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  1. JGroups
  2. JGRP-2533

Internal messages should use DONT_LOOPBACK

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    • Icon: Bug Bug
    • Resolution: Done
    • Icon: Minor Minor
    • 4.2.12, 5.1.6
    • 4.0.21, 4.2.11
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      Looping back internal messages is expensive: TP submits a task to the thread pool for the loopback itself, and then UNICAST3 submits another task to handle other regular message that might need to be delivered:

      OutOfMemoryError: unable to create new native thread
	at java.lang.Thread.start0(Native Method)
	at java.lang.Thread.start(Thread.java:717)
	at org.jgroups.protocols.TP.runInNewThread(TP.java:1410)
	at org.jgroups.protocols.TP.submitToThreadPool(TP.java:1394)
	at org.jgroups.protocols.TP.submitToThreadPool(TP.java:1391)
	at org.jgroups.protocols.TP.submitToThreadPool(TP.java:1377)
	at org.jgroups.protocols.UNICAST3.processInternalMessage(UNICAST3.java:776)
	at org.jgroups.protocols.UNICAST3.handleDataReceivedFromSelf(UNICAST3.java:766)
	at org.jgroups.protocols.UNICAST3.up(UNICAST3.java:387)
	at org.jgroups.protocols.pbcast.NAKACK2.up(NAKACK2.java:590)
	at org.jgroups.protocols.VERIFY_SUSPECT.up(VERIFY_SUSPECT.java:131)
	at org.jgroups.protocols.FD_ALL.up(FD_ALL.java:203)
	at org.jgroups.protocols.FD_SOCK.up(FD_SOCK.java:253)
	at org.jgroups.protocols.MERGE3.up(MERGE3.java:280)
	at org.jgroups.protocols.Discovery.up(Discovery.java:295)
	at org.jgroups.protocols.TP.passMessageUp(TP.java:1250)
	at org.jgroups.util.SubmitToThreadPool.lambda$loopback$0(SubmitToThreadPool.java:30)
	at java.lang.Thread.run(Thread.java:748)

      I noticed lots of protocols are sending messages with loopback enabled and fail to process those loopback messages when the JVM is unable to create more temporary threads:

      	at org.jgroups.protocols.FlowControl.sendCredit(FlowControl.java:480)

	at org.jgroups.protocols.FD_ALL$HeartbeatSender.run(FD_ALL.java:416)

	at org.jgroups.protocols.pbcast.STABLE.sendStableMessage(STABLE.java:668)

	at org.jgroups.protocols.pbcast.STABLE._sendStabilityMessage(STABLE.java:736)

	at org.jgroups.protocols.FD_SOCK.broadcastUnuspectMessage(FD_SOCK.java:710)

      I don't know if there are any consequences of those messages being dropped locally, but I don't think the possibility should exist at all, and that work should be done directly instead of sending a message to self.

      Note: line numbers are from 4.0.21.Final.

              rhn-engineering-bban Bela Ban
              dberinde@redhat.com Dan Berindei (Inactive)
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                Created:
                Updated:
                Resolved: