[rabbitmq] rabbitmq client 개발시 주의사항 - Process Proxy 데몬 Hang

보통 소켓을 다루는 간단한 자바 애플리케이션 예시의 경우, socket을 close하지 않아도 자연스럽게 정리된다.

공식 RabbitMQ 자바 Client을 사용할 때 

publish 코드에서 사용하는 connection을 종료하지 않으면 계속 hang된다.

val connection = connectionFactory.newConnection
val channel    = connection.createChannel
channel.exchangeDeclare(exchange, builtinExchangeType, false)
messages.foreach { message =>
  channel.basicPublish(exchange, "", 
  MessageProperties.PERSISTENT_TEXT_PLAIN, message.getBytes("UTF-8"))
}

jstack을 통해  비동기 쓰레드 폴링을 확인할 수 있다.

"Process Proxy: RabbitPublisher" #473 prio=6 os_prio=31 tid=0x00007f854bd53000 nid=0x1572b runnable [0x000070000cde6000]

   java.lang.Thread.State: RUNNABLE

at sun.nio.ch.KQueue.keventPoll(Native Method)

at sun.nio.ch.KQueuePort$EventHandlerTask.poll(KQueuePort.java:196)

at sun.nio.ch.KQueuePort$EventHandlerTask.run(KQueuePort.java:276)

at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(AsynchronousChannelGroupImpl.java:112)

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)

at java.lang.Thread.run(Thread.java:748)

항상 자원을 close를 처리할 필요가 있다.

val connection = connectionFactory.newConnection
val channel    = connection.createChannel
channel.exchangeDeclare(exchange, builtinExchangeType, false)
messages.foreach { message =>
  channel.basicPublish(exchange, "", 
  MessageProperties.PERSISTENT_TEXT_PLAIN, message.getBytes("UTF-8"))
}
channel.close()
connection.close()