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Posted to dev@tapestry.apache.org by "Marcus Schulte (JIRA)" <de...@tapestry.apache.org> on 2008/08/03 19:11:44 UTC
[jira] Commented: (TAPESTRY-2382) Possible deadlock in
ExpressionCacheImpl (on _lock instance)
[ https://issues.apache.org/jira/browse/TAPESTRY-2382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12619351#action_12619351 ]
Marcus Schulte commented on TAPESTRY-2382:
------------------------------------------
I've supplied an exploratory patch-jar for TAPESTRY-2530 which should also affect this issue (hopefully positively). I would be very grateful if anybody experiencing this problem could try it out. It's just a matter of the jar being dropped into WEB-INF/lib.
> Possible deadlock in ExpressionCacheImpl (on _lock instance)
> ------------------------------------------------------------
>
> Key: TAPESTRY-2382
> URL: https://issues.apache.org/jira/browse/TAPESTRY-2382
> Project: Tapestry
> Issue Type: Bug
> Components: Framework
> Affects Versions: 4.1.3
> Reporter: Alexander Gavrilov
> Priority: Critical
> Fix For: 4.1.6
>
>
> Under some circumstances deadlock occurs in the ExpressionCacheImpl.
> 1)Thread Ta opening a Page Pa. Page Pa does not bound to the current request cycle, so new Instance requested from PageSource and current thread enter to the synchronized _pool.borrowObject(key)
> 2) At this time thread Tb render page Pb, and for some property evaluates expression binding. So ExpressionCacheImpl's _lock locked by thread Tb. Result of expression evaluation is a reference to the Page Pc instance, which is not bound to the current thread, so new Instance requested from PageSource and current thread tried to enter to the synchronized _pool.borrowObject(key) which is locked by Ta.
> 3) Thread Ta worked creating new Page Pa Instance, which is not exists in the pool, so a new Page instance should be created. In the proccess of parsing page loader try to evaluate expression binding and try to lock a ExpressionCacheImpl's _lock, which is locked by thread Tb.
> 4) Whe have a deadlock, so no new page instance and expression could be created and evaluated.
> This causes a serios problems while system startup, so we need to restart our app many times, untill it warmed up.
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