我在 Centos 7.2 上有一个 Varnish 4.0.3 服务器。Varnish 配置了三个后端。我收到来自 Varnish 的间歇性 503。我在 503 事件期间提取了一个 tcpdump,我看到:
- 消费者向清漆提出要求
- Varnish 打开套接字到后端。
- 后端在 < 500 毫秒内响应
- Varnish 向后端发送一个 ACK,FIN。
- Varnish 向消费者发送 503。
- 后端向 Varnish 发送 ACK,FIN
失败的请求在根本上看起来与成功的请求没有什么不同。失败率约为每 20k 个请求 1 个。
- Begin req 2795361 rxreq
- Timestamp Start: 1464106437.502383 0.000000 0.000000
- Timestamp Req: 1464106437.502383 0.000000 0.000000
- ReqStart 10.14.X.X 43190
- ReqMethod GET
- ReqURL /service/v2/service/parameter/parameter/parameter
- ReqProtocol HTTP/1.1
- ReqHeader Accept: application/json
- ReqHeader Content-Type: application/json
- ReqHeader Host: UpsteamLoadBalancer:6081
- ReqHeader Connection: Keep-Alive
- ReqHeader User-Agent: Apache-HttpClient/4.2.4 (java 1.5)
- ReqHeader X-Forwarded-For: 10.14.X.X
- VCL_call RECV
- ReqURL /service/v2/service/parameter/parameter/parameter
- ReqUnset X-Forwarded-For: 10.14.X.X
- ReqHeader X-Forwarded-For: 10.14.X.X
- VCL_return hash
- VCL_call HASH
- VCL_return lookup
- Debug "XXXX MISS"
- VCL_call MISS
- VCL_return fetch
- Link bereq 2795368 fetch
- Timestamp Fetch: 1464106442.526296 5.023913 5.023913
- Timestamp Process: 1464106442.526311 5.023929 0.000015
- RespHeader Date: Tue, 24 May 2016 16:14:02 GMT
- RespHeader Server: Varnish
- RespHeader X-Varnish: 2795367
- RespProtocol HTTP/1.1
- RespStatus 503
- RespReason Service Unavailable
- RespReason Service Unavailable
- VCL_call SYNTH
- RespHeader Content-Type: text/html; charset=utf-8
- RespHeader Retry-After: 5
- VCL_return deliver
- RespHeader Content-Length: 281
- Debug "RES_MODE 2"
- RespHeader Connection: keep-alive
- Timestamp Resp: 1464106442.526356 5.023974 0.000045
- ReqAcct 290 0 290 211 281 492
- End