Hi
When doing some load testing on FtpServer, I ran into a threading
issue in MdcInjectionFilter. When adding some load, I frequently get a
ConcurrentModificationException on removing the MDC properties. Here's
the stacktrace:
java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
at java.util.HashMap$KeyIterator.next(HashMap.java:828)
at
org.apache.mina.filter.logging.MdcInjectionFilter.filter(MdcInjectionFilter.java:140)
at
org.apache.mina.filter.util.CommonEventFilter.messageReceived(CommonEventFilter.java:67)
at
org.apache.mina.common.DefaultIoFilterChain.callNextMessageReceived(DefaultIoFilterChain.java:401)
at
org.apache.mina.common.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:38)
at
org.apache.mina.common.DefaultIoFilterChain$EntryImpl$1.messageReceived(DefaultIoFilterChain.java:820)
at
org.apache.mina.common.DefaultIoFilterChain$HeadFilter.messageReceived(DefaultIoFilterChain.java:604)
at
org.apache.mina.common.DefaultIoFilterChain.callNextMessageReceived(DefaultIoFilterChain.java:401)
at
org.apache.mina.common.DefaultIoFilterChain.fireMessageReceived(DefaultIoFilterChain.java:395)
at
org.apache.mina.common.AbstractPollingIoProcessor.read(AbstractPollingIoProcessor.java:425)
at
org.apache.mina.common.AbstractPollingIoProcessor.process(AbstractPollingIoProcessor.java:387)
at
org.apache.mina.common.AbstractPollingIoProcessor.process(AbstractPollingIoProcessor.java:379)
at
org.apache.mina.common.AbstractPollingIoProcessor.access$400(AbstractPollingIoProcessor.java:43)
at
org.apache.mina.common.AbstractPollingIoProcessor$Worker.run(AbstractPollingIoProcessor.java:676)
at
org.apache.mina.util.NamePreservingRunnable.run(NamePreservingRunnable.java:51)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)
The cause of the problem is a call to setProperty() from
org.apache.ftpserver.command.USER. I'm not familiar enough with the
MDC filter to identify the culprit. Simply synchronizing the context
Map does not help. The test I'm running is quite simple:
package org.apache.ftpserver.clienttests;
public class MdcThreadingTest extends ClientTestTemplate {
public void testLoginMulti() throws Exception {
tearDown();
for(int i = 0; i<10000; i++) {
setUp();
assertTrue(client.login(ADMIN_USERNAME,
ADMIN_PASSWORD));
tearDown();
}
System.out.println("All done!");
}
}
Any help would be appreciated!
/niklas
