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  1. OpenJPA
  2. OPENJPA-2693

slices hangs by another slice db execute

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    Details

    • Type: Bug
    • Status: Open
    • Priority: Critical
    • Resolution: Unresolved
    • Affects Version/s: 2.4.0
    • Fix Version/s: None
    • Component/s: kernel, slice
    • Labels:
      None
    • Environment:
      jdk1.7,win10,tomcat7.0

      Description

      i'm using openjpa-all-2.4.0 as my orm and slice solution.here is the scenario:
      two clients send http request to our backend api server.cient A's request was doing some crud operation on db named 'pos' on a seprate mysql host instance(ip1),client B's request was doing some report query and calculation on db named 'pos' on an another seprate mysql host(ip2) instance.
      and request A was sended later than request B about 1 min,but requst B was spending lot time about 10 min,during this 10 min,request A was totally hanging there,until request A finished its job.

      so i debuged into the openjpa code ,found something:
      1 every brokerimpl is created from a template instance in Class BrokerValue:
      public Object newInstance(String clsName, Class type, Configuration conf,
      boolean fatal) {
      getTemplateBroker(clsName, type, conf, fatal);

      try

      { return _templateBroker.clone(); }

      catch (CloneNotSupportedException e)

      { throw new InternalException(e); }

      }

      the code "_templateBroker.clone()" makes every single DistributedBrokerimpl instance have a "_lock" prop point to the same instance (ReentrantSliceLock _lock).

      then when do db operation like crud,the code get into DistributedQueryImpl.execute() method,in this method it invokes broker.beginOperation(true);

      public boolean beginOperation(boolean syncTrans) {
      lock();
      try

      { assertOpen(); if (syncTrans && _operationCount == 0 && _syncManaged && (_flags & FLAG_ACTIVE) == 0) syncWithManagedTransaction(); return _operationCount++ == 1; }

      catch (OpenJPAException ke)

      { unlock(); throw ke; }

      catch (RuntimeException re)

      { unlock(); throw new GeneralException(re); }

      }

      the lock() method in this beginOperation() is using the _lock prop of DistributedBrokerImpl instance that cloned from the template instance,
      so every other thread will be blocked if there is a thread already call the lock() method in beginoperation().

      this is the root cause in my scenario.

      my quesion is : "_templateBroker.clone()" makes every DistributedBrokerImpl instance have a same "_lock" prop ,is it a bug or is there some intention for this use?

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            • Assignee:
              Unassigned
              Reporter:
              haroldjiang harold
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              Dates

              • Created:
                Updated: