On 05/11/06, Yahav Biran <[EMAIL PROTECTED]> wrote:
Another question: it looks that the java processes are spawned to
many java
processes, how one can monitor it.
I tried to top the processes and then use ps -H but the process is
disappearing until I catch it.
Java uses lots of threads - for a start the Garbage Collector (GC) runs in
its own thread. And that's even before you start writing real Java programs
which are encouraged by the language to use multi-threading.
What kernel version are you using?
[Yahav Biran] 2.6.9-22.0.2
In LinuxThreads (up to 2.4) each thread has its own PID (actually it's an
ugly hack using the internal mechanisms of fork(2) but leaving the virtual
memory shared among the "kids", somewhat reminiscent of BSD's vfork(2)),
under 2.6 and its support for proper POSIX threads, all threads appear to
belong to the same process (have the same PID) and will only be displayed by
ps(1) using -L (for instance), showing the LWP (Light Weight Process). They
are listed under /proc/<pid>/task/<tid>. That (better thread support) is one
of the best reasons to upgrade to 2.6 if you can and haven't done this yet,
IMNSHO.
If these threads appear and disappear too quickly then maybe there is a
place for tuning here - by means of controlling the thread pool parameters
(if possible). There are quite a few -X "undocumented" command line options
for the Java VM which will allow you to trace thread creation and possibly
influence thread management. RTFM java(1) and dig the net.
BTW - which JVM are you using?
[Yahav Biran] 1.4.2
Try to find which type of threads it uses.
--Amos
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