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  1. Kafka
  2. KAFKA-3501

Console consumer process hangs on SIGINT



    • Bug
    • Status: Resolved
    • Major
    • Resolution: Fixed
    • consumer, core
    • None
    • Ubuntu 12.04.5 LTS
      OpenJDK Runtime Environment (IcedTea 2.6.3) (7u91-2.6.3-0ubuntu0.12.04.1)
      OpenJDK 64-Bit Server VM (build 24.91-b01, mixed mode)
    • Patch


      Sometimes when running the `kafka-console-consumer` script inside a pipe and trying to stop it with a `SIGINT` (`ctrl+c`), the process will not stop.

      ubuntu@xxx:~$ kafka-console-consumer --zookeeper localhost --topic topic --from-beginning | grep "pattern"
      ^CUnable to write to standard out, closing consumer.
      # process is still running

      When looking at the various threads running on the JVM, I noticed that one user thread is waiting on a latch preventing the JVM from shutting down:

      "Thread-6" prio=10 tid=0x00007f258c016000 nid=0x289f waiting on condition [0x00007f259aee3000]
         java.lang.Thread.State: WAITING (parking)
      	at sun.misc.Unsafe.park(Native Method)
      	- parking to wait for  <0x00000000d6640c80> (a java.util.concurrent.CountDownLatch$Sync)
      	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
      	at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:834)
      	at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:994)
      	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1303)
      	at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:236)
      	at kafka.tools.ConsoleConsumer$$anon$1.run(ConsoleConsumer.scala:101)
      "main" prio=10 tid=0x00007f25c400e000 nid=0x2878 waiting for monitor entry [0x00007f25cbefc000]
         java.lang.Thread.State: BLOCKED (on object monitor)
      	at java.lang.Shutdown.exit(Shutdown.java:212)
      	- waiting to lock <0x00000000d6974308> (a java.lang.Class for java.lang.Shutdown)
      	at java.lang.Runtime.exit(Runtime.java:109)
      	at java.lang.System.exit(System.java:962)
      	at kafka.tools.ConsoleConsumer$.checkErr(ConsoleConsumer.scala:149)
      	at kafka.tools.ConsoleConsumer$.process(ConsoleConsumer.scala:136)
      	at kafka.tools.ConsoleConsumer$.run(ConsoleConsumer.scala:69)
      	at kafka.tools.ConsoleConsumer$.main(ConsoleConsumer.scala:47)
      	at kafka.tools.ConsoleConsumer.main(ConsoleConsumer.scala)

      I believe the standard output linked to the defunct grep process get closed and triggers a `System.exit(1)` that prevents the latch from getting count down and therefore the main thread to hang on forever:


      def checkErr(formatter: MessageFormatter) {
      if (System.out.checkError())

      { // This means no one is listening to our output stream any more, time to shutdown System.err.println("Unable to write to standard out, closing consumer.") formatter.close() System.exit(1) }



      This only happens when `System.out` is checked for errors after consuming a message and before the consumer get closed, definitely a race condition that is most likely to happen when messages are consumed at a high throughput.


        1. jstack.txt
          15 kB
          Sébastien Launay

        Issue Links



              nehanarkhede Neha Narkhede
              yabon Sébastien Launay
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