The max-connections property configures the maximum number of client connections that can be created on a server.
If a set of clients is attempting to create >800 connections to the same server either during an operation or while prefilling its pool of connections, a warning like this is logged on the server: [warning 2017/02/06 13:12:34.846 PST server-1 <Handshaker 0.0.0.0/0.0.0.0:50780 Thread 0> tid=0x3c] Rejected connection from /xxxxx because current connection count of 800 is greater than or equal to the configured max of 800 And a warning like this is logged on the client: [warning 2017/02/06 13:29:35.048 PST client-feeder <Thread-13> tid=0x1e] Could not create a new connection to server: xxxxx(server-1:8657)<v16>:21156 refused connection: exceeded max-connections 800 And an exception like one of these is thrown on that client: During an operation: com.gemstone.gemfire.cache.client.NoAvailableServersException: com.gemstone.gemfire.cache.client.ServerRefusedConnectionException: xxxxx(server-1:8657)<v16>:21156 refused connection: exceeded max-connections 800 ... at com.gemstone.gemfire.internal.cache.LocalRegion.put(LocalRegion.java:1580) at com.gemstone.gemfire.internal.cache.AbstractRegion.put(AbstractRegion.java:327) at TestClient$1.run(TestClient.java:74) at java.lang.Thread.run(Thread.java:745) Caused by: com.gemstone.gemfire.cache.client.ServerRefusedConnectionException: xxxxx(server-1:8657)<v16>:21156 refused connection: exceeded max-connections 800 at com.gemstone.gemfire.internal.cache.tier.sockets.HandShake.readMessage(HandShake.java:1466) at com.gemstone.gemfire.internal.cache.tier.sockets.HandShake.greet(HandShake.java:1317) at com.gemstone.gemfire.cache.client.internal.ConnectionImpl.connect(ConnectionImpl.java:112) at com.gemstone.gemfire.cache.client.internal.ConnectionFactoryImpl.createClientToServerConnection(ConnectionFactoryImpl.java:134) at com.gemstone.gemfire.cache.client.internal.ConnectionFactoryImpl.createClientToServerConnection(ConnectionFactoryImpl.java:252) at com.gemstone.gemfire.cache.client.internal.pooling.ConnectionManagerImpl.borrowConnection(ConnectionManagerImpl.java:214) During prefill: [info 2017/02/06 13:48:46.772 PST client-feeder <poolTimer-pool-3> tid=0x16] Error prefilling connections : com.gemstone.gemfire.cache.client.ServerRefusedConnectionException: xxxxx(server-1:8796)<v19>:9152 refused connection: exceeded max-connections 800 com.gemstone.gemfire.cache.client.ServerRefusedConnectionException: xxxxx(server-1:8796)<v19>:9152 refused connection: exceeded max-connections 16 at com.gemstone.gemfire.internal.cache.tier.sockets.HandShake.readMessage(HandShake.java:1466) at com.gemstone.gemfire.internal.cache.tier.sockets.HandShake.greet(HandShake.java:1317) at com.gemstone.gemfire.cache.client.internal.ConnectionImpl.connect(ConnectionImpl.java:112) at com.gemstone.gemfire.cache.client.internal.ConnectionFactoryImpl.createClientToServerConnection(ConnectionFactoryImpl.java:134) at com.gemstone.gemfire.cache.client.internal.ConnectionFactoryImpl.createClientToServerConnection(ConnectionFactoryImpl.java:252) at com.gemstone.gemfire.cache.client.internal.pooling.ConnectionManagerImpl.prefillConnection(ConnectionManagerImpl.java:794) at com.gemstone.gemfire.cache.client.internal.pooling.ConnectionManagerImpl.prefill(ConnectionManagerImpl.java:737) at com.gemstone.gemfire.cache.client.internal.pooling.ConnectionManagerImpl$PrefillConnectionsTask.run2(ConnectionManagerImpl.java:888) Either way, the server won't allow additional connections to it, and the client operation will fail. There are a few things you can do: - increase max-connections to accomodate all the client connections - handle the NoAvailableServersException by retrying. The hope is that the retry will find an available connection rather than having to create a new one - limit the number of client connections with the max-connections pool attribute. If max-connections is set and all client connections are in use, a thread will wait for an available connection (for up to 10000 ms by default controlled by the free-connection-timeout pool attribute) before throwing an exception. Also, just because there are 800 threads doing operations doesn't necessarily mean there are 800 connections. Each client has a pool of connections that its threads can use. In the extreme case, if there are 800 threads on a single client, its pretty unlikely that there will be 800 connections. Instead, its likely that a thread will find an available existing connection rather than having to create a new one. Thanks, Barry Oglesby On Mon, Feb 6, 2017 at 12:20 PM, Goutam Tadi <gt...@pivotal.io> wrote: > Hi, > > I have a couple of questions regarding max-connections attribute in > cache.xml. > > 1. If max-connections is set to 800 by default, does that mean if I have > 800+ region.put() methods from multiple clients in parallel, Will this > cause issue to some of the inserts or requests from server ? > > 2. If I would like to try multi threading (inserts/puts) by buffering rows > to some size of 1MB and use putAll() to insert batch of rows into a region > with max-connections set to 800 by default, will this cause issue to the > client, if the client launches 800+ threads of batch inserts ? > > > Thanks, > Goutam Tadi. > -- > Regards, > *Goutam Tadi.* >
