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https://issues.jboss.org/browse/JBSEAM-4861?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ahus1 updated JBSEAM-4861:
--------------------------
Forum Reference:
http://www.seamframework.org/Community/GlobalFactoryLockInComponentjavaPerformanceIssue
> Component.java uses application wide factoryLock too often
> -----------------------------------------------------------
>
> Key: JBSEAM-4861
> URL: https://issues.jboss.org/browse/JBSEAM-4861
> Project: Seam 2
> Issue Type: Patch
> Components: Core
> Affects Versions: 2.2.2.Final, 2.3.0.ALPHA
> Reporter: ahus1
> Attachments: Component.patch, Component.patch, Component.patch
>
>
> Whenever getInstanceFromFactory() is called and a factory is used, a
> (application wide) lock is used: factoryLock.
> In my environments the Factory uses expensive calls to the backend to create
> an object, and during this time no other Factory method is allowed to be
> called. This is a severe bottleneck in a multiuser environment.
> This lock is important for APPLICATION scoped components, but other
> components that are i.e. CONVERSATION scoped, Seam already ensures that only
> one Thread has access to the current conversation. The same should be true
> for PAGE and EVENT. In this cases no lock should be acquired. UPDATE:
> Factories that use injection should not be called multithreaded, therefore an
> updated condition.
> See the follwing code snippet. I also attach a patch.
> I tested the patch for Seam 2.2.2.Final - I would be most happy to have this
> included in 2.2 and 2.3 branch.
> Br Alexander.
> {code:title=Component.java}
> ScopeType scopeResult = getOutScope(factoryMethod.getScope(),
> factoryMethod.getComponent());
> ScopeType scopeFactory = factoryMethod.getComponent().getScope();
> boolean lockingNeeded = false;
> /*
> * we need this lock in the following cases: (1) the target scope is
> * accessed by more than one thread (as we don't want to create the
> same
> * object by two threads at the same time for the same scope) OR (2)
> the
> * factory is accessed by more than one thread and is using
> interceptors
> * (as accessing a factory multiple times might mess up interceptors).
> * This assumes that (1) the scopes CONVERSATION, EVENT and PAGE can't
> * be accessed by more than one thread anyway due to CONVERSATION
> being
> * locked for the current thread anyway, and EVENT and PAGE being only
> * short-lived anyway. (2) a factory that doesn't use injection can be
> * accessed multi threaded. See JBSEAM-4669/JBSEAM-2419 for the
> original
> * discussion.
> */
> if ((scopeResult != ScopeType.CONVERSATION
> && scopeResult != ScopeType.EVENT && scopeResult !=
> ScopeType.PAGE)
> || (scopeFactory != ScopeType.CONVERSATION
> && scopeFactory != ScopeType.EVENT
> && scopeFactory != ScopeType.PAGE && factoryMethod
> .getComponent().interceptionEnabled)) {
> lockingNeeded = true;
> }
> if (lockingNeeded) {
> /*
> * synchronize only on the factory instance, let the rest of the
> world
> * continue.
> */
> synchronized (factory) {
> return createInstanceFromFactory(name, scope, factoryMethod,
> factory);
> }
> } else {
> return createInstanceFromFactory(name, scope, factoryMethod,
> factory);
> }
> [...]
> private static Object createInstanceFromFactory(String name, ScopeType
> scope,
> Init.FactoryMethod factoryMethod, Object factory) {
> // check whether there has been created an instance by another thread
> // while waiting for this function's lock
> if (scope != STATELESS) {
> Object value = (scope == null) ? Contexts.lookupInStatefulContexts(name)
> : scope.getContext().get(name);
> if (value != null) {
> return value;
> }
> }
>
> if (factory == null) {
> return null;
> } else {
> Object result =
> factoryMethod.getComponent().callComponentMethod(factory,
> factoryMethod.getMethod());
> return handleFactoryMethodResult(name, factoryMethod.getComponent(),
> result, factoryMethod.getScope());
> }
> }
> {code}
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