{"id":10006156,"date":"2022-08-10T10:04:42","date_gmt":"2022-08-10T02:04:42","guid":{"rendered":"https:\/\/ityet.com\/?p=10006156"},"modified":"2022-08-10T10:04:42","modified_gmt":"2022-08-10T02:04:42","slug":"%e8%b4%9f%e8%bd%bd%e5%9d%87%e8%a1%a1%e5%8e%9f%e7%90%86%e5%88%86%e6%9e%90%e4%b8%8e%e6%ba%90%e7%a0%81%e8%a7%a3%e8%af%bb","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10006156","title":{"rendered":"\u8d1f\u8f7d\u5747\u8861\u539f\u7406\u5206\u6790\u4e0e\u6e90\u7801\u89e3\u8bfb"},"content":{"rendered":"<p>\u4e0a\u4e00\u7bc7\u6587\u7ae0\u4e00\u8d77\u5b66\u4e60\u4e86Resolver\u7684\u539f\u7406\u548c\u6e90\u7801\u5206\u6790\uff0c\u672c\u7bc7\u7ee7\u7eed\u548c\u5927\u5bb6\u4e00\u8d77\u5b66\u4e60\u4e0b\u548cResolver\u5173\u7cfb\u5bc6\u5207\u7684Balancer\u7684\u76f8\u5173\u5185\u5bb9\u3002\u8fd9\u91cc\u8bf4\u7684\u8d1f\u8f7d\u5747\u8861\u4e3b\u8981\u6307\u6570\u636e\u4e2d\u5fc3\u5185\u7684\u8d1f\u8f7d\u5747\u8861\uff0c\u5373RPC\u95f4\u7684\u8d1f\u8f7d\u5747\u8861\u3002<\/p>\n<p>\u4f20\u9001\u95e8 <a href=\"https:\/\/link.segmentfault.com\/?enc=JP8939a5UHNjem21qsY%2F%2Bg%3D%3D.ZWpIRFIjAYdewHtljTBc1oR41Zu%2FEZE1n9sWwBdFLLLq4tMhhdWd8bGCOqB7VulvRIy5mEYdIs9LDhuo5UGhPQ%3D%3D\" rel=\"nofollow\">\u670d\u52a1\u53d1\u73b0\u539f\u7406\u5206\u6790\u4e0e\u6e90\u7801\u89e3\u8bfb<\/a><\/p>\n<p>\u57fa\u4e8e<a href=\"https:\/\/link.segmentfault.com\/?enc=WeBbSH1JhrZUoR6%2FVQquxQ%3D%3D.1D3b20A9dm4MDYr9%2FQjWXtZbyJX%2BLfaP9CgLhoirYdSPginb27KiWWH48AQwbKRkkM%2Fh8FieVMwtpg3hivuuyg%3D%3D\" rel=\"nofollow\">go-zero v1.3.5<\/a> \u548c <a href=\"https:\/\/link.segmentfault.com\/?enc=DXq6KBK42vvWqG1RdFh2cw%3D%3D.rgct114a35LcBVFBd4nMcub9Wp9Jkq7NnjHNJFo85xccgXQ9RknN8a67DJjttklS\" rel=\"nofollow\">grpc-go v1.47.0<\/a><\/p>\n<h2>\u8d1f\u8f7d\u5747\u8861<\/h2>\n<p>\u6bcf\u4e00\u4e2a\u88ab\u8c03\u7528\u670d\u52a1\u90fd\u4f1a\u6709\u591a\u4e2a\u5b9e\u4f8b\uff0c\u90a3\u4e48\u670d\u52a1\u7684\u8c03\u7528\u65b9\u5e94\u8be5\u5c06\u8bf7\u6c42\uff0c\u53d1\u5411\u88ab\u8c03\u7528\u670d\u52a1\u7684\u54ea\u4e00\u4e2a\u670d\u52a1\u5b9e\u4f8b\uff0c\u8fd9\u5c31\u662f\u8d1f\u8f7d\u5747\u8861\u7684\u4e1a\u52a1\u573a\u666f\u3002<\/p>\n<p>\u8d1f\u8f7d\u5747\u8861\u7684\u7b2c\u4e00\u4e2a\u5173\u952e\u70b9\u662f\u516c\u5e73\u6027\uff0c\u5373\u8d1f\u8f7d\u5747\u8861\u9700\u8981\u5173\u6ce8\u88ab\u8c03\u7528\u670d\u52a1\u5b9e\u4f8b\u7ec4\u4e4b\u95f4\u7684\u516c\u5e73\u6027\uff0c\u4e0d\u8981\u51fa\u73b0\u65f1\u7684\u65f1\u6b7b\uff0c\u6d9d\u7684\u6d9d\u6b7b\u7684\u60c5\u51b5\u3002<\/p>\n<p>\u8d1f\u8f7d\u5747\u8861\u7684\u7b2c\u4e8c\u4e2a\u5173\u952e\u70b9\u662f\u6b63\u786e\u6027\uff0c\u5373\u5bf9\u4e8e\u6709\u72b6\u6001\u7684\u670d\u52a1\u6765\u8bf4\uff0c\u8d1f\u8f7d\u5747\u8861\u9700\u8981\u5173\u5fc3\u8bf7\u6c42\u7684\u72b6\u6001\uff0c\u5c06\u8bf7\u6c42\u8c03\u5ea6\u5230\u80fd\u5904\u7406\u5b83\u7684\u540e\u7aef\u5b9e\u4f8b\u4e0a\uff0c\u4e0d\u8981\u51fa\u73b0\u4e0d\u80fd\u5904\u7406\u548c\u9519\u8bef\u5904\u7406\u7684\u60c5\u51b5\u3002<\/p>\n<h3>\u65e0\u72b6\u6001\u7684\u8d1f\u8f7d\u5747\u8861<\/h3>\n<p>\u65e0\u72b6\u6001\u7684\u8d1f\u8f7d\u5747\u8861\u662f\u6211\u4eec\u65e5\u5e38\u5de5\u4f5c\u4e2d\u63a5\u89e6\u6bd4\u8f83\u591a\u7684\u8d1f\u8f7d\u5747\u8861\u6a21\u578b\uff0c\u5b83\u6307\u7684\u662f\u53c2\u4e0e\u8d1f\u8f7d\u5747\u8861\u7684\u540e\u7aef\u5b9e\u4f8b\u662f\u65e0\u72b6\u6001\u7684\uff0c\u6240\u6709\u7684\u540e\u7aef\u5b9e\u4f8b\u90fd\u662f\u5bf9\u7b49\u7684\uff0c\u4e00\u4e2a\u8bf7\u6c42\u4e0d\u8bba\u53d1\u5411\u54ea\u4e00\u4e2a\u5b9e\u4f8b\uff0c\u90fd\u4f1a\u5f97\u5230\u76f8\u540c\u7684\u5e76\u4e14\u6b63\u786e\u7684\u5904\u7406\u7ed3\u679c\uff0c\u6240\u4ee5\u65e0\u72b6\u6001\u7684\u8d1f\u8f7d\u5747\u8861\u7b56\u7565\u4e0d\u9700\u8981\u5173\u5fc3\u8bf7\u6c42\u7684\u72b6\u6001\u3002\u4e0b\u9762\u4ecb\u7ecd\u4e24\u79cd\u65e0\u72b6\u6001\u8d1f\u8f7d\u5747\u8861\u7b97\u6cd5\u3002<\/p>\n<h4>\u8f6e\u8be2<\/h4>\n<p>\u8f6e\u8be2\u7684\u8d1f\u8f7d\u5747\u8861\u7b56\u7565\u975e\u5e38\u7b80\u5355\uff0c\u53ea\u9700\u8981\u5c06\u8bf7\u6c42\u6309\u987a\u5e8f\u5206\u914d\u7ed9\u591a\u4e2a\u5b9e\u4f8b\uff0c\u4e0d\u7528\u518d\u505a\u5176\u4ed6\u7684\u5904\u7406\u3002\u4f8b\u5982\uff0c\u8f6e\u8be2\u7b56\u7565\u4f1a\u5c06\u7b2c\u4e00\u4e2a\u8bf7\u6c42\u5206\u914d\u7ed9\u7b2c\u4e00\u4e2a\u5b9e\u4f8b\uff0c\u7136\u540e\u5c06\u4e0b\u4e00\u4e2a\u8bf7\u6c42\u5206\u914d\u7ed9\u7b2c\u4e8c\u4e2a\u5b9e\u4f8b\uff0c\u8fd9\u6837\u4f9d\u6b21\u5206\u914d\u4e0b\u53bb\uff0c\u5206\u914d\u5b8c\u4e00\u8f6e\u4e4b\u540e\uff0c\u518d\u56de\u5230\u5f00\u5934\u5206\u914d\u7ed9\u7b2c\u4e00\u4e2a\u5b9e\u4f8b\uff0c\u518d\u4f9d\u6b21\u5206\u914d\u3002\u8f6e\u8be2\u5728\u8def\u7531\u65f6\uff0c\u4e0d\u5229\u7528\u8bf7\u6c42\u7684\u72b6\u6001\u4fe1\u606f\uff0c\u5c5e\u4e8e\u65e0\u72b6\u6001\u7684\u8d1f\u8f7d\u5747\u8861\u7b56\u7565\uff0c\u6240\u4ee5\u5b83\u4e0d\u80fd\u7528\u4e8e\u6709\u72b6\u6001\u5b9e\u4f8b\u7684\u8d1f\u8f7d\u5747\u8861\u5668\uff0c\u5426\u5219\u6b63\u786e\u6027\u4f1a\u51fa\u73b0\u95ee\u9898\u3002\u5728\u516c\u5e73\u6027\u65b9\u9762\uff0c\u56e0\u4e3a\u8f6e\u8be2\u7b56\u7565\u53ea\u662f\u6309\u987a\u5e8f\u5206\u914d\u8bf7\u6c42\uff0c\u6240\u4ee5\u9002\u7528\u4e8e\u8bf7\u6c42\u7684\u5de5\u4f5c\u8d1f\u8f7d\u548c\u5b9e\u4f8b\u7684\u5904\u7406\u80fd\u529b\u5dee\u5f02\u90fd\u8f83\u5c0f\u7684\u60c5\u51b5\u3002<\/p>\n<h4>\u6743\u91cd\u8f6e\u8be2<\/h4>\n<p>\u6743\u91cd\u8f6e\u8be2\u7684\u8d1f\u8f7d\u5747\u8861\u7b56\u7565\u662f\u5c06\u6bcf\u4e00\u4e2a\u540e\u7aef\u5b9e\u4f8b\u5206\u914d\u4e00\u4e2a\u6743\u91cd\uff0c\u5206\u914d\u8bf7\u6c42\u7684\u6570\u91cf\u548c\u5b9e\u4f8b\u7684\u6743\u91cd\u6210\u6b63\u6bd4\u8f6e\u8be2\u3002\u4f8b\u5982\u6709\u4e24\u4e2a\u5b9e\u4f8b A\uff0cB\uff0c\u5047\u8bbe\u6211\u4eec\u8bbe\u7f6e A \u7684\u6743\u91cd\u4e3a 20\uff0cB \u7684\u6743\u91cd\u4e3a 80\uff0c\u90a3\u4e48\u8d1f\u8f7d\u5747\u8861\u4f1a\u5c06 20% \u7684\u8bf7\u6c42\u6570\u91cf\u5206\u914d\u7ed9 A\uff0c80 % \u7684\u8bf7\u6c42\u6570\u91cf\u5206\u914d\u7ed9 B\u3002\u6743\u91cd\u8f6e\u8be2\u5728\u8def\u7531\u65f6\uff0c\u4e0d\u5229\u7528\u8bf7\u6c42\u7684\u72b6\u6001\u4fe1\u606f\uff0c\u5c5e\u4e8e\u65e0\u72b6\u6001\u7684\u8d1f\u8f7d\u5747\u8861\u7b56\u7565\uff0c\u6240\u4ee5\u5b83\u4e5f\u4e0d\u80fd\u7528\u4e8e\u6709\u72b6\u6001\u5b9e\u4f8b\u7684\u8d1f\u8f7d\u5747\u8861\u5668\uff0c\u5426\u5219\u6b63\u786e\u6027\u4f1a\u51fa\u73b0\u95ee\u9898\u3002\u5728\u516c\u5e73\u6027\u65b9\u9762\uff0c\u56e0\u4e3a\u6743\u91cd\u7b56\u7565\u4f1a\u6309\u5b9e\u4f8b\u7684\u6743\u91cd\u6bd4\u4f8b\u6765\u5206\u914d\u8bf7\u6c42\u6570\uff0c\u6240\u4ee5\uff0c\u6211\u4eec\u53ef\u4ee5\u5229\u7528\u5b83\u89e3\u51b3\u5b9e\u4f8b\u7684\u5904\u7406\u80fd\u529b\u5dee\u5f02\u7684\u95ee\u9898\uff0c\u8ba4\u4e3a\u5b83\u7684\u516c\u5e73\u6027\u6bd4\u8f6e\u8be2\u7b56\u7565\u8981\u597d\u3002<\/p>\n<h3>\u6709\u72b6\u6001\u8d1f\u8f7d\u5747\u8861<\/h3>\n<p>\u6709\u72b6\u6001\u8d1f\u8f7d\u5747\u8861\u662f\u6307\uff0c\u5728\u8d1f\u8f7d\u5747\u8861\u7b56\u7565\u4e2d\u4f1a\u4fdd\u5b58\u670d\u52a1\u7aef\u7684\u4e00\u4e9b\u72b6\u6001\uff0c\u7136\u540e\u6839\u636e\u8fd9\u4e9b\u72b6\u6001\u6309\u7167\u4e00\u5b9a\u7684\u7b97\u6cd5\u9009\u62e9\u51fa\u5bf9\u5e94\u7684\u5b9e\u4f8b\u3002<\/p>\n<h4>P2C+EWMA<\/h4>\n<p>\u5728go-zero\u4e2d\u9ed8\u8ba4\u4f7f\u7528\u7684\u662fP2C\u7684\u8d1f\u8f7d\u5747\u8861\u7b97\u6cd5\u3002\u8be5\u7b97\u6cd5\u7684\u539f\u7406\u6bd4\u8f83\u7b80\u5355\uff0c\u5373\u968f\u673a\u4ece\u6240\u6709\u53ef\u7528\u8282\u70b9\u4e2d\u9009\u62e9\u4e24\u4e2a\u8282\u70b9\uff0c\u7136\u540e\u8ba1\u7b97\u8fd9\u4e24\u4e2a\u8282\u70b9\u7684\u8d1f\u8f7d\u60c5\u51b5\uff0c\u9009\u62e9\u8d1f\u8f7d\u8f83\u4f4e\u7684\u4e00\u4e2a\u8282\u70b9\u6765\u670d\u52a1\u672c\u6b21\u8bf7\u6c42\u3002\u4e3a\u4e86\u907f\u514d\u67d0\u4e9b\u8282\u70b9\u4e00\u76f4\u5f97\u4e0d\u5230\u9009\u62e9\u5bfc\u81f4\u4e0d\u5e73\u8861\uff0c\u4f1a\u5728\u8d85\u8fc7\u4e00\u5b9a\u7684\u65f6\u95f4\u540e\u5f3a\u5236\u9009\u62e9\u4e00\u6b21\u3002<\/p>\n<p>\u5728\u8be5\u590d\u6742\u5747\u8861\u7b97\u6cd5\u4e2d\uff0c\u591a\u51fa\u91c7\u7528\u4e86EWMA\u6307\u6570\u79fb\u52a8\u52a0\u6743\u5e73\u5747\u7684\u7b97\u6cd5\uff0c\u8868\u793a\u662f\u4e00\u6bb5\u65f6\u95f4\u5185\u7684\u5747\u503c\u3002\u8be5\u7b97\u6cd5\u76f8\u5bf9\u4e8e\u7b97\u6570\u5e73\u5747\u6765\u8bf4\u5bf9\u4e8e\u7a81\u7136\u7684\u7f51\u7edc\u6296\u52a8\u6ca1\u6709\u90a3\u4e48\u654f\u611f\uff0c\u7a81\u7136\u7684\u6296\u52a8\u4e0d\u4f1a\u4f53\u73b0\u5728\u8bf7\u6c42\u7684lag\u4e2d\uff0c\u4ece\u800c\u53ef\u4ee5\u8ba9\u7b97\u6cd5\u66f4\u52a0\u5747\u8861\u3002<\/p>\n<p><strong>go-zero\/zrpc\/internal\/balancer\/p2c\/p2c.go:133<\/strong><\/p>\n<pre><code class=\"go\">atomic.StoreUint64(&amp;c.lag, uint64(float64(olag)*w+float64(lag)*(1-w)))<\/code><\/pre>\n<p><strong>go-zero\/zrpc\/internal\/balancer\/p2c\/p2c.go:139<\/strong><\/p>\n<pre><code class=\"go\">atomic.StoreUint64(&amp;c.success, uint64(float64(osucc)*w+float64(success)*(1-w)))<\/code><\/pre>\n<p>\u7cfb\u6570w\u662f\u4e00\u4e2a\u65f6\u95f4\u8870\u51cf\u503c\uff0c\u5373\u4e24\u6b21\u8bf7\u6c42\u7684\u95f4\u9694\u8d8a\u5927\uff0c\u5219\u7cfb\u6570w\u5c31\u8d8a\u5c0f\u3002<\/p>\n<p><strong>go-zero\/zrpc\/internal\/balancer\/p2c\/p2c.go:124<\/strong><\/p>\n<pre><code class=\"go\">w := math.Exp(float64(-td) \/ float64(decayTime))<\/code><\/pre>\n<p>\u8282\u70b9\u7684load\u503c\u662f\u901a\u8fc7\u8be5\u8fde\u63a5\u7684\u8bf7\u6c42\u5ef6\u8fdf <strong>lag<\/strong> \u548c\u5f53\u524d\u8bf7\u6c42\u6570 <strong>inflight<\/strong> \u7684\u4e58\u79ef\u6240\u5f97\uff0c\u5982\u679c\u8bf7\u6c42\u7684\u5ef6\u8fdf\u8d8a\u5927\u6216\u8005\u5f53\u524d\u6b63\u5728\u5904\u7406\u7684\u8bf7\u6c42\u6570\u8d8a\u591a\u8868\u660e\u8be5\u8282\u70b9\u7684\u8d1f\u8f7d\u8d8a\u9ad8\u3002<\/p>\n<p><strong>go-zero\/zrpc\/internal\/balancer\/p2c\/p2c.go:199<\/strong><\/p>\n<pre><code class=\"go\">func (c *subConn) load() int64 {\n  \/\/ plus one to avoid multiply zero\n  lag := int64(math.Sqrt(float64(atomic.LoadUint64(&amp;c.lag) + 1)))\n  load := lag * (atomic.LoadInt64(&amp;c.inflight) + 1)\n  if load == 0 {\n    return penalty\n  }\n\n  return load\n}<\/code><\/pre>\n<h2>\u6e90\u7801\u5206\u6790<\/h2>\n<blockquote><p>\u5982\u4e0b\u6e90\u7801\u4f1a\u6d89\u53cago-zero\u548cgRPC\uff0c\u8bf7\u6839\u636e\u7ed9\u51fa\u7684\u4ee3\u7801\u8def\u5f84\u8fdb\u884c\u533a\u5206<\/p><\/blockquote>\n<p>\u5728gRPC\u4e2d\uff0cBalancer\u548cResolver\u4e00\u6837\u4e5f\u53ef\u4ee5\u81ea\u5b9a\u4e49\uff0c\u540c\u6837\u4e5f\u662f\u901a\u8fc7Register\u65b9\u6cd5\u8fdb\u884c\u6ce8\u518c<\/p>\n<p><strong>grpc-go\/balancer\/balancer.go:53<\/strong><\/p>\n<pre><code class=\"go\">func Register(b Builder) {\n  m[strings.ToLower(b.Name())] = b\n}<\/code><\/pre>\n<p>Register\u7684\u53c2\u6570Builder\u4e3a\u63a5\u53e3\uff0c\u5728Builder\u63a5\u53e3\u4e2d\uff0cBuild\u65b9\u6cd5\u7684\u7b2c\u4e00\u4e2a\u53c2\u6570ClientConn\u4e5f\u4e3a\u63a5\u53e3\uff0cBuild\u65b9\u6cd5\u7684\u8fd4\u56de\u503cBalancer\u540c\u6837\u4e5f\u662f\u63a5\u53e3\uff0c\u5b9a\u4e49\u5982\u4e0b\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042295404\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u53ef\u4ee5\u770b\u51fa\uff0c\u8981\u60f3\u5b9e\u73b0\u81ea\u5b9a\u4e49\u7684Balancer\u7684\u8bdd\uff0c\u5c31\u5fc5\u987b\u8981\u5b9e\u73b0balancer.Builder\u63a5\u53e3\u3002<\/p>\n<p>\u5728\u4e86\u89e3\u4e86gRPC\u63d0\u4f9b\u7684Balancer\u7684\u6ce8\u518c\u65b9\u5f0f\u4e4b\u540e\uff0c\u6211\u4eec\u770b\u4e00\u4e0bgo-zero\u662f\u5728\u4ec0\u4e48\u5730\u65b9\u8fdb\u884cBalancer\u6ce8\u518c\u7684<\/p>\n<p><strong>go-zero\/zrpc\/internal\/balancer\/p2c\/p2c.go:36<\/strong><\/p>\n<pre><code class=\"go\">func init() {\n  balancer.Register(newBuilder())\n}<\/code><\/pre>\n<p>\u5728go-zero\u4e2d\u5e76\u6ca1\u6709\u5b9e\u73b0 <strong>balancer.Builder<\/strong> \u63a5\u53e3\uff0c\u800c\u662f\u4f7f\u7528gRPC\u63d0\u4f9b\u7684 <strong>base.baseBuilder<\/strong> \u8fdb\u884c\u6ce8\u518c\uff0c<strong>base.baseBuilder<\/strong> \u5b9e\u73b0\u4e86<strong>balancer.Builder<\/strong> \u63a5\u53e3\u3002\u521b\u5efabaseBuilder\u7684\u65f6\u5019\u8c03\u7528\u4e86 <strong>base.NewBalancerBuilder<\/strong> \u65b9\u6cd5\uff0c\u9700\u8981\u4f20\u5165 <strong>PickerBuilder<\/strong> \u53c2\u6570\uff0cPickerBuilder\u4e3a\u63a5\u53e3\uff0c\u5728go-zero\u4e2d <strong>p2c.p2cPickerBuilder<\/strong> \u5b9e\u73b0\u4e86\u8be5\u63a5\u53e3\u3002<\/p>\n<p>PickerBuilder\u63a5\u53e3Build\u65b9\u6cd5\u8fd4\u56de\u503c <strong>balancer.Picker<\/strong> \u4e5f\u662f\u4e00\u4e2a\u63a5\u53e3\uff0c<strong>p2c.p2cPicker<\/strong> \u5b9e\u73b0\u4e86\u8be5\u63a5\u53e3\u3002<\/p>\n<p><strong>grpc-go\/balancer\/base\/base.go:65<\/strong><\/p>\n<pre><code class=\"go\">func NewBalancerBuilder(name string, pb PickerBuilder, config Config) balancer.Builder {\n  return &amp;baseBuilder{\n    name:          name,\n    pickerBuilder: pb,\n    config:        config,\n  }\n}<\/code><\/pre>\n<p>\u5404\u7ed3\u6784\u4e4b\u95f4\u7684\u5173\u7cfb\u5982\u4e0b\u56fe\u6240\u793a\uff0c\u5176\u4e2d\u5404\u7ed3\u6784\u6a21\u5757\u5bf9\u5e94\u7684\u5305\u4e3a\uff1a<\/p>\n<ul>\n<li>balancer\uff1agrpc-go\/balancer<\/li>\n<li>base\uff1agrpc-go\/balancer\/base<\/li>\n<li>p2c: go-zero\/zrpc\/internal\/balancer\/p2c<\/li>\n<\/ul>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042295405\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<h3>\u5728\u54ea\u91cc\u83b7\u53d6\u5df2\u6ce8\u518c\u7684Balancer\uff1f<\/h3>\n<p>\u901a\u8fc7\u4e0a\u9762\u7684\u6d41\u7a0b\u6b65\u9aa4\uff0c\u5df2\u7ecf\u77e5\u9053\u4e86\u5982\u4f55\u81ea\u5b9a\u4e49Balancer\uff0c\u4ee5\u53ca\u5982\u4f55\u6ce8\u518c\u81ea\u5b9a\u4e49\u7684Blancer\u3002\u65e2\u7136\u6ce8\u518c\u4e86\u80af\u5b9a\u5c31\u4f1a\u83b7\u53d6\uff0c\u63a5\u4e0b\u6765\u770b\u4e00\u4e0b\u662f\u5728\u54ea\u91cc\u83b7\u53d6\u5df2\u7ecf\u6ce8\u518c\u7684Balancer\u7684\u3002<\/p>\n<p>\u6211\u4eec\u77e5\u9053Resolver\u662f\u901a\u8fc7\u89e3\u6790DialContext\u7684\u7b2c\u4e8c\u4e2a\u53c2\u6570target\uff0c\u4ece\u800c\u5f97\u5230Resolver\u7684name\uff0c\u7136\u540e\u6839\u636ename\u83b7\u53d6\u5230\u5bf9\u5e94\u7684Resolver\u7684\u3002\u83b7\u53d6Balancer\u540c\u6837\u4e5f\u662f\u6839\u636e\u540d\u79f0\uff0cBalancer\u7684\u540d\u79f0\u662f\u5728\u521b\u5efagRPC Client\u7684\u65f6\u5019\u901a\u8fc7\u914d\u7f6e\u9879\u4f20\u5165\u7684\uff0c\u8fd9\u91cc\u7684p2c.Name\u4e3a\u6ce8\u518cBalancer\u65f6\u6307\u5b9a\u7684\u540d\u79f0 p2c_ewma \uff0c\u5982\u4e0b\uff1a<\/p>\n<p><strong>go-zero\/zrpc\/internal\/client.go:50<\/strong><\/p>\n<pre><code class=\"go\">func NewClient(target string, opts ...ClientOption) (Client, error) {\n  var cli client\n\n  svcCfg := fmt.Sprintf(`{&quot;loadBalancingPolicy&quot;:&quot;%s&quot;}`, p2c.Name)\n  balancerOpt := WithDialOption(grpc.WithDefaultServiceConfig(svcCfg))\n  opts = append([]ClientOption{balancerOpt}, opts...)\n  if err := cli.dial(target, opts...); err != nil {\n    return nil, err\n  }\n\n  return &amp;cli, nil\n}<\/code><\/pre>\n<p>\u5728\u4e0a\u4e00\u7bc7\u6587\u7ae0\u4e2d\uff0c\u6211\u4eec\u5df2\u7ecf\u77e5\u9053\u5f53\u521b\u5efagRPC\u5ba2\u6237\u7aef\u7684\u65f6\u5019\uff0c\u4f1a\u89e6\u53d1\u8c03\u7528\u81ea\u5b9a\u4e49Resolver\u7684Build\u65b9\u6cd5\uff0c\u5728Build\u65b9\u6cd5\u5185\u90e8\u83b7\u53d6\u5230\u670d\u52a1\u5730\u5740\u5217\u8868\u540e\uff0c\u901a\u8fc7cc.UpdateState\u65b9\u6cd5\u8fdb\u884c\u72b6\u6001\u66f4\u65b0\uff0c\u540e\u9762\u5f53\u76d1\u542c\u5230\u670d\u52a1\u72b6\u6001\u53d8\u5316\u7684\u65f6\u5019\u540c\u6837\u4e5f\u4f1a\u8c03\u7528cc.UpdateState\u8fdb\u884c\u72b6\u6001\u7684\u66f4\u65b0\uff0c\u800c\u8fd9\u91cc\u7684cc\u6307\u7684\u5c31\u662f <strong>ccResolverWrapper<\/strong> \u5bf9\u8c61\uff0c\u8fd9\u4e00\u90e8\u5206\u5982\u679c\u5fd8\u8bb0\u7684\u8bdd\uff0c\u53ef\u4ee5\u518d\u53bb\u56de\u987e\u4e00\u4e0b\u8bb2\u89e3Resolver\u7684\u90a3\u7bc7\u6587\u7ae0\uff0c\u4ee5\u4fbf\u80fd\u4e1d\u6ed1\u63a5\u5165\u672c\u7bc7\uff1a<\/p>\n<p><strong>go-zero\/zrpc\/resolver\/internal\/kubebuilder.go:51<\/strong><\/p>\n<pre><code class=\"go\">if err := cc.UpdateState(resolver.State{\n  Addresses: addrs,\n}); err != nil {\n  logx.Error(err)\n}<\/code><\/pre>\n<p>\u8fd9\u91cc\u6709\u51e0\u4e2a\u91cd\u8981\u7684\u6a21\u5757\u5bf9\u8c61\uff0c\u5982\u4e0b\uff1a<\/p>\n<ul>\n<li>ClientConn\uff1agrpc-go\/clientconn.go:464<\/li>\n<li>ccResolverWrapper\uff1agrpc-go\/resolver_conn_wrapper.go:36<\/li>\n<li>ccBalancerWrapper\uff1agrpc-go\/balancer_conn_wrappers.go:48<\/li>\n<li>Balancer\uff1agrpc-go\/internal\/balancer\/gracefulswitch\/gracefulswitch.go:46<\/li>\n<li>balancerWrapper\uff1agrpc-go\/internal\/balancer\/gracefulswitch\/gracefulswitch.go:247<\/li>\n<\/ul>\n<p>\u5f53\u76d1\u542c\u5230\u670d\u52a1\u72b6\u6001\u7684\u53d8\u66f4\u540e\uff08\u9996\u6b21\u542f\u52a8\u6216\u8005\u901a\u8fc7Watch\u76d1\u542c\u53d8\u5316\uff09\u8c03\u7528 <strong>ccResolverWrapper.UpdateState<\/strong> \u89e6\u53d1\u66f4\u65b0\u72b6\u6001\u7684\u6d41\u7a0b\uff0c\u5404\u6a21\u5757\u95f4\u7684\u8c03\u7528\u94fe\u8def\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042295406\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u83b7\u53d6Balancer\u7684\u52a8\u4f5c\u662f\u5728 <strong>ccBalancerWrapper.handleSwitchTo<\/strong> \u65b9\u6cd5\u4e2d\u89e6\u53d1\u7684\uff0c\u4ee3\u7801\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<p><strong>grpc-go\/balancer_conn_wrappers.go:266<\/strong><\/p>\n<pre><code class=\"go\">builder := balancer.Get(name)\nif builder == nil {\n  channelz.Warningf(logger, ccb.cc.channelzID, &quot;Channel switches to new LB policy %q, since the specified LB policy %q was not registered&quot;, PickFirstBalancerName, name)\n  builder = newPickfirstBuilder()\n} else {\n  channelz.Infof(logger, ccb.cc.channelzID, &quot;Channel switches to new LB policy %q&quot;, name)\n}\n\nif err := ccb.balancer.SwitchTo(builder); err != nil {\n  channelz.Errorf(logger, ccb.cc.channelzID, &quot;Channel failed to build new LB policy %q: %v&quot;, name, err)\n  return\n}\nccb.curBalancerName = builder.Name()<\/code><\/pre>\n<p>\u7136\u540e\u5728 <strong>Balancer.SwitchTo<\/strong> \u65b9\u6cd5\u4e2d\uff0c\u8c03\u7528\u4e86\u81ea\u5b9a\u4e49Balancer\u7684Build\u65b9\u6cd5\uff1a<\/p>\n<p><strong>grpc-go\/internal\/balancer\/gracefulswitch\/gracefulswitch.go:121<\/strong><\/p>\n<pre><code class=\"go\">newBalancer := builder.Build(bw, gsb.bOpts)<\/code><\/pre>\n<p>\u4e0a\u6587\u6709\u63d0\u5230Build\u65b9\u6cd5\u7684\u7b2c\u4e00\u4e2a\u53c2\u6570\u4e3a\u63a5\u53e3 <strong>balancer.ClientConn<\/strong> \uff0c\u800c\u8fd9\u91cc\u4f20\u5165\u7684\u4e3a <strong>balancerWrapper<\/strong> \uff0c\u6240\u4ee5gracefulswitch.balancerWrapper\u5b9e\u73b0\u4e86\u8be5\u63a5\u53e3\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042295407\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u5230\u8fd9\u91cc\u6211\u4eec\u5df2\u7ecf\u77e5\u9053\u4e86\u83b7\u53d6\u81ea\u5b9a\u4e49Balancer\u662f\u5728\u54ea\u91cc\u89e6\u8fbe\u7684\uff0c\u4ee5\u53ca\u5728\u54ea\u91cc\u83b7\u53d6\u7684\u81ea\u5b9a\u4e49\u7684Balancer\uff0c\u548cbalancer.Builder\u7684Build\u65b9\u6cd5\u5728\u54ea\u91cc\u88ab\u8c03\u7528\u3002<\/p>\n<p>\u901a\u8fc7\u4e0a\u6587\u53ef\u77e5\u8fd9\u91cc\u7684balancer.Builder\u4e3abaseBuilder\uff0c\u6240\u4ee5\u8c03\u7528\u7684Build\u65b9\u6cd5\u4e3abaseBuilder\u7684Build\u65b9\u6cd5\uff0cBuild\u65b9\u6cd5\u7684\u5b9a\u4e49\u5982\u4e0b\uff1a<\/p>\n<p><strong>grpc-go\/balancer\/base\/balancer.go:39<\/strong><\/p>\n<pre><code class=\"go\">func (bb *baseBuilder) Build(cc balancer.ClientConn, opt balancer.BuildOptions) balancer.Balancer {\n  bal := &amp;baseBalancer{\n    cc:            cc,\n    pickerBuilder: bb.pickerBuilder,\n\n    subConns: resolver.NewAddressMap(),\n    scStates: make(map[balancer.SubConn]connectivity.State),\n    csEvltr:  &amp;balancer.ConnectivityStateEvaluator{},\n    config:   bb.config,\n  }\n  bal.picker = NewErrPicker(balancer.ErrNoSubConnAvailable)\n  return bal\n}<\/code><\/pre>\n<p>Build\u65b9\u6cd5\u8fd4\u56de\u4e86baseBalancer\uff0c\u53ef\u4ee5\u77e5\u9053baseBalancer\u5b9e\u73b0\u4e86balancer.Balancer\u63a5\u53e3\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042295408\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u518d\u6765\u56de\u987e\u4e0b\u8fd9\u4e2a\u6d41\u7a0b\uff0c\u5176\u5b9e\u4e3b\u8981\u505a\u4e86\u5982\u4e0b\u51e0\u4ef6\u4e8b\uff1a<\/p>\n<ol>\n<li>\u5728\u81ea\u5b9a\u4e49\u7684Resolver\u4e2d\u76d1\u542c\u670d\u52a1\u72b6\u6001\u7684\u53d8\u66f4<\/li>\n<li>\u901a\u8fc7UpdateState\u6765\u66f4\u65b0\u72b6\u6001<\/li>\n<li>\u83b7\u53d6\u81ea\u5b9a\u4e49\u7684Balancer<\/li>\n<li>\u6267\u884c\u81ea\u5b9a\u4e49Balancer\u7684Build\u65b9\u6cd5\u83b7\u53d6Balancer<\/li>\n<\/ol>\n<h3>\u5982\u4f55\u521b\u5efa\u8fde\u63a5\uff1f<\/h3>\n<p>\u7ee7\u7eed\u56de\u5230ClientConn\u7684updateResolverState\u65b9\u6cd5\uff0c\u5728\u65b9\u6cd5\u7684\u6700\u540e\u8c03\u7528balancerWrapper.updateClientConnState\u65b9\u6cd5\u66f4\u65b0\u5ba2\u6237\u7aef\u7684\u8fde\u63a5\u72b6\u6001\uff1a<\/p>\n<p><strong>grpc-go\/clientconn.go:664<\/strong><\/p>\n<pre><code class=\"go\">uccsErr := bw.updateClientConnState(&amp;balancer.ClientConnState{ResolverState: s, BalancerConfig: balCfg})\nif ret == nil {\nret = uccsErr \/\/ prefer ErrBadResolver state since any other error is\n\/\/ currently meaningless to the caller.\n}<\/code><\/pre>\n<p>\u540e\u9762\u7684\u8c03\u7528\u94fe\u8def\u5982\u4e0b\u56fe\u6240\u793a\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042295409\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u6700\u7ec8\u4f1a\u8c03\u7528baseBalancer.UpdateClientConnState\u65b9\u6cd5\uff1a<\/p>\n<p><strong>grpc-go\/balancer\/base\/balancer.go:94<\/strong><\/p>\n<pre><code class=\"go\">func (b *baseBalancer) UpdateClientConnState(s balancer.ClientConnState) error {\n  \/\/ .............\n  b.resolverErr = nil\n  addrsSet := resolver.NewAddressMap()\n  for _, a := range s.ResolverState.Addresses {\n    addrsSet.Set(a, nil)\n    if _, ok := b.subConns.Get(a); !ok {\n      sc, err := b.cc.NewSubConn([]resolver.Address{a}, balancer.NewSubConnOptions{HealthCheckEnabled: b.config.HealthCheck})\n      if err != nil {\n        logger.Warningf(&quot;base.baseBalancer: failed to create new SubConn: %v&quot;, err)\n        continue\n      }\n      b.subConns.Set(a, sc)\n      b.scStates[sc] = connectivity.Idle\n      b.csEvltr.RecordTransition(connectivity.Shutdown, connectivity.Idle)\n      sc.Connect()\n    }\n  }\n  for _, a := range b.subConns.Keys() {\n    sci, _ := b.subConns.Get(a)\n    sc := sci.(balancer.SubConn)\n    if _, ok := addrsSet.Get(a); !ok {\n      b.cc.RemoveSubConn(sc)\n      b.subConns.Delete(a)\n    }\n  }\n\n  \/\/ ................\n}<\/code><\/pre>\n<p>\u5f53\u7b2c\u4e00\u6b21\u89e6\u53d1\u8c03\u7528UpdateClientConnState\u7684\u65f6\u5019\uff0c\u5982\u4e0b\u4ee3\u7801\u4e2d ok \u4e3a false\uff1a<\/p>\n<pre><code class=\"go\">_, ok := b.subConns.Get(a);<\/code><\/pre>\n<p>\u6240\u4ee5\u4f1a\u521b\u5efa\u65b0\u7684\u8fde\u63a5\uff1a<\/p>\n<pre><code class=\"go\">sc, err := b.cc.NewSubConn([]resolver.Address{a}, balancer.NewSubConnOptions{HealthCheckEnabled: b.config.HealthCheck})<\/code><\/pre>\n<p>\u8fd9\u91cc\u7684 <strong>b.cc<\/strong> \u5373\u4e3a <strong>balancerWrapper<\/strong>\uff0c\u5fd8\u8bb0\u7684\u76c6\u53cb\u53ef\u4ee5\u5f80\u4e0a\u7ffb\u770b\u590d\u4e60\u4e00\u4e0b\uff0c\u4e5f\u5c31\u662f\u4f1a\u8c03\u7528 balancerWrapper.NewSubConn\u521b\u5efa\u8fde\u63a5<\/p>\n<p><strong>grpc-go\/internal\/balancer\/gracefulswitch\/gracefulswitch.go:328<\/strong><\/p>\n<pre><code class=\"go\">func (bw *balancerWrapper) NewSubConn(addrs []resolver.Address, opts balancer.NewSubConnOptions) (balancer.SubConn, error) {\n  \/\/ .............\n\n  sc, err := bw.gsb.cc.NewSubConn(addrs, opts)\n  if err != nil {\n    return nil, err\n  }\n  \n  \/\/ .............\n  \n  bw.subconns[sc] = true\n  \n  \/\/ .............\n}<\/code><\/pre>\n<p>bw.gsb.cc\u5373\u4e3accBalancerWrapper\uff0c\u6240\u4ee5\u8fd9\u91cc\u4f1a\u8c03\u7528ccBalancerWrapper.NewSubConn\u521b\u5efa\u8fde\u63a5\uff1a<\/p>\n<p><strong>grpc-go\/balancer_conn_wrappers.go:299<\/strong><\/p>\n<pre><code class=\"go\">func (ccb *ccBalancerWrapper) NewSubConn(addrs []resolver.Address, opts balancer.NewSubConnOptions) (balancer.SubConn, error) {\n  if len(addrs) &lt;= 0 {\n    return nil, fmt.Errorf(&quot;grpc: cannot create SubConn with empty address list&quot;)\n  }\n  ac, err := ccb.cc.newAddrConn(addrs, opts)\n  if err != nil {\n    channelz.Warningf(logger, ccb.cc.channelzID, &quot;acBalancerWrapper: NewSubConn: failed to newAddrConn: %v&quot;, err)\n    return nil, err\n  }\n  acbw := &amp;acBalancerWrapper{ac: ac}\n  acbw.ac.mu.Lock()\n  ac.acbw = acbw\n  acbw.ac.mu.Unlock()\n  return acbw, nil\n}<\/code><\/pre>\n<p>\u6700\u7ec8\u8fd4\u56de\u7684\u662facBalancerWrapper\u5bf9\u8c61\uff0cacBalancerWrapper\u5b9e\u73b0\u4e86balancer.SubConn\u63a5\u53e3\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042295410\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u8c03\u7528\u6d41\u7a0b\u56fe\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042295411\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u521b\u5efa\u8fde\u63a5\u7684\u9ed8\u8ba4\u72b6\u6001\u4e3a <strong>connectivity.Idle<\/strong> :<\/p>\n<p><strong>grpc-go\/clientconn.go:699<\/strong><\/p>\n<pre><code class=\"go\">func (cc *ClientConn) newAddrConn(addrs []resolver.Address, opts balancer.NewSubConnOptions) (*addrConn, error) {\n  ac := &amp;addrConn{\n    state:        connectivity.Idle,\n    cc:           cc,\n    addrs:        addrs,\n    scopts:       opts,\n    dopts:        cc.dopts,\n    czData:       new(channelzData),\n    resetBackoff: make(chan struct{}),\n  }\n \n  \/\/ ...........\n}<\/code><\/pre>\n<p>\u5728gRPC\u4e2d\u4e3a\u8fde\u63a5\u5b9a\u4e49\u4e86\u4e94\u79cd\u72b6\u6001\uff0c\u5206\u522b\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"go\">const (\n  \/\/ Idle indicates the ClientConn is idle.\n  Idle State = iota\n  \/\/ Connecting indicates the ClientConn is connecting.\n  Connecting\n  \/\/ Ready indicates the ClientConn is ready for work.\n  Ready\n  \/\/ TransientFailure indicates the ClientConn has seen a failure but expects to recover.\n  TransientFailure\n  \/\/ Shutdown indicates the ClientConn has started shutting down.\n  Shutdown\n)<\/code><\/pre>\n<p>\u5728 <strong>baseBalancer <\/strong> \u4e2d\u901a\u8fc7b.scStates\u4fdd\u5b58\u521b\u5efa\u7684\u8fde\u63a5\uff0c\u521d\u59cb\u72b6\u6001\u4e5f\u4e3aconnectivity.Idle\uff0c\u4e4b\u540e\u901a\u8fc7sc.Connect()\u8fdb\u884c\u8fde\u63a5\uff1a<\/p>\n<p><strong>grpc-go\/balancer\/base\/balancer.go:112<\/strong><\/p>\n<pre><code class=\"go\">b.subConns.Set(a, sc)\nb.scStates[sc] = connectivity.Idle\nb.csEvltr.RecordTransition(connectivity.Shutdown, connectivity.Idle)\nsc.Connect()<\/code><\/pre>\n<p>\u8fd9\u91ccsc.Connetc\u8c03\u7528\u7684\u662facBalancerWrapper\u7684Connect\u65b9\u6cd5\uff0c\u53ef\u4ee5\u770b\u5230\u8fd9\u91cc\u521b\u5efa\u8fde\u63a5\u662f\u5f02\u6b65\u8fdb\u884c\u7684\uff1a<\/p>\n<p><strong>grpc-go\/balancer_conn_wrappers.go:406<\/strong><\/p>\n<pre><code class=\"go\">func (acbw *acBalancerWrapper) Connect() {\n  acbw.mu.Lock()\n  defer acbw.mu.Unlock()\n  go acbw.ac.connect()\n}<\/code><\/pre>\n<p>\u6700\u540e\u4f1a\u8c03\u7528addrConn.connect\u65b9\u6cd5\uff1a<\/p>\n<p><strong>grpc-go\/clientconn.go:786<\/strong><\/p>\n<pre><code class=\"go\">func (ac *addrConn) connect() error {\n  ac.mu.Lock()\n  if ac.state == connectivity.Shutdown {\n    ac.mu.Unlock()\n    return errConnClosing\n  }\n  if ac.state != connectivity.Idle {\n    ac.mu.Unlock()\n    return nil\n  }\n  ac.updateConnectivityState(connectivity.Connecting, nil)\n  ac.mu.Unlock()\n\n  ac.resetTransport()\n  return nil\n}<\/code><\/pre>\n<p>\u4ececonnect\u5f00\u59cb\u7684\u8c03\u7528\u94fe\u8def\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042295412\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u5728baseBalancer\u7684UpdateSubConnState\u65b9\u6cd5\u7684\u6700\u540e\uff0c\u66f4\u65b0\u4e86Picker\u4e3a\u81ea\u5b9a\u4e49\u7684Picker\uff1a<\/p>\n<p><strong>grpc-go\/balancer\/base\/balancer.go:221<\/strong><\/p>\n<pre><code class=\"go\">b.cc.UpdateState(balancer.State{ConnectivityState: b.state, Picker: b.picker})<\/code><\/pre>\n<p>\u5728addrConn\u65b9\u6cd5\u7684\u6700\u540e\u4f1a\u8c03\u7528ac.resetTransport()\u771f\u6b63\u7684\u8fdb\u884c\u8fde\u63a5\u7684\u521b\u5efa\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042295413\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u5f53\u8fde\u63a5\u5df2\u7ecf\u521b\u5efa\u597d\uff0c\u5904\u4e8eReady\u72b6\u6001\uff0c\u6700\u540e\u8c03\u7528baseBalancer.UpdateSubConnState\u65b9\u6cd5\uff0c\u6b64\u65f6s==connectivity.Ready\u4e3atrue\uff0c\u800coldS == connectivity.Ready\u4e3afalse\uff0c\u6240\u4ee5\u4f1a\u8c03\u7528b.regeneratePicker()\u65b9\u6cd5\uff1a<\/p>\n<pre><code class=\"go\">if (s == connectivity.Ready) != (oldS == connectivity.Ready) ||\n    b.state == connectivity.TransientFailure {\n    b.regeneratePicker()\n}<\/code><\/pre>\n<pre><code class=\"go\">func (b *baseBalancer) regeneratePicker() {\n  if b.state == connectivity.TransientFailure {\n    b.picker = NewErrPicker(b.mergeErrors())\n    return\n  }\n  readySCs := make(map[balancer.SubConn]SubConnInfo)\n\n  \/\/ Filter out all ready SCs from full subConn map.\n  for _, addr := range b.subConns.Keys() {\n    sci, _ := b.subConns.Get(addr)\n    sc := sci.(balancer.SubConn)\n    if st, ok := b.scStates[sc]; ok &amp;&amp; st == connectivity.Ready {\n      readySCs[sc] = SubConnInfo{Address: addr}\n    }\n  }\n  b.picker = b.pickerBuilder.Build(PickerBuildInfo{ReadySCs: readySCs})\n}<\/code><\/pre>\n<p>\u5728regeneratePicker\u4e2d\u83b7\u53d6\u4e86\u5904\u4e8econnectivity.Ready\u72b6\u6001\u53ef\u7528\u7684\u8fde\u63a5\uff0c\u540c\u65f6\u66f4\u65b0\u4e86picker\u3002\u8fd8\u8bb0\u5f97b.pickerBuilder\u5417\uff1fb.b.pickerBuilder\u4e3a\u5728go-zero\u4e2d\u81ea\u5b9a\u4e49\u5b9e\u73b0\u7684base.PickerBuilder\u63a5\u53e3\u3002<\/p>\n<p><strong>go-zero\/zrpc\/internal\/balancer\/p2c\/p2c.go:42<\/strong><\/p>\n<pre><code class=\"go\">func (b *p2cPickerBuilder) Build(info base.PickerBuildInfo) balancer.Picker {\n  readySCs := info.ReadySCs\n  if len(readySCs) == 0 {\n    return base.NewErrPicker(balancer.ErrNoSubConnAvailable)\n  }\n\n  var conns []*subConn\n  for conn, connInfo := range readySCs {\n    conns = append(conns, &amp;subConn{\n      addr:    connInfo.Address,\n      conn:    conn,\n      success: initSuccess,\n    })\n  }\n\n  return &amp;p2cPicker{\n    conns: conns,\n    r:     rand.New(rand.NewSource(time.Now().UnixNano())),\n    stamp: syncx.NewAtomicDuration(),\n  }\n}<\/code><\/pre>\n<p>\u6700\u540e\u628a\u81ea\u5b9a\u4e49\u7684Picker\u8d4b\u503c\u4e3a ClientConn.blockingpicker.picker\u5c5e\u6027\u3002<\/p>\n<p><strong>grpc-go\/balancer_conn_wrappers.go:347<\/strong><\/p>\n<pre><code class=\"go\">func (ccb *ccBalancerWrapper) UpdateState(s balancer.State) {\n  ccb.cc.blockingpicker.updatePicker(s.Picker)\n  ccb.cc.csMgr.updateState(s.ConnectivityState)\n}<\/code><\/pre>\n<h3>\u5982\u4f55\u9009\u62e9\u5df2\u521b\u5efa\u7684\u8fde\u63a5\uff1f<\/h3>\n<p>\u73b0\u5728\u5df2\u7ecf\u77e5\u9053\u4e86\u5982\u4f55\u521b\u5efa\u8fde\u63a5\uff0c\u4ee5\u53ca\u8fde\u63a5\u5176\u5b9e\u662f\u5728 <strong>baseBalancer.scStates<\/strong> \u4e2d\u7ba1\u7406\uff0c\u5f53\u8fde\u63a5\u7684\u72b6\u6001\u53d1\u751f\u53d8\u5316\uff0c\u5219\u4f1a\u66f4\u65b0 <strong>baseBalancer.scStates <\/strong> \u3002\u90a3\u4e48\u63a5\u4e0b\u6765\u6211\u4eec\u6765\u770b\u4e00\u4e0bgRPC\u662f\u5982\u4f55\u9009\u62e9\u4e00\u4e2a\u8fde\u63a5\u8fdb\u884c\u8bf7\u6c42\u7684\u53d1\u9001\u7684\u3002<\/p>\n<p>\u5f53gRPC\u5ba2\u6237\u7aef\u53d1\u8d77\u8c03\u7528\u7684\u65f6\u5019\uff0c\u4f1a\u8c03\u7528ClientConn\u7684Invoke\u65b9\u6cd5\uff0c\u4e00\u822c\u4e0d\u4f1a\u4e3b\u52a8\u4f7f\u7528\u8be5\u65b9\u6cd5\u8fdb\u884c\u8c03\u7528\uff0c\u8be5\u65b9\u6cd5\u7684\u8c03\u7528\u4e00\u822c\u662f\u81ea\u52a8\u751f\u6210\uff1a<\/p>\n<p><strong>grpc-go\/examples\/helloworld\/helloworld\/helloworld_grpc.pb.go:39<\/strong><\/p>\n<pre><code class=\"go\">func (c *greeterClient) SayHello(ctx context.Context, in *HelloRequest, opts ...grpc.CallOption) (*HelloReply, error) {\n  out := new(HelloReply)\n  err := c.cc.Invoke(ctx, &quot;\/helloworld.Greeter\/SayHello&quot;, in, out, opts...)