Details
Critical 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
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?