| Summary: | ConcurrentModificationException | ||
|---|---|---|---|
| Product: | JMeter - Now in Github | Reporter: | Chris <chrispesarchick> |
| Component: | HTTP | Assignee: | JMeter issues mailing list <issues> |
| Status: | RESOLVED FIXED | ||
| Severity: | major | ||
| Priority: | P3 | ||
| Version: | 1.8 | ||
| Target Milestone: | --- | ||
| Hardware: | PC | ||
| OS: | Linux | ||
I just committed a change to org.apache.jmeter.testelement.AbstractTestElement
that changed the new HashMap() to Collections.synchronizedMap(new HashMap()). I
think this should help fix this problem, and not slow things down overly much.
It's still not perfect, since to do a synchronized map correctly, you're
supposed to manually synchronize iteration code, but since the Map is a private
variable of AbstractTestElement, this is currently possible in other classes.
One way to fix this would be to add a method to the TestElement interface, such as:
getSyncObject()
which would return the synchronized Map, so developers could write code such as:
Iterater iter = testElement.getPropertyNames().iterator();
synchronized(testElement.getSyncObject())
{
while(iter.hasNext())
{
Object item = iter.next();
//do stuff safely
}
}
It seems inelegant to me, but I'm not sure what a good alternative is. Using
Hashtable is not viable, since Map's can hold null values, and Hashtables can't,
and JMeter saves null values.
I retried this with 1.8.1 and the problem is still there. This issue has been migrated to GitHub: https://github.com/apache/jmeter/issues/1023 |
The problem seems to be the HashTree which is a HashMap. This is a major problem when there are multiple threads and the script is large. If a thread should get this error then the thread is done. Then the test will not be correct. I tried a few things. I tried synchronizing on the HashTree in TestCompiler, but that didn't work. I then went to 'public void traverse(HashTreeTraverser visitor)' in HashTree. I tried synchronizing on list() and visitor that didn't work. Then I created a static object and synchronized the object and that has been working. This slows down the performance of setting up the test before it executes the test script. Since I don't have a full understanding of the program, my guess there is a better place. If anybody has another suggestion, let me know and I will give it a try. This happens on NT and Linux. java.util.ConcurrentModificationException at java.util.HashMap$HashIterator.nextEntry(HashMap.java:750) at java.util.HashMap$KeyIterator.next(HashMap.java:786) at org.apache.jmeter.threads.TestCompiler.hasFunctions(TestCompiler.java:498) at org.apache.jmeter.threads.TestCompiler.saveSamplerConfigs(TestCompiler.java: 196) at org.apache.jmeter.threads.TestCompiler.subtractNode(TestCompiler.java:158) at org.apache.jorphan.collections.HashTree.traverseInto(HashTree.java:908) at org.apache.jorphan.collections.HashTree.traverseInto(HashTree.java:902) at org.apache.jorphan.collections.HashTree.traverseInto(HashTree.java:902) at org.apache.jorphan.collections.HashTree.traverseInto(HashTree.java:902) at org.apache.jorphan.collections.HashTree.traverse(HashTree.java:886) at org.apache.jmeter.threads.JMeterThread.run(JMeterThread.java:125) at java.lang.Thread.run(Thread.java:536)