\n  if err != nil {\n    return nil, err\n  }\n  return out, nil\n}<\/code><\/pre>\n<p>\u5982\u4e0b\u4e3a\u53d1\u8d77\u8bf7\u6c42\u7684\u8c03\u7528\u94fe\u8def\uff0c\u6700\u7ec8\u4f1a\u8c03\u7528p2cPicker.Pick\u65b9\u6cd5\u83b7\u53d6\u8fde\u63a5\uff0c\u6211\u4eec\u81ea\u5b9a\u4e49\u7684\u8d1f\u8f7d\u5747\u8861\u7b97\u6cd5\u4e00\u822c\u90fd\u5728Pick\u65b9\u6cd5\u4e2d\u5b9e\u73b0\uff0c\u83b7\u53d6\u5230\u8fde\u63a5\u4e4b\u540e\uff0c\u901a\u8fc7sendMsg\u53d1\u9001\u8bf7\u6c42\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042295414\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p><strong>grpc-go\/stream.go:945<\/strong><\/p>\n<pre><code class=\"go\">func (a *csAttempt) sendMsg(m interface{}, hdr, payld, data []byte) error {\n  cs := a.cs\n  if a.trInfo != nil {\n    a.mu.Lock()\n    if a.trInfo.tr != nil {\n      a.trInfo.tr.LazyLog(&amp;payload{sent: true, msg: m}, true)\n    }\n    a.mu.Unlock()\n  }\n  if err := a.t.Write(a.s, hdr, payld, &amp;transport.Options{Last: !cs.desc.ClientStreams}); err != nil {\n    if !cs.desc.ClientStreams {\n      return nil\n    }\n    return io.EOF\n  }\n  if a.statsHandler != nil {\n    a.statsHandler.HandleRPC(a.ctx, outPayload(true, m, data, payld, time.Now()))\n  }\n  if channelz.IsOn() {\n    a.t.IncrMsgSent()\n  }\n  return nil\n}<\/code><\/pre>\n<p>\u6e90\u7801\u5206\u6790\u5230\u6b64\u5c31\u7ed3\u675f\u4e86\uff0c\u7531\u4e8e\u7bc7\u5e45\u6709\u9650\u6ca1\u6cd5\u505a\u5230\u9762\u9762\u4ff1\u5230\uff0c\u6240\u4ee5\u672c\u6587\u53ea\u5217\u51fa\u4e86\u6e90\u7801\u4e2d\u7684\u4e3b\u8981\u8def\u5f84\u3002<\/p>\n<h2>\u7ed3\u675f\u8bed<\/h2>\n<p>Balancer\u76f8\u5173\u7684\u6e90\u7801\u8fd8\u662f\u6709\u70b9\u590d\u6742\u7684\uff0c\u7b14\u8005\u4e5f\u662f\u8bfb\u4e86\u597d\u51e0\u904d\u624d\u7406\u6e05\u8109\u7edc\uff0c\u6240\u4ee5\u5982\u679c\u8bfb\u4e86\u4e00\u4e24\u904d\u611f\u89c9\u6ca1\u6709\u5934\u7eea\u4e5f\u4e0d\u7528\u7740\u6025\uff0c\u5bf9\u7167\u6587\u7ae0\u7684\u8109\u7edc\u591a\u8bfb\u51e0\u904d\u5c31\u4e00\u5b9a\u80fd\u641e\u61c2\u3002<\/p>\n<p>\u5982\u679c\u6709\u7591\u95ee\u53ef\u4ee5\u968f\u65f6\u627e\u6211\u8ba8\u8bba\uff0c\u5728\u793e\u533a\u7fa4\u4e2d\u53ef\u4ee5\u641c\u7d22dawn_zhou\u627e\u5230\u6211\u3002<\/p>\n<p>\u5e0c\u671b\u672c\u7bc7\u6587\u7ae0\u5bf9\u4f60\u6709\u6240\u5e2e\u52a9\uff0c\u4f60\u7684\u70b9\u8d5e\u662f\u4f5c\u8005\u6301\u7eed\u8f93\u51fa\u7684\u6700\u5927\u52a8\u529b\u3002<\/p>\n<h2>\u9879\u76ee\u5730\u5740<\/h2>\n<p><a href=\"https:\/\/link.segmentfault.com\/?enc=u2K0qEdt8HvEzJPKVPhWag%3D%3D.AGYQJ5ICd5rW%2BBcO%2BQsHxmUxZDfqh%2Bvadp%2FmS0FJOos6DBQvAbpu35zArQY7P9aN\" rel=\"nofollow\">https:\/\/github.com\/zeromicro\/go-zero<\/a><\/p>\n<p>\u6b22\u8fce\u4f7f\u7528 <code>go-zero<\/code> \u5e76 <strong>star<\/strong> \u652f\u6301\u6211\u4eec\uff01<\/p>\n<h2>\u5fae\u4fe1\u4ea4\u6d41\u7fa4<\/h2>\n<p>\u5173\u6ce8\u300e<strong>\u5fae\u670d\u52a1\u5b9e\u8df5<\/strong>\u300f\u516c\u4f17\u53f7\u5e76\u70b9\u51fb <strong>\u4ea4\u6d41\u7fa4<\/strong> \u83b7\u53d6\u793e\u533a\u7fa4\u4e8c\u7ef4\u7801\u3002<\/p>\n<p><a href=\"https:\/\/segmentfault.com\/a\/1190000042295402\">https:\/\/segmentfault.com\/a\/1190000042295402<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e0a\u4e00\u7bc7\u6587\u7ae0\u4e00\u8d77\u5b66\u4e60\u4e86Resolver\u7684\u539f\u7406\u548c\u6e90\u7801\u5206\u6790\uff0c\u672c\u7bc7\u7ee7\u7eed\u548c\u5927\u5bb6\u4e00\u8d77\u5b66\u4e60\u4e0b\u548cResolver\u5173\u7cfb\u5bc6\u5207\u7684Ba [&hellip;]<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[],"tags":[],"class_list":["post-10006156","post","type-post","status-publish","format-standard","hentry"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10006156","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"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10006156"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10006156\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10006156"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10006156"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10006156"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}