[jboss-jira] [JBoss JIRA] (DROOLS-787) getProcessRuntimeFactoryService method of ProcessRuntimeFactory is synchronized.

[René Zanner (JIRA)]

    [ https://issues.jboss.org/browse/DROOLS-787?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13099727#comment-13099727 ] 

René Zanner commented on DROOLS-787:
------------------------------------

We have the same issue here - it dramatically reduces scalability. Even when there is no ProcessRuntimeFactoryService available, every thread is blocked by this call during creation of a StatefulKnowledgeSessionImpl...

I would suggest to statically initialize this singleton in ProcessRuntimeFactory - without any synchronization, since the static initialization of a class is synchronized automatically by the VM.

{code}
private static ProcessRuntimeFactoryService provider = initializeProvider();

private static ProcessRuntimeFactoryService initializeProvider() {
	ServiceRegistryImpl.getInstance().addDefault(ProcessRuntimeFactoryService.class,
			"org.jbpm.process.instance.ProcessRuntimeFactoryServiceImpl");
	ProcessRuntimeFactoryService service = null;
	try {
		service = ServiceRegistryImpl.getInstance().get(ProcessRuntimeFactoryService.class);
	} catch (IllegalArgumentException e) {
		LOGGER.warn(e.getMessage(), e);
	}
	return service;
}

public static InternalProcessRuntime newProcessRuntime(StatefulKnowledgeSessionImpl workingMemory) {
	if (provider == null) {
		LOGGER.warn("Could not load the ProcessRuntimeFactoryService from ServiceRegistryImpl - returning 'null'.");
		return null;
	}
	return provider.newProcessRuntime(workingMemory);
}
{code}

The only thing that's missing then is the possibility to reset and dynamically re-initialize this singleton. 
When that *really* is a requirement, then there should be implemented some state-of-the-art synchronization, i.e. Double-checked locking (as of Java 5 with the {{volatile}} keyword it's even working, see https://en.wikipedia.org/wiki/Double-checked_locking#Usage_in_Java or http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html). 
Nowadays there's really no need to synchronize the whole getter.



> getProcessRuntimeFactoryService method of ProcessRuntimeFactory is synchronized.
> --------------------------------------------------------------------------------
>
>                 Key: DROOLS-787
>                 URL: https://issues.jboss.org/browse/DROOLS-787
>             Project: Drools
>          Issue Type: Bug
>         Environment: software platform 
>            Reporter: vipul gajara
>            Assignee: Petr Široký
>
> getProcessRuntimeFactoryService is getter method of singleton class "org.drools.core.runtime.process.ProcessRuntimeFactory" but this method is static synchronized so at a time only one thread can call it .
> Due to above issue when we are using drools in multi threaded enviorenment threads are getting locked at this method and performance degrades when creating KSession objects.



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