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Groups > comp.lang.java.programmer > #32881

Re: The code being executed before hitting main() method

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This is my Java class:

public class Hello {
    public static void main(final String[] args){
        final String str = "Hello World";

        System.out.println(str);

        System.out.println("No. of active thread: " + Thread.activeCount());

        try {
            Thread.sleep(4000000); //let the 'java' process run for long time so i can run command 'jstack'
        }
        catch(final Exception e){
            System.out.println(e);
        }
    }
}
Run:
java Hello &
Then by running 'ps' command, I found the process id of 'java' -- which is 2554 on my hand, then run:
$jstack 2554
2015-10-14 11:27:55
Full thread dump Java HotSpot(TM) Server VM (24.71-b01 mixed mode):

"Attach Listener" daemon prio=10 tid=0x6c100800 nid=0xb05 waiting on condition [0x00000000]
   java.lang.Thread.State: RUNNABLE

"Service Thread" daemon prio=10 tid=0x6c68a400 nid=0xa0b runnable [0x00000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread1" daemon prio=10 tid=0x6c688800 nid=0xa0a waiting on condition [0x00000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread0" daemon prio=10 tid=0x6c686800 nid=0xa09 waiting on condition [0x00000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" daemon prio=10 tid=0x6c684c00 nid=0xa07 runnable [0x00000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" daemon prio=10 tid=0x6c674800 nid=0xa06 in Object.wait() [0x6fb7d000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x9efc4240> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:135)
        - locked <0x9efc4240> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:151)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:209)

"Reference Handler" daemon prio=10 tid=0x6c673000 nid=0xa05 in Object.wait() [0x6fd7d000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x9efc3ed8> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:503)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:133)
        - locked <0x9efc3ed8> (a java.lang.ref.Reference$Lock)

"main" prio=10 tid=0xb7607400 nid=0x9fb waiting on condition [0xb7752000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
        at java.lang.Thread.sleep(Native Method)
        at temp.Hello.main(Hello.java:16)

"VM Thread" prio=10 tid=0x6c670800 nid=0xa04 runnable 

"GC task thread#0 (ParallelGC)" prio=10 tid=0xb7611400 nid=0x9fc runnable 

"GC task thread#1 (ParallelGC)" prio=10 tid=0xb7612800 nid=0x9fd runnable 

"GC task thread#2 (ParallelGC)" prio=10 tid=0xb7614000 nid=0x9fe runnable 

"GC task thread#3 (ParallelGC)" prio=10 tid=0xb7615800 nid=0x9ff runnable 

"GC task thread#4 (ParallelGC)" prio=10 tid=0xb7617000 nid=0xa00 runnable 

"GC task thread#5 (ParallelGC)" prio=10 tid=0xb7618400 nid=0xa01 runnable 

"GC task thread#6 (ParallelGC)" prio=10 tid=0xb7619c00 nid=0xa02 runnable 

"GC task thread#7 (ParallelGC)" prio=10 tid=0xb761b400 nid=0xa03 runnable 

"VM Periodic Task Thread" prio=10 tid=0x6c68c400 nid=0xa0c waiting on condition 

JNI global references: 106

Wow, so many threads! So many garbage collection threads for such a simple program! I am even wondering if the 'java' on this RedHat Linux needs to be configured.

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Thread

The code being executed before hitting main() method John <xsli2@yahoo.com> - 2015-10-14 06:26 -0700
  Re: The code being executed before hitting main() method Eric Douglas <e.d.programmer@gmail.com> - 2015-10-14 06:51 -0700
    Re: The code being executed before hitting main() method Thomas Richter <thor@math.tu-berlin.de> - 2015-10-14 16:31 +0200
      Re: The code being executed before hitting main() method Eric Douglas <e.d.programmer@gmail.com> - 2015-10-14 08:54 -0700
        Re: The code being executed before hitting main() method Thomas Richter <thor@math.tu-berlin.de> - 2015-10-14 18:04 +0200
          Re: The code being executed before hitting main() method j4n bur53 <janburse@fastmail.fm> - 2015-10-14 18:49 +0200
  Re: The code being executed before hitting main() method John <xsli2@yahoo.com> - 2015-10-14 08:19 -0700
    Re: The code being executed before hitting main() method John <xsli2@yahoo.com> - 2015-10-14 10:04 -0700
    Re: The code being executed before hitting main() method j4n bur53 <janburse@fastmail.fm> - 2015-10-14 19:08 +0200

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