Multiple instances of java class

[Neo Snyder]

I have written a simple java program test.java
import java.io.*;
public class test{
public static void main(String args[]){
while(true){
System.out.println("hello");
}
}
}
when i run this program using the command
java test& , 10 instances of this program is shown in the process listing.Iam working in linux

[Dirk Schreckmann]

Welcome to JavaRanch, Noe!
On Windows XP Professional, the task manager shows only one JAVA.EXE process (using about 5MB of memory and very little CPU time).
[ April 01, 2003: Message edited by: Dirk Schreckmann ]

[Cindy Glass]

java test&
Not sure what this does in Linux, but if that is a wildcard then perhaps you are invoking multiple programs.
The "correct" syntax is
>java test
which should only start one JVM using one process.

[Layne Lund]

In *nix, the & after a command detatches the newly created process from the terminal. This allows you to continue typing other commands on the command line while the program continues to run in the background.
How do you see that 10 instances of it are running? If you use the "ps" or "top" commands it should only list a signle instance. However, I haven't tried it myself. You have definitely piqued my curiosity. I'll have to check this out when I have a chance at home this evening.
Layne

[Eddy Chang]

On linux.

$java -version

java version "1.3.1_02"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.1_02-b02)
Java HotSpot(TM) Client VM (build 1.3.1_02-b02, mixed mode)

$java test &
The other java processes listed are child threads spawned by the jvm.

$ps auxwwf | grep echang

echang    5257 99.9  1.3 170788 7080 pts/3   R    02:05   1:48  \_ /usr/java/jdk1.3.1_02/bin/i386/native_threads/java test
echang    5284  0.0  1.3 170788 7080 pts/3   S    02:05   0:00  |   \_ /usr/java/jdk1.3.1_02/bin/i386/native_threads/java test
echang    5285  0.0  1.3 170788 7080 pts/3   S    02:05   0:00  |       \_ /usr/java/jdk1.3.1_02/bin/i386/native_threads/java test
echang    5286  0.0  1.3 170788 7080 pts/3   S    02:05   0:00  |       \_ /usr/java/jdk1.3.1_02/bin/i386/native_threads/java test
echang    5287  0.0  1.3 170788 7080 pts/3   S    02:05   0:00  |       \_ /usr/java/jdk1.3.1_02/bin/i386/native_threads/java test
echang    5288  0.1  1.3 170788 7080 pts/3   S    02:05   0:00  |       \_ /usr/java/jdk1.3.1_02/bin/i386/native_threads/java test
echang    5289  0.0  1.3 170788 7080 pts/3   S    02:05   0:00  |       \_ /usr/java/jdk1.3.1_02/bin/i386/native_threads/java test
echang    5290  0.0  1.3 170788 7080 pts/3   S    02:05   0:00  |       \_ /usr/java/jdk1.3.1_02/bin/i386/native_threads/java test
echang    5291  0.0  1.3 170788 7080 pts/3   S    02:05   0:00  |       \_ /usr/java/jdk1.3.1_02/bin/i386/native_threads/java test

What are the other threads? The ones listed in the thread dump.
$kill -QUIT 5257

Full thread dump:
"Signal Dispatcher" daemon prio=1 tid=0x497077e0 nid=0x14aa waiting on monitor [0..0]
"Finalizer" daemon prio=1 tid=0x49700608 nid=0x14a7 waiting on monitor [0xbf3ff000..0xbf3ff890]
        at java.lang.Object.wait(Native Method)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:108)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:123)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:162)
"Reference Handler" daemon prio=1 tid=0x808e498 nid=0x14a6 waiting on monitor [0xbf5ff000..0xbf5ff890]
        at java.lang.Object.wait(Native Method)
        at java.lang.Object.wait(Object.java:420)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:110)
"main" prio=1 tid=0x804e818 nid=0x1489 runnable [0xbfffd000..0xbfffd334]
        at test.main(test.java:3)
"VM Thread" prio=1 tid=0x808b3c0 nid=0x14a5 runnable
"VM Periodic Task Thread" prio=1 tid=0x49706568 nid=0x14a8 waiting on monitor
"Suspend Checker Thread" prio=1 tid=0x49706e98 nid=0x14a9 runnable

[ April 07, 2003: Message edited by: Eddy Chang ]