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java threads implementation in linux
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mira
Greenhorn
Joined: Mar 15, 2004
Posts: 2
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Iam using Red Hat Linux 7.3 and j2sdk 1.4.2_03 in my system.
I executed the below java program.
My java code:
public class chkprg
{
public static void main(String args[])
{
try
{
Thread.currentThread().sleep(2000);
System.out.println("some string");
}catch(Exception e){}
}
}
while executing this code,i checked the number of java processes using ps command.It showed me eight for about 2 seconds and then to zero after the program quits by printing "some string".
If iam correct,In native thread implementation,each thread is showed as a separate process in the process table.
Then why is it spawning eight processes for just a single main thread? 
I tried with some other versions of java(jdk 1.4.0 and 1.4.1_07).I got the same results.
can somebody clear my doubt?
I need a solution immediately please.
thanks in advance
regards
mira.
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Ernest Friedman-Hill
author and iconoclast
Marshal
Joined: Jul 08, 2003
Posts: 24057
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Hi Mira,
Welcome to JavaRanch!
We don't have too many rules round these parts, but we do have our naming policy, which requires that your display name not be a fictitious name. Pleae head over here and update yours, pronto. Thanks, pardner!
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[Jess in Action][AskingGoodQuestions]
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Ernest Friedman-Hill
author and iconoclast
Marshal
Joined: Jul 08, 2003
Posts: 24057
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This is a good question. Run your program, hold down "Control" and press "\" (backslash). You'll get a stack dump like the one shown below.
This stack dump shows you what's going on in every thread running in the JVM. As you can see, there are a whole bunch of them -- not just the one where your code runs, but a thread dedicated to handling UNIX signals, two threads related to garbage collection, and three threads performing internal VM tasks, for a total of seven threads. If you use ps -H to see the ASCII-art "process forest", you'll see that of the eight, one is the parent, and the other seven are the children, as listed in the thread dump.
By the way, a tip: note that sleep() is a static method that can only be used to make the calling thread go to sleep; therefore, you can (and should) simply call it as "Thread.sleep()", without invoking "currentThread()."
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subject: java threads implementation in linux
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