Socket SO TIMEOUT

External

• https://docs.oracle.com/javase/8/docs/api/java/net/SocketOptions.html

Internal

• DatagramSocket SO_TIMEOUT
• TCP Socket SO_TIMEOUT
• Tomcat Connector soTimeout

Overview

SO_TIMEOUT defines the timeout for waiting for data - the a maximum period inactivity between two consecutive data packets. It is specified in milliseconds. A timeout value of zero is interpreted as an infinite timeout.

At java.net API level, it can be set on a socket with setSoTimeout(int timeout) throws SocketException and read with getSoTimeout(). This method call enables/disables SO_TIMEOUT with the specified timeout, in milliseconds. With this option set to a non-zero timeout, a read() call on the InputStream associated with this Socket will block for only this amount of time. If the timeout expires, a java.net.SocketTimeoutException is raised, though the Socket is still valid. The option must be enabled prior to entering the blocking operation to have effect. The timeout must be > 0. A timeout of zero is interpreted as an infinite timeout.

SO_TIMEOUT and Writing

SO_TIMEOUT does not help when the socket is writing. I captured the following thread dump where soTimeout() was set to 20 seconds, but the client got stuck for about 17 minutes. Stack trace below. The explanation is here: [Java Socket#HangInSocketWriteCall].

"CLD Runner 0 Thread" prio=10 tid=0x00007f5f5c3c1800 nid=0x349f runnable [0x00007f5f5480e000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.FileDispatcherImpl.write0(Native Method)
        at sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:47)
        at sun.nio.ch.IOUtil.writeFromNativeBuffer(IOUtil.java:94)
        at sun.nio.ch.IOUtil.write(IOUtil.java:65)
        at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:466)
        - locked <0x00000000fd9f3a00> (a java.lang.Object)
        at java.nio.channels.Channels.writeFullyImpl(Channels.java:78)
        at java.nio.channels.Channels.writeFully(Channels.java:98)
        - locked <0x00000000fd9f39b8> (a java.lang.Object)
        at java.nio.channels.Channels.access$000(Channels.java:61)
        at java.nio.channels.Channels$1.write(Channels.java:174)
        - locked <0x00000000fd9f3b08> (a java.nio.channels.Channels$1)
        at java.io.BufferedOutputStream.write(BufferedOutputStream.java:122)
        - locked <0x00000000fd9f3af0> (a java.io.BufferedOutputStream)
        at java.io.FilterOutputStream.write(FilterOutputStream.java:97)
        at org.infinispan.client.hotrod.impl.transport.tcp.TcpTransport.writeBytes(TcpTransport.java:134)
        at org.infinispan.client.hotrod.impl.transport.AbstractTransport.writeArray(AbstractTransport.java:98)
        at org.infinispan.client.hotrod.impl.operations.AbstractKeyValueOperation.sendPutOperation(AbstractKeyValueOperation.java:44)
        at org.infinispan.client.hotrod.impl.operations.PutOperation.executeOperation(PutOperation.java:30)
        at org.infinispan.client.hotrod.impl.operations.PutOperation.executeOperation(PutOperation.java:19)
        at org.infinispan.client.hotrod.impl.operations.RetryOnFailureOperation.execute(RetryOnFailureOperation.java:49)
        at org.infinispan.client.hotrod.impl.RemoteCacheImpl.put(RemoteCacheImpl.java:237)
        at org.infinispan.client.hotrod.impl.RemoteCacheSupport.put(RemoteCacheSupport.java:79)
        at com.novaordis.cld.service.infinispan.InfinispanService.set(InfinispanService.java:62)
        at com.novaordis.cld.operations.Write.perform(Write.java:46)
        at com.novaordis.cld.SingleThreadedRunner.loopUntilStoppedOrOutOfOperations(SingleThreadedRunner.java:166)
        at com.novaordis.cld.SingleThreadedRunner.run(SingleThreadedRunner.java:75)
        at java.lang.Thread.run(Thread.java:724)

Subjects

• Setting socket SO_TIMEOUT with Apache HttpClient