[GitHub] merlimat opened a new pull request #1108: Fixed race condition between write operation and send timeout

[GitBox <gi...@apache.org>]

merlimat opened a new pull request #1108: Fixed race condition between write operation and send timeout
URL: https://github.com/apache/incubator-pulsar/pull/1108
 
 
   ### Motivation
   
   There is a possible race condition between a send operation getting written on a socket channel and getting timed-out at the same time. The problem is reproducible by setting very low timeout (eg: 10ms) at sustained publish rate. 
   
   The reason of the race condition is that we pass the instance of the `OpSendMsg` to the io-thread to get the `ByteBuf` to write into the socket but the timeout is touching it as well. We should instead take a reference on the `ByteBuf` itself for which we have already a reference increased for the write operation.
   
   This is the seen exception:
   
   ```
   2018-01-24 14:24:08,738 - WARN  - [pulsar-client-io-2-2:Slf4JLogger@146] - A task raised an exception. Task: org.apache.pulsar.client.impl.ProducerImpl$WriteInEventLoopCallback@4b2480e1
   java.lang.NullPointerException: msg
   	at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:785)
   	at org.apache.pulsar.client.impl.ProducerImpl$WriteInEventLoopCallback.run(ProducerImpl.java:462)
   	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
   	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404)
   	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:463)
   	at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:886)
   	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
   	at java.lang.Thread.run(Thread.java:745)
   ```

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