\u5728\u5e74\u8f7b\u4ee3\u56de\u6536\u7684\u65f6\u5019\u540c\u65f6\u56de\u6536\u8fd9\u4e9b\u533a\u57df\u3002log \u6807\u8bb0\u4e3a[GC pause (mixed)]\u3002\u56e0\u6b64\u5e74\u8f7b\u4ee3\u548c\u8001\u5e74\u4ee3\u662f\u540c\u65f6\u56de\u6536\u7684\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722764\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<ol start=\"10\">\n<li>\u590d\u5236\/\u6e05\u7406\u9636\u6bb5\u4e4b\u540e<\/li>\n<\/ol>\n<p>\u88ab\u9009\u4e2d\u88ab\u6e05\u7406\u7684\u533a\u57df\uff0c\u88ab\u6e05\u7406\u548c\u538b\u7f29\u4e4b\u540e\u4f1a\u88ab\u6807\u8bb0\u4e3a\u6df1\u84dd\u8272\u533a\u57df\u548c\u6df1\u7eff\u8272\u533a\u57df\u3002\u5982\u4e0b\u56fe\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042722765\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<h3>3.2 \u603b\u7ed3\u8001\u5e74\u4ee3GC<\/h3>\n<p>\u4e00\u4e9b\u5173\u4e8e G1 \u8001\u5e74\u4ee3\u5783\u573e\u56de\u6536\u7684\u5173\u952e\u70b9\uff1a<\/p>\n<ul>\n<li>\u5e76\u53d1\u6807\u8bb0\u9636\u6bb5<\/li>\n<\/ul>\n<p>1\uff09\u6d3b\u529b\u8ba1\u7b97\u548c\u7528\u6237\u7ebf\u7a0b\u5e76\u884c<\/p>\n<p>2\uff09\u5728\u758f\u6563\u6682\u505c\u65f6\u95f4\u7684\u540c\u65f6\uff0c\u8ba1\u7b97\u54ea\u4e9b\u533a\u57df\u7684\u6d3b\u529b\u4fe1\u606f\u533a\u5206\u54ea\u4e9b\u533a\u57df\u8981\u88ab\u56de\u6536<\/p>\n<p>3\uff09\u6ca1\u6709\u50cf CMS \u7684\u6e05\u7406\u9636\u6bb5<\/p>\n<ul>\n<li>\u91cd\u65b0\u6807\u8bb0\u9636\u6bb5<\/li>\n<\/ul>\n<p>1\uff09\u4f7f\u7528 SATB \u7b97\u6cd5\uff0c\u8fd9\u79cd\u7b97\u6cd5\u6bd4 CMS \u7528\u7684\u7b97\u6cd5\u5feb\u5f97\u591a\u3002<\/p>\n<p>2\uff09\u5b8c\u5168\u7a7a\u7684\u533a\u57df\u88ab\u56de\u6536\uff0c\u867d\u7136\u8fd9\u4e2a\u9636\u6bb5\u53eb\u91cd\u65b0\u6807\u8bb0<\/p>\n<ul>\n<li>\u590d\u5236\/\u6e05\u7406\u9636\u6bb5<\/li>\n<\/ul>\n<p>1\uff09\u5e74\u8f7b\u4ee3\u548c\u8001\u5e74\u4ee3\u88ab\u540c\u65f6\u56de\u6536<\/p>\n<p>2\uff09\u8001\u5e74\u4ee3\u533a\u57df\u7684\u9009\u62e9\u662f\u57fa\u4e8e\u6d3b\u529b\u503c\u7684<\/p>\n<h2>4 \u6700\u4f73\u5b9e\u8df5\uff08\u5ffd\u7565\u547d\u4ee4\u884c\u64cd\u4f5c\u90e8\u5206\uff09<\/h2>\n<p>\u4e00\u4e9b\u4f60\u4f7f\u7528 G1\uff0c\u9700\u8981\u9075\u5faa\u7684\u5b9e\u8df5\u3002<\/p>\n<h3>4.1 \u4e0d\u8981\u8bbe\u7f6e\u5e74\u8f7b\u4ee3\u533a\u57df\u5927\u5c0f<\/h3>\n<p>\u901a\u8fc7 -Xmn \u663e\u5f0f\u8bbe\u7f6e\u5e74\u8f7b\u4ee3\u7684\u5927\u5c0f\u4f1a\u5e72\u6270G1\u6536\u96c6\u5668\u7684\u9ed8\u8ba4\u884c\u4e3a\u3002<\/p>\n<ul>\n<li>G1 \u4f1a\u4e0d\u518d\u5c0a\u91cd\u8bbe\u5b9a\u7684\u76ee\u6807\u505c\u987f\u65f6\u95f4\u3002\u6240\u4ee5\u672c\u8d28\u4e0a\uff0c\u8bbe\u7f6e\u5e74\u8f7b\u4ee3\u5927\u5c0f\u4e0e\u76ee\u6807\u505c\u987f\u65f6\u95f4\u51b2\u7a81\u3002<\/li>\n<li>G1 \u4e0d\u518d\u80fd\u591f\u6839\u636e\u9700\u8981\u6269\u5c55\u548c\u6536\u7f29\u5e74\u8f7b\u4ee3\u7a7a\u95f4\u3002\u7531\u4e8e\u5927\u5c0f\u662f\u56fa\u5b9a\u7684\uff0c\u6240\u4ee5\u4e0d\u80fd\u5bf9\u5927\u5c0f\u8fdb\u884c\u66f4\u6539\u3002<\/li>\n<\/ul>\n<h3>4.2 \u54cd\u5e94\u65f6\u95f4\u6307\u6807<\/h3>\n<p>\u4e0e\u5176\u4f7f\u7528\u5e73\u5747\u54cd\u5e94\u65f6\u95f4(ART)\u4f5c\u4e3a\u8bbe\u7f6e XX:MaxGCPauseMillis=&lt;N&gt; \u7684\u5ea6\u91cf\u6807\u51c6\uff0c\u4e0d\u5982\u8003\u8651\u8bbe\u7f6e\u5728 90% \u6216\u66f4\u591a\u7684\u65f6\u95f4\u5185\u6ee1\u8db3\u76ee\u6807\u7684\u503c\u3002\u8fd9\u6837\uff0c90% \u7684\u7528\u6237\u8bf7\u6c42\u4e0d\u4f1a\u7ecf\u5386\u6bd4\u76ee\u6807\u505c\u987f\u65f6\u95f4\u66f4\u957f\u7684\u505c\u987f\u3002\u8bb0\u4f4f\u4e00\u4ef6\u4e8b\uff0c\u76ee\u6807\u505c\u987f\u65f6\u95f4\u662f\u4e2a\u76ee\u6807\uff0c\u8fd9\u4e2a\u76ee\u6807\u4e0d\u4fdd\u8bc1 100% \u6ee1\u8db3\u3002<\/p>\n<h3>4.3 \u4ec0\u4e48\u662f\u758f\u6563\u5931\u8d25\uff1f<\/h3>\n<p>\u8fd9\u662f\u5f53 JVM \u5728\u5bf9 survivor \u5bf9\u8c61\u548c\u63d0\u5347\u5bf9\u8c61\u8fdb\u884c GC \u671f\u95f4\u8017\u5c3d\u5806\u533a\u57df\u65f6\u53d1\u751f\u7684\u63d0\u5347\u5931\u8d25\u3002\u5806\u5df2\u7ecf\u6ee1\u4e86\uff0c\u4e0d\u80fd\u518d\u6269\u5145\u4e86\u3002\u5982\u679c\u4f7f\u7528\u4e86\u53c2\u6570\uff1aXX:+PrintGCDetail\uff0c\u8fd9\u4e2a\u65f6\u5019 log \u4f1a\u6253\u5370 to-space overflow\u3002\u8fd9\u4e2a\u64cd\u4f5c\u662f\u6602\u8d35\u7684\u3002<\/p>\n<ul>\n<li>GC\u4ecd\u7136\u5fc5\u987b\u7ee7\u7eed\uff0c\u56e0\u6b64\u5fc5\u987b\u91ca\u653e\u7a7a\u95f4\u3002<\/li>\n<li>\u672a\u6210\u529f\u590d\u5236\u7684\u5bf9\u8c61\u5fc5\u987b\u88ab\u6c38\u4e45\u4fdd\u5b58\u5728\u9002\u5f53\u7684\u4f4d\u7f6e\u3002<\/li>\n<li>\u5bf9 CSet \u4e2d\u533a\u57df\u7684 rset \u7684\u4efb\u4f55\u66f4\u65b0\u90fd\u5fc5\u987b\u91cd\u65b0\u751f\u6210\u3002<\/li>\n<li>\u6240\u6709\u8fd9\u4e9b\u6b65\u9aa4\u90fd\u662f\u6602\u8d35\u7684\u3002<\/li>\n<\/ul>\n<h3>4.4 \u600e\u4e48\u907f\u514d\u758f\u6563\u5931\u8d25<\/h3>\n<p>\u8003\u8651\u4ee5\u4e0b\u64cd\u4f5c\u907f\u514d\u758f\u6563\u5931\u8d25<\/p>\n<ul>\n<li>\u63d0\u5347\u5806\u5927\u5c0f<\/li>\n<\/ul>\n<p>1\uff09 \u589e\u5927 -XX:G1ReservePercent=n \u8fd9\u4e2a\u503c\u7684\u5927\u5c0f\uff0c\u9ed8\u8ba4\u662f 10.<\/p>\n<p>2\uff09G1 \u901a\u8fc7\u5c1d\u8bd5\u4fdd\u7559\u7a7a\u95f2\u7684\u9884\u7559\u5185\u5b58\u6765\u521b\u5efa\u4e00\u4e2a\u5047\u5929\u82b1\u677f\uff0c\u4ee5\u9632\u9700\u8981\u66f4\u591a\u7684\u201cto-space\u201d\u3002<\/p>\n<ul>\n<li>\u5c3d\u65e9\u5f00\u59cb\u6807\u8bb0\u5468\u671f\u3002<\/li>\n<li>\u52a0\u5927\u5e76\u53d1\u7ebf\u7a0b\u6570\uff0c\u53c2\u6570\uff1a-XX:ConcGCThreads=n<\/li>\n<\/ul>\n<h3>4.5 \u5b8c\u6574 G1 \u53c2\u6570\u5217\u8868<\/h3>\n<p>| \u9009\u9879\u548c\u9ed8\u8ba4\u503c | \u63cf\u8ff0 |<br \/>| &#8212;&#8211; | &#8212;&#8211; |  <br \/>| -XX:+UseG1GC | \u4f7f\u7528 G1 \u5783\u573e\u56de\u6536\u5668 |<br \/>| -XX:MaxGCPauseMillis=n | \u76ee\u6807\u505c\u987f\u65f6\u95f4 \u8fd9\u662f\u4e2a\u8f6f\u76ee\u6807\uff0cJVM \u4f1a\u5c3d\u53ef\u80fd\u6ee1\u8db3\u5b83  |<br \/>| -XX:InitiatingHeapOccupancyPercent=n | \u5806\u4f7f\u7528\u6bd4\u7387\uff0c\u8d85\u8fc7\u8fd9\u4e2a\u6bd4\u7387\u4f1a\u89e6\u53d1 G1 GC\u3002GC \u4f7f\u7528\u6574\u4e2a\u5806\u7684\u4f7f\u7528\u6bd4\u7387\uff0c\u800c\u4e0d\u662f\u67d0\u4e2a\u533a\u57df\u7684\u6bd4\u7387\u3002\u503c\u4e3a 0 \u8868\u793a\u8fdb\u884c\u6052\u5b9a GC \u5faa\u73af\u3002\u9ed8\u8ba4\u662f 45  |<br \/>| -XX:NewRatio=n | \u5e74\u8f7b\u4ee3\/\u8001\u5e74\u4ee3\u7a7a\u95f4\u6bd4\u7387\u3002\u9ed8\u8ba4\u662f 2 |<br \/>| -XX:SurvivorRatio=n | eden\/survivor\u533a\u57df\u7a7a\u95f4\u6bd4\u4f8b\u3002\u9ed8\u8ba4\u662f 8 |<br \/>| -XX:MaxTenuringThreshold=n | \u4fdd\u7559\u671f\u5e74\u9f84\u9608\u503c\uff08\u8d85\u8fc7\u9608\u503c\uff0c\u63d0\u5347\u5230\u8001\u5e74\u4ee3\uff09\u3002\u9ed8\u8ba4 15 |<br \/>| -XX:ParallelGCThreads=n | \u5783\u573e\u56de\u6536\u8fc7\u7a0b\u4e2d\u5e76\u53d1\u7ebf\u7a0b\u6570\u3002\u9ed8\u8ba4\u503c\u968f\u7740\u4f7f\u7528 JVM \u5e73\u53f0\u7684\u4e0d\u540c\u800c\u53d8\u5316\u3002 |<br \/>| -XX:ConcGCThreads=n | \u5e76\u53d1\u5783\u573e\u56de\u6536\u4f7f\u7528\u7684\u7ebf\u7a0b\u6570\u3002\u9ed8\u8ba4\u503c\u968f\u7740\u4f7f\u7528 JVM \u5e73\u53f0\u7684\u4e0d\u540c\u800c\u53d8\u5316 |<br \/>| -XX:G1ReservePercent=n | \u51cf\u5c11\u63d0\u5347\u5931\u8d25\u6bd4\u7387\u800c\u8bbe\u7f6e\u7684\u5047\u5929\u82b1\u677f\u7684\u5806\u7684\u5927\u5c0f\u3002\u9ed8\u8ba4\u503c\u662f 10  |<br \/>| -XX:G1HeapRegionSize=n | \u5728G1\u4e2d\uff0cJava\u5806\u88ab\u7ec6\u5206\u4e3a\u5927\u5c0f\u4e00\u81f4\u7684\u533a\u57df \u8fd9\u5c06\u8bbe\u7f6e\u5404\u4e2a\u5b50\u533a\u57df\u7684\u5927\u5c0f \u8be5\u53c2\u6570\u7684\u9ed8\u8ba4\u503c\u662f\u6839\u636e\u5806\u5927\u5c0f\u786e\u5b9a\u7684 \u6700\u5c0f\u503c\u4e3a 1Mb\uff0c\u6700\u5927\u503c\u4e3a 32Mb  |<\/p>\n<p>\u539f\u6587\uff1a<a href=\"https:\/\/link.segmentfault.com\/?enc=2a%2BvYfNgVzaStZWhVqt6Pw%3D%3D.g%2FKqEUFIASRrpxlCmbbRoNP2%2BLCKMSziKTv2sxPp8WasUtS5%2BKGva4%2FspFkZYKRQ6Y1Hyut54ljuhQ69GaZg7hBW8rernnTouvp4mcWWRDc%3D\" rel=\"nofollow\">https:\/\/www.oracle.com\/techne&#8230;<\/a><\/p>\n<p><a href=\"https:\/\/link.segmentfault.com\/?enc=sjfJeECnrJ2o4%2Fh7O19FgQ%3D%3D.pFCoJIPzSAlBJCWK%2BYgtG3AgF%2FR0MXX61W73zxFomEFW6KAuhcknAKKazhoMkmddIe%2FHm8LUFJhQcFGgHE%2BatG50gKSDZHSeU4OcnqXcNBgz0RhqTO7QFDjpSbFyrdYGC4%2BQ4%2F%2FeyeWpG35xOVN2R86HqqeDJuom7tMYN3W2o1j9KJPhad1WtdHcRbtFkyya\" rel=\"nofollow\">https:\/\/docs.oracle.com\/en\/ja&#8230;<\/a><\/p>\n<p><a href=\"https:\/\/segmentfault.com\/a\/1190000042722821\">https:\/\/segmentfault.com\/a\/1190000042722821<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>1 G1 \u5783\u573e\u56de\u6536\u5668 garbage-first (G1)\u6536\u96c6\u5668\u662f\u4e00\u4e2a\u670d\u52a1\u5668\u98ce\u683c\u7684\u5783\u573e\u6536\u96c6\u5668\uff0c\u9488\u5bf9\u5177\u6709\u5927\u5185\u5b58\u7684 [&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-10006785","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\/10006785","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=10006785"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10006785\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10006785"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10006785"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10006785"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}