You do know your code has a typo that will cause deadlocks, don't
you? See below...
[EMAIL PROTECTED] wrote:
>
> Hi,
> The synchronize call may deadlock due to thread starvation. This is present
> in all versions of java on all platforms i could test (jdk 1.1 thru 1.4b
> on win/sol/lin)
> Example code for interlock.java is as follows :
> import java.io.*;
> import java.lang.*;
> public class interlock{
> public static int test=0; // 0 - test java synchronize. 1 - test java regular
> private static boolean atomic_spinlock1=false;
> private static boolean atomic_spinlock2=false; public interlock(){}
> public static void main(String[] args) throws InterruptedException {
> log("InterlockTest : If this code completes test was a success.");
>if(args.length==1){test=Integer.valueOf(args[0]).intValue();}
> new interlock().startup();}
> public static void log(String s){ System.err.println(">"+s); }
> public static void blink(int
>i){try{Thread.currentThread().sleep(10+i);}catch(Exception
> e){}}
> public static void spinlock1_rel(){atomic_spinlock1=false;}
> public static boolean spinlock1_set(){
> if (atomic_spinlock1==false) { atomic_spinlock1=true; return true; } else
> { return false; