simply lock and unlock JGroups lock repeatedly will create chaos ---------------------------------------------------------------- Key: JGRP-2364 URL: https://issues.jboss.org/browse/JGRP-2364 Project: JGroups Issue Type: Bug Affects Versions: 4.1.1 Environment: JDK: 1.8 JGroups: 4.1.1 Lock: CENTRAL_LOCK Reporter: Yong Deng Assignee: Bela Ban Priority: Major Fix For: 4.1.2 Attachments: LockSimpleTest.java I have one simple use case to reproduce the issue. In same thread, just lock/unlock the lock repeatedly. Turn the log level to TRACE, you will find the communication chaos between the client and the coordinate. *JGroups unlock will return immediately after sending out RELEASE_LOCK currently. Why unlock don’t wait and only return after receiving the RELEASE_LOCK_OK response?* * Current log: {code:java} 16:56:40,399 TRACE [CENTRAL_LOCK] A --> A: GRANT_LOCK[sample-lock, lock_id=1, owner=A::31, trylock, timeout=10000] 16:56:40,404 TRACE [CENTRAL_LOCK] A <-- A: GRANT_LOCK[sample-lock, lock_id=1, owner=A::31, trylock, timeout=10000, sender=A] 16:56:40,410 TRACE [CENTRAL_LOCK] A --> A: LOCK_GRANTED[sample-lock, lock_id=1, owner=A::31] 16:56:40,411 TRACE [CENTRAL_LOCK] A <-- A: LOCK_GRANTED[sample-lock, lock_id=1, owner=A::31, sender=A] 16:56:40,413 TRACE [CENTRAL_LOCK] A --> A: RELEASE_LOCK[sample-lock, lock_id=1, owner=A::31] 16:56:40,414 TRACE [CENTRAL_LOCK] A <-- A: RELEASE_LOCK[sample-lock, lock_id=1, owner=A::31, sender=A] 16:56:40,414 TRACE [CENTRAL_LOCK] A --> A: RELEASE_LOCK[sample-lock, lock_id=1, owner=A::31] 16:56:40,415 TRACE [CENTRAL_LOCK] A --> A: RELEASE_LOCK_OK[sample-lock, lock_id=1, owner=A::31] 16:56:40,415 TRACE [CENTRAL_LOCK] A --> A: RELEASE_LOCK[sample-lock, lock_id=1, owner=A::31] {code} * The expected log: {code:java} 2019-07-24 17:01:52,849 TRACE [org.jgroups.protocols.CENTRAL_LOCK] [A] --> [A] GRANT_LOCK [sample-lock, lock_id=1, owner=A::63, trylock (timeout=10000) 2019-07-24 17:01:52,849 TRACE [org.jgroups.protocols.CENTRAL_LOCK] [A] <-- [A] GRANT_LOCK [sample-lock, lock_id=1, owner=A::63, trylock (timeout=10000) 2019-07-24 17:01:52,852 TRACE [org.jgroups.protocols.CENTRAL_LOCK] [A] --> [A] LOCK_GRANTED [sample-lock, lock_id=1, owner=A::63 ] 2019-07-24 17:01:52,852 TRACE [org.jgroups.protocols.CENTRAL_LOCK] [A] <-- [A] LOCK_GRANTED [sample-lock, lock_id=1, owner=A::63 ] 2019-07-24 17:01:52,853 TRACE [org.jgroups.protocols.CENTRAL_LOCK] [A] --> [A] RELEASE_LOCK [sample-lock, lock_id=1, owner=A::63 ] 2019-07-24 17:01:52,853 TRACE [org.jgroups.protocols.CENTRAL_LOCK] [A] <-- [A] RELEASE_LOCK [sample-lock, lock_id=1, owner=A::63 ] 2019-07-24 17:01:52,853 TRACE [org.jgroups.protocols.CENTRAL_LOCK] [A] --> [A] RELEASE_LOCK_OK [sample-lock, lock_id=1, owner=A::63 ] 2019-07-24 17:01:52,854 TRACE [org.jgroups.protocols.CENTRAL_LOCK] [A] <-- [A] RELEASE_LOCK_OK [sample-lock, lock_id=1, owner=A::63 ] {code}