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JDK1.3 100% CPU. Total hangup.

 
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Our environemt is HP-UX with 4 CPU, 2.5Gb of memory. Java is 1.3.1_13 (latest release). All necessary Unix patches installed.
We perform a load test over our application server with 40 users only. The test is pretty simple and doesn't deserve to be explained here (it uses no special system resources). In an unpredictable moment the java process utilizes 100% CPU and doesn't react to 'kill -3' but to 'kill -9' only. The problem is it happens whenever it wishes. No logic behind it. Every test loop takes about 1 minute to complete and the server gets stucked sometimes after 10 mins and sometimes after 3 houres of work. Changing java heap parameters and playing with new/old generation ratio also doesn't lead to any conclusion. Sometimes it happens before full gc but other settings allow full gc to happen every minute and the server works for hours.

What can it be? Any ideas? Any directions of investingation the problem?
 
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got an eternal loop somewhere?
 
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"Kill -3" should give you a thread dump - does it? - which will tell you a lot about which threads are running, which are blocked, and so on, complete with stack traces. Beyond that, a profiler (or debugger) would be incredibly useful in this case.

- Peter
 
Roman Rytov
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well, as I wrote the process doesn't react to _any_ signal except for kill -9, that kills it absolutelly.

Can it be a code that leads to such a situation or I may absolutelly blame the system and JDK libraries?
 
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You need more information, good trace logging would help here but, only so much. The best is if you could run it with a profiler and see exactly what is spinning off into space.
 
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