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  1. Tapestry
  2. TAPESTRY-2382

Possible deadlock in ExpressionCacheImpl (on _lock instance)


    • Type: Bug
    • Status: Resolved
    • Priority: Critical
    • Resolution: Fixed
    • Affects Version/s: 4.1.3
    • Fix Version/s: 4.1.6
    • Component/s: Framework
    • Labels:


      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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              • Assignee:
                mschu Marcus Schulte
                lucker Alexander Gavrilov
              • Votes:
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                • Created: