[CXF-6629] ConcurrentModificationException at AbstractResourceInfo.clearProxies()

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.1.2
• Fix Version/s: 3.0.7, 3.1.4
• Component/s: JAX-RS
• Labels: cxf-rt-frontend-jaxrs

Environment

Redhat Enterprise Linux 6, Java 8, Tomcat 8
cxf-rt-frontend-jaxrs 3.1.2
cxf-rt-rs-client 3.1.2

• Estimated Complexity: Unknown
• Assignee: Sergey Beryozkin
• Reporter: Chester Kim
• Created: 07/Oct/15 18:32
• Updated: 14/Oct/16 14:12
• Resolved: 08/Oct/15 09:45

Description

Occasionally, concurrentmodification exception happens in AbstractResourceInfo. Following's a peek of stack trace

java.util.ConcurrentModificationException at java.util.WeakHashMap$HashIterator.nextEntry(WeakHashMap.java:806) at java.util.WeakHashMap$ValueIterator.next(WeakHashMap.java:833) at org.apache.cxf.jaxrs.model.AbstractResourceInfo.clearProxies(AbstractResourceInfo.java:355) at org.apache.cxf.jaxrs.model.AbstractResourceInfo.clearThreadLocalProxies(AbstractResourceInfo.java:346) at org.apache.cxf.jaxrs.provider.ProviderFactory.clearProxies(ProviderFactory.java:745) at org.apache.cxf.jaxrs.provider.ProviderFactory.clearThreadLocalProxies(ProviderFactory.java:738) at org.apache.cxf.jaxrs.client.WebClient.handleResponse(WebClient.java:1195) at org.apache.cxf.jaxrs.client.WebClient.doResponse(WebClient.java:1156) at org.apache.cxf.jaxrs.client.WebClient.doChainedInvocation(WebClient.java:1092) at org.apache.cxf.jaxrs.client.WebClient.doInvoke(WebClient.java:894) at org.apache.cxf.jaxrs.client.WebClient.doInvoke(WebClient.java:865) at org.apache.cxf.jaxrs.client.WebClient.invoke(WebClient.java:428) at org.apache.cxf.jaxrs.client.WebClient$SyncInvokerImpl.method(WebClient.java:1621) at org.apache.cxf.jaxrs.client.WebClient$SyncInvokerImpl.method(WebClient.java:1616) at org.apache.cxf.jaxrs.client.WebClient$SyncInvokerImpl.get(WebClient.java:1536) at org.apache.cxf.jaxrs.client.spec.InvocationBuilderImpl.get(InvocationBuilderImpl.java:80) at 
...

I noticed the codes around exception(AbstractResourceInfo:346) is as following (tlp.remove())

    private <T> void clearProxies(Map<Class<?>, Map<T, ThreadLocalProxy<?>>> tlps) {
        Map<T, ThreadLocalProxy<?>> proxies = tlps == null ? null : tlps.get(getServiceClass());
        if (proxies == null) {
            return;
        }
        for (ThreadLocalProxy<?> tlp : proxies.values()) {
            if (tlp != null) {
                tlp.remove();
            }
        }
    }

I don't think it's good idea to remove threadlocal value while iterating the list.