2 Replies Latest reply on Mar 6, 2014 12:02 AM by zhs

O} thread pool

zhs Mar 5, 2014 4:50 AM

Hi all,

I'm running WildFly 8 on GNU/Linux, I had a look at running threads via jstack, I found two thread pools related with epoll, stack traces are the same:

"XNIO-1 I/O-1" prio=10 tid=0x0000000002021800 nid=0x418e runnable [0x00007f0cf93c1000]

java.lang.Thread.State: RUNNABLE

at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)

at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:228)

at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:81)

at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:87)

- locked <0x00000000e7739e80> (a sun.nio.ch.Util$2)

- locked <0x00000000e7739e98> (a java.util.Collections$UnmodifiableSet)

- locked <0x00000000e6e284a8> (a sun.nio.ch.EPollSelectorImpl)

at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:98)

at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:102)

at org.xnio.nio.WorkerThread.run(WorkerThread.java:497)

"default I/O-1" prio=10 tid=0x0000000001f2a800 nid=0x4181 runnable [0x00007f0cf97ad000]

java.lang.Thread.State: RUNNABLE

at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)

at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:228)

at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:81)

at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:87)

- locked <0x00000000e5e2f078> (a sun.nio.ch.Util$2)

- locked <0x00000000e5e2f060> (a java.util.Collections$UnmodifiableSet)

- locked <0x00000000e609f920> (a sun.nio.ch.EPollSelectorImpl)

at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:98)

at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:102)

at org.xnio.nio.WorkerThread.run(WorkerThread.java:497)

I know the {default I/O} thread pool is from default worker, but what's the difference between it and {XNIO-1 I/O}?

Thanks

1. Re: What is the different between {XNIO-1 I/O} thread pool and {default I/O} thread pool

ctomc Mar 5, 2014 5:25 AM (in response to zhs)

Hey,

each worker has two thread pools.

one is controlled by io threads other via task threads.

In short, you can look io threads as acceptor threads (read/write) and task threads ones that do the actual work.

--
tomaz
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2. Re: What is the different between {XNIO-1 I/O} thread pool and {default I/O} thread pool

zhs Mar 6, 2014 12:02 AM (in response to ctomc)

Hi Tomaz,

I configured "<worker name="default" io-threads="8" task-max-threads="100"/>" in standalone.xml, I found there're {default I/O-1, ..., default I/O-8}, {default task-1, ..., default task-100}, and also {XNIO-1 I/O-1, XNIO-1 I/O-2} via jstack. I also had a look at http://undertow.io/documentation/core/overview.html and Workers - XNIO - Project Documentation Editor . I'm still not clear about it:
1) Are {XNIO-1 I/O-N} and {default I/O-N} threads all I/O threads?
2) What's the responsibility of them?

Thanks
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