我有一个生产 MongoDB 2.4，它在日志中出现此错误：
SocketException handling request, closing client connection: 9001 socket exception [SEND_ERROR] server [127.0.0.1:37934]
客户端的日志报告连接超时。
mongod --version报告 v2.4.10（我在 Debian jessie 上；MongoDB 是从 jessie 存储库安装的）并且net.ipv4.tcp_keepalive_timesysctl 设置为 300，如建议的那样Mongo 日志中的 SocketException。此外，在重新启动 MongoDB 和应用程序后直接触发数据库查询时仍然会出现错误，这对我来说表明这不是 SERVER-5632（上面的问题中提到）。
/proc/pid/limits报告除堆栈大小、核心文件大小、进程、锁定内存、待处理信号、消息队列大小、nice 和实时优先级以及打开文件之外的所有内容均不受限制。特别是最后一个，软限制为 1024，硬限制为 4096，这不是 MongoDB 文档推荐的，但无论如何应该不是问题，因为 ls /proc/pid/fd | wc -l只报告了 29 个打开的 fds。
free -g报告 3 GB 可用内存、+/- 缓冲区和缓存。重新启动整个服务器似乎有帮助有些短暂一段时间后，情况又会变得一样糟糕。以下是日志中的一段：
Wed Mar 1 20:14:17.466 [conn1] authenticate db: pumpio { authenticate: 1, user: "pump.io", nonce: "7ac439ffd4c01a6d", key: "abe7862c7eb1f9765ebaa007d7c20ec2" }
Wed Mar 1 20:14:26.445 [conn1] command pumpio.$cmd command: { authenticate: 1, user: "pump.io", nonce: "7ac439ffd4c01a6d", key: "abe7862c7eb1f9765ebaa007d7c20ec2" } ntoreturn:1 keyUpdates:0 locks(micros) W:8978364 r:412 reslen:74 8979ms
Wed Mar 1 20:14:41.809 [initandlisten] connection accepted from 127.0.0.1:58216 #2 (2 connections now open)
Wed Mar 1 20:14:46.302 [initandlisten] connection accepted from 127.0.0.1:58218 #3 (3 connections now open)
Wed Mar 1 20:14:49.212 [initandlisten] connection accepted from 127.0.0.1:58220 #4 (4 connections now open)
Wed Mar 1 20:14:49.212 [initandlisten] connection accepted from 127.0.0.1:58222 #5 (5 connections now open)
Wed Mar 1 20:14:49.212 [initandlisten] connection accepted from 127.0.0.1:58224 #6 (6 connections now open)
Wed Mar 1 20:14:49.213 [initandlisten] connection accepted from 127.0.0.1:58226 #7 (7 connections now open)
Wed Mar 1 20:14:49.213 [initandlisten] connection accepted from 127.0.0.1:58228 #8 (8 connections now open)
Wed Mar 1 20:14:49.213 [initandlisten] connection accepted from 127.0.0.1:58230 #9 (9 connections now open)
Wed Mar 1 20:14:49.213 [initandlisten] connection accepted from 127.0.0.1:58232 #10 (10 connections now open)
Wed Mar 1 20:14:49.213 [initandlisten] connection accepted from 127.0.0.1:58234 #11 (11 connections now open)
Wed Mar 1 20:14:49.213 [initandlisten] connection accepted from 127.0.0.1:58236 #12 (12 connections now open)
Wed Mar 1 20:14:50.685 [conn1] query pumpio.session query: { _id: "9n_7gseqgT8i07tQbnBj7gNgURdQNmS8" } ntoreturn:1 idhack:1 keyUpdates:0 locks(micros) r:13911898 reslen:202 17129ms
Wed Mar 1 20:14:50.695 [conn2] authenticate db: pumpio { authenticate: 1, user: "pump.io", nonce: "7e918deb40e23f92", key: "0b4b2d78fa404e594dc1d066c9402cc4" }
Wed Mar 1 20:14:52.960 [conn1] SocketException handling request, closing client connection: 9001 socket exception [SEND_ERROR] server [127.0.0.1:58214]
Wed Mar 1 20:14:52.960 [conn7] assertion 16550 not authorized for query on reportr.system.indexes ns:reportr.system.indexes query:{ ns: "reportr.alerts" }
Wed Mar 1 20:14:52.960 [conn12] assertion 16550 not authorized for query on reportr.system.indexes ns:reportr.system.indexes query:{ ns: "reportr.alerts" }
Wed Mar 1 20:14:52.960 [conn5] assertion 16550 not authorized for query on reportr.system.indexes ns:reportr.system.indexes query:{ ns: "reportr.events" }
Wed Mar 1 20:14:52.960 [conn10] assertion 16550 not authorized for query on reportr.system.indexes ns:reportr.system.indexes query:{ ns: "reportr.events" }
Wed Mar 1 20:14:58.713 [initandlisten] connection accepted from 127.0.0.1:58238 #13 (12 connections now open)
Wed Mar 1 20:14:58.715 [conn13] authenticate db: pumpio { authenticate: 1, user: "pump.io", nonce: "fe508e5612e933fa", key: "492c9d11f582c045941da7f7eb16b8bd" }
Wed Mar 1 20:15:07.599 [conn2] update pumpio.session query: { _id: "i_vJ67QJA56LsQvLMF8GuiosMHUj7--P" } update: { cookie: { originalMaxAge: null, expires: null, httpOnly: true, path: "/" }, _id: "i_vJ67QJA56LsQvLMF8GuiosMHUj7--P" } idhack:1 nupdated:1 upsert:1 keyUpdates:0 locks(micros) w:16896964 16897ms
Wed Mar 1 20:15:07.600 [conn2] SocketException handling request, closing client connection: 9001 socket exception [SEND_ERROR] server [127.0.0.1:58216]
Wed Mar 1 20:15:07.600 [conn13] command pumpio.$cmd command: { authenticate: 1, user: "pump.io", nonce: "fe508e5612e933fa", key: "492c9d11f582c045941da7f7eb16b8bd" } ntoreturn:1 keyUpdates:0 locks(micros) r:1225 reslen:74 8885ms
Wed Mar 1 20:15:08.050 [conn13] update pumpio.session query: { _id: "deiIhAPc1vaXYZ_JzU72slghiCMOu1Zf" } update: { cookie: { originalMaxAge: null, expires: null, httpOnly: true, path: "/" }, _id: "deiIhAPc1vaXYZ_JzU72slghiCMOu1Zf" } idhack:1 nupdated:1 upsert:1 keyUpdates:0 locks(micros) w:109 447ms
Wed Mar 1 20:15:15.592 [TTLMonitor] query local.system.indexes query: { expireAfterSeconds: { $exists: true } } ntoreturn:0 ntoskip:0 nscanned:0 keyUpdates:0 locks(micros) r:142680 nreturned:0 reslen:20 142ms
Wed Mar 1 20:15:30.773 [conn13] query pumpio.recentdialbackrequests query: { _id: 0 } ntoreturn:1 idhack:1 keyUpdates:0 locks(micros) r:2751358 reslen:95317 2751ms
Wed Mar 1 20:16:14.855 [conn13] query pumpio.comment query: { _uuid: "oudHqMliREq5HSXd-7N62Q" } ntoreturn:1000 ntoskip:0 nscanned:1 keyUpdates:0 locks(micros) r:3247907 nreturned:1 reslen:900 4951ms
Wed Mar 1 20:16:14.855 [conn13] SocketException handling request, closing client connection: 9001 socket exception [SEND_ERROR] server [127.0.0.1:58238]
这是我重启 MongoDB 服务器和应用服务器之后出现的情况。它们都在同一台主机上，应用连接到它们localhost以发出数据库查询。
知道发生什么事了吗？