[CXF-3558] JaxWsProxyFactoryBean.create is not thread-safe

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4
• Fix Version/s: 2.4.1, 2.3.5
• Component/s: JAX-WS Runtime
• Estimated Complexity: Moderate
• Assignee: Freeman Yue Fang
• Reporter: Tomasz Nurkiewicz
• Created: 30/May/11 20:00
• Updated: 08/Aug/11 14:43
• Resolved: 31/May/11 09:59

Description

While running JaxWsProxyFactoryBean.create concurrently I encountered the following exception:

Caused by: java.util.ConcurrentModificationException
	at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:761)
	at java.util.LinkedList$ListItr.next(LinkedList.java:696)
	at org.apache.cxf.service.factory.AbstractServiceFactoryBean.sendEvent(AbstractServiceFactoryBean.java:71)
	at org.apache.cxf.service.factory.ReflectionServiceFactoryBean.create(ReflectionServiceFactoryBean.java:238)
	at org.apache.cxf.jaxws.support.JaxWsServiceFactoryBean.create(JaxWsServiceFactoryBean.java:202)
	at org.apache.cxf.frontend.AbstractWSDLBasedEndpointFactory.createEndpoint(AbstractWSDLBasedEndpointFactory.java:101)
	at org.apache.cxf.frontend.ClientFactoryBean.create(ClientFactoryBean.java:90)
	at org.apache.cxf.frontend.ClientProxyFactoryBean.create(ClientProxyFactoryBean.java:152)
	at org.apache.cxf.jaxws.JaxWsProxyFactoryBean.create(JaxWsProxyFactoryBean.java:142)

Although not documented , org.apache.cxf.service.factory.ReflectionServiceFactoryBean#create called somewhere during endpoint creation is synchronized which suggests whole create is thread-safe, but apparently it's not.

I managed to discover source of this problem. I captured two threads: one (pool-1-thread-4) entered synchronized ReflectionServiceFactoryBean#create, the second one (pool-1-thread-2) didn't made there yet but instead it calls AbstractServiceFactoryBean.setBus outside of the synchronized block. This causes the org.apache.cxf.service.factory.AbstractServiceFactoryBean#listeners to be updated, making the former thread being susceptible to ConcurrentModificationException. Stack dumps attached.

Please either fix concurrency issue (making listeners instance of java.util.concurrent.CopyOnWriteArrayList might not be enough though) or document that JaxWsProxyFactoryBean.create is not thread-safe.