在MongoDB中打开连接的SocketTimeout
我有一个Java应用程序在MongoDB上执行一些聚合，但有时它只是挂起并抛出一个SocketTimeoutexception。 在exception之后，应用程序将运行正常（稍微，然后它可能会再次引发exception）。
我刚刚发现这个解释似乎是可能的原因，但我不确定。
我初始化MongoClient并保持与DB的连接打开。 我不确定这是否是一个问题，我应该每次都得到数据库，然后让数据库被垃圾收集（并关闭连接）。
另一种方法可能是定期ping Mongo以保持连接池“新鲜”。
使用的客户端是这样的：
public class DbClient { private static MongoClient mongoClient; private static MongoDatabase db; private DbClient() {} public static void init() throws Exception { mongoClient = new MongoClient(); } public static MongoDatabase getDB() { if(mongoClient == null) throw new IllegalStateException("Client not initialized!"); if(db == null) { db = mongoClient.getDatabase("my_db"); } return db; } } 这是SocketTimeout的可能原因吗？
这是抛出的exception：
09:20:45.742 [qtp605535417-46] INFO org.mongodb.driver.connection - Closed connection [connectionId{localValue:16, serverValue:6562}] to myapp.com:27017 because there was a socket exception raised by this connection. 09:20:45.743 [qtp605535417-46] ERROR myapp.service.Api - Error processing request com.mongodb.MongoSocketReadTimeoutException: Timeout while receiving message at com.mongodb.connection.InternalStreamConnection.translateReadException(InternalStreamConnection.java:474) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.connection.InternalStreamConnection.receiveMessage(InternalStreamConnection.java:225) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.connection.UsageTrackingInternalConnection.receiveMessage(UsageTrackingInternalConnection.java:102) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.connection.DefaultConnectionPool$PooledConnection.receiveMessage(DefaultConnectionPool.java:435) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.connection.CommandProtocol.execute(CommandProtocol.java:112) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.connection.DefaultServer$DefaultServerProtocolExecutor.execute(DefaultServer.java:159) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.connection.DefaultServerConnection.executeProtocol(DefaultServerConnection.java:286) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.connection.DefaultServerConnection.command(DefaultServerConnection.java:173) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:215) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:206) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:112) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.operation.FindOperation$1.call(FindOperation.java:487) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.operation.FindOperation$1.call(FindOperation.java:482) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.operation.OperationHelper.withConnectionSource(OperationHelper.java:239) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.operation.OperationHelper.withConnection(OperationHelper.java:212) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.operation.FindOperation.execute(FindOperation.java:482) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.operation.FindOperation.execute(FindOperation.java:79) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.Mongo.execute(Mongo.java:772) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.Mongo$2.execute(Mongo.java:759) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.OperationIterable.iterator(OperationIterable.java:47) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.FindIterableImpl.iterator(FindIterableImpl.java:143) ~[mongo-java-driver-3.2.2.jar!/:na] at myapp.common.db.service.dao.AnalysisMongoImpl.getAnalysis(AnalysisMongoImpl.java:66) ~[common-0.2.0-SNAPSHOT.jar!/:na] at myapp.common.db.service.AnalysisServiceImpl.getAnalysis(AnalysisServiceImpl.java:31) ~[common-0.2.0-SNAPSHOT.jar!/:na] at myapp.aggregator.service.Api$1.handle(Api.java:88) ~[aggregator-0.2.0-SNAPSHOT.jar!/:na] at spark.webserver.MatcherFilter.doFilter(MatcherFilter.java:139) [spark-core-1.1.1.jar!/:na] at spark.webserver.JettyHandler.doHandle(JettyHandler.java:54) [spark-core-1.1.1.jar!/:na] at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:179) [jetty-server-9.0.2.v20130417.jar!/:9.0.2.v20130417] at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:136) [jetty-server-9.0.2.v20130417.jar!/:9.0.2.v20130417] at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97) [jetty-server-9.0.2.v20130417.jar!/:9.0.2.v20130417] at org.eclipse.jetty.server.Server.handle(Server.java:451) [jetty-server-9.0.2.v20130417.jar!/:9.0.2.v20130417] at org.eclipse.jetty.server.HttpChannel.run(HttpChannel.java:252) [jetty-server-9.0.2.v20130417.jar!/:9.0.2.v20130417] at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:266) [jetty-server-9.0.2.v20130417.jar!/:9.0.2.v20130417] at org.eclipse.jetty.io.AbstractConnection$ReadCallback.run(AbstractConnection.java:240) [jetty-io-9.0.2.v20130417.jar!/:9.0.2.v20130417] at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:596) [jetty-util-9.0.2.v20130417.jar!/:9.0.2.v20130417] at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:527) [jetty-util-9.0.2.v20130417.jar!/:9.0.2.v20130417] at java.lang.Thread.run(Thread.java:745) [na:1.7.0_95] Caused by: java.net.SocketTimeoutException: Read timed out at java.net.SocketInputStream.socketRead0(Native Method) ~[na:1.7.0_95] at java.net.SocketInputStream.read(SocketInputStream.java:152) ~[na:1.7.0_95] at java.net.SocketInputStream.read(SocketInputStream.java:122) ~[na:1.7.0_95] at com.mongodb.connection.SocketStream.read(SocketStream.java:85) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.connection.InternalStreamConnection.receiveResponseBuffers(InternalStreamConnection.java:491) ~[mongo-java-driver-3.2.2.jar!/:na] at com.mongodb.connection.InternalStreamConnection.receiveMessage(InternalStreamConnection.java:221) ~[mongo-java-driver-3.2.2.jar!/:na] ... 34 common frames omitted
经过几次尝试后，我发现Azure的Load Balancer存在问题。
在60秒不活动后，它将断开任何挂起的TCP连接。
在进一步挖掘之后，我发现了MongoDB诊断FAQ的这篇文章，并且我已经将tcp keepalive设置为120s：
sudo sysctl -w net.ipv4.tcp_keepalive_time=
我还将MongoClient的socketKeepAlive设置为true：
MongoClientOptions.Builder options = MongoClientOptions.builder(); options.socketKeepAlive(true); mongoClient = new MongoClient(mongoAddress, options.build());
经过这些修复后问题似乎消失了！
如果在客户端和服务器之间或者没有其他合理原因的分片集群或副本集的成员之间遇到套接字错误，请检查TCP keepalive值（例如，Linux系统上的tcp_keepalive_time值）。 常见的保持活动时间为7200秒（2小时）; 但是，不同的发行版和macOS可能有不同的设置。
对于MongoDB，您将获得更好的结果，保持期更短，大约120秒（两分钟）。
你已经安装了mongodb你必须在Linux上运行这个命令
sudo sysctl -w net.ipv4.tcp_keepalive_time = 120