[jira] Created: (TAPESTRY-2382) Possible deadlock in ExpressionCacheImpl (on _lock instance)

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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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    [ https://issues.apache.org/jira/browse/TAPESTRY-2382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12615895#action_12615895 ]

peter schröder commented on TAPESTRY-2382:
------------------------------------------

we recently updated our webapplications to 4.1.5 and had to rollback the latest release, cause the server crashes every time it got under some load.

> 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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    [ 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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     [ https://issues.apache.org/jira/browse/TAPESTRY-2382?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Marcus Schulte reassigned TAPESTRY-2382:
----------------------------------------

    Assignee: Marcus Schulte

> 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
>            Assignee: Marcus Schulte
>            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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     [ https://issues.apache.org/jira/browse/TAPESTRY-2382?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Marcus Schulte resolved TAPESTRY-2382.
--------------------------------------

    Resolution: Fixed

> 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
>            Assignee: Marcus Schulte
>            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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