Stefan Egli created OAK-4532:
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Summary: race-condition in commit-rate-limiter
Key: OAK-4532
URL: https://issues.apache.org/jira/browse/OAK-4532
Project: Jackrabbit Oak
Issue Type: Bug
Components: core
Affects Versions: 1.5.4
Reporter: Stefan Egli
[CommitRateLimiter.delay|https://github.com/apache/jackrabbit-oak/blob/jackrabbit-oak-1.5.4/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation/CommitRateLimiter.java#L81]
has a race-condition when the queue length drops below thres-hold right when
{{delay()}} is called. Consider the following steps:
* thread T1 enters {{delay()}} with a positive value for {{delay}} but gets
paused right after the check for {{delay>0}}
* thread T2 enters {{setDelay(0)}}, thus goes into the synchronized block and
does a notifyAll
* thread T1 continues in {{delay()}} after above mentioned check, thus now goes
into the synchronized block - at this stage {{delay}} is {{0}} (as it's
volatile) - thus it sets {{dt=0}}.
* thread T1 then goes and calls {{wait(0)}} - which is an infinite wait, until
it gets notified. This can be forever if the threshold is never ever hit again.
Would suggest to do a {{while}} loop rather than a {{do-while}}
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