If you have a Java application that is consuming CPU when it isn't doing anything, how do you determine what it is doing?

Question

I am calling a vendor\'s Java API, and on some servers it appears that the JVM goes into a low priority polling loop after logging into the API (CPU at 100% usage). The sam

Answer 1

JRockit Mission Control Latency Analyzer.

The Latency Analyzer that comes with JRockit shows you what the JVM is "doing" when it's not doing anything. In the latest version you can see latencies for:

• Java wait/blocked/sleep/parked.
• File I/O
• Network I/O
• Memory allocation
• GC pauses
• JVM latencies, e.g code generation and class loading
• Thread suspension

The tool will give you the stack trace when the latency occurred. You can view the latency data in many different ways (aggregated traces, as a histogram, in a thread graph etc.). The tool also allows you to see transitions between threads, for instance when one thread notifies another.

latency analyzer http://blogs.oracle.com/hirt/WindowsLiveWriter/The.0LatencyAnalyserMigratedfromtheoldBE_7246/latency_graph_2.png

The overhead is negligible and unlike many other tools it can be used in a production environment. This blog post gives you a brief introduction and the program can be downloaded here.

It's free to use for development!