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From Pinaki Poddar <ppod...@apache.org>
Subject Re: multithreaded, read/write?
Date Wed, 17 Dec 2008 15:29:08 GMT

Hi Fernando,
  Can you please pick up revision 727297 [1] and see if that works for your
prototype/test harness?
The changes are:
  a) slice queries minimize lookup to their shared context for isUnique() by
caching the unique flag. This reduces one source of thread deadlock
  b) StateManagers use their own instance-level lock rather than locking the
broker for everything. This reduces another source of thread deadlock. But
this is a riskier change (though it did not show up any regression on
OpenJPA test corpus). I am trying to find out why, at the first place,
StateManagers were using the global Broker's lock.
  c) all slice queries run in parallel

  I have noted that Slice should *always* run with
openjpa.Multithreaded=true. If these changes (and similar ones but in the
same direction -- rather than overhauling the threading model of the kernel)
alleviate the deadlock while retaining the parallel execution at per-Slice
level -- then I will change Slice configuration to enforce
openjpa.Multithreaded=true.

[1]
http://n2.nabble.com/svn-commit%3A-r727297---in--openjpa-trunk%3A-openjpa-jdbc-src-main-java-org-apache-openjpa-jdbc-kernel--openjpa-kernel-src-main-java-org-apache-openjpa-kernel--openjpa-slice-src-main-java-org-apache-o-td1666666.html


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