Problem with JMX query of Coherence node MBeans visible in JConsole
- by Quinn Taylor
I'm using JMX to build a custom tool for monitoring remote Coherence clusters at work. I'm able to connect just fine and query MBeans directly, and I've acquired nearly all the information I need. However, I've run into a snag when trying to query MBeans for specific caches within a cluster, which is where I can find stats about total number of gets/puts, average time for each, etc.
The MBeans I'm trying to access programatically are visible when I connect to the remote process using JConsole, and have names like this:
Coherence:type=Cache,service=SequenceQueue,name=SEQ%GENERATOR,nodeId=1,tier=back
It would make it more flexible if I can dynamically grab all type=Cache MBeans for a particular node ID without specifying all the caches. I'm trying to query them like this:
QueryExp specifiedNodeId = Query.eq(Query.attr("nodeId"), Query.value(nodeId));
QueryExp typeIsCache = Query.eq(Query.attr("type"), Query.value("Cache"));
QueryExp cacheNodes = Query.and(specifiedNodeId, typeIsCache);
ObjectName coherence = new ObjectName("Coherence:*");
Set<ObjectName> cacheMBeans = mBeanServer.queryMBeans(coherence, cacheNodes);
However, regardless of whether I use queryMBeans() or queryNames(), the query returns a Set containing...
...0 objects if I pass the arguments shown above
...0 objects if I pass null for the first argument
...all MBeans in the Coherence:* domain (112) if I pass null for the second argument
...every single MBean (128) if I pass null for both arguments
The first two results are the unexpected ones, and suggest a problem in the QueryExp I'm passing, but I can't figure out what the problem is. I even tried just passing typeIsCache or specifiedNodeId for the second parameter (with either coherence or null as the first parameter) and I always get 0 results.
I'm pretty green with JMX — any insight on what the problem is? (FYI, the monitoring tool will be run on Java 5, so things like JMX 2.0 won't help me at this point.)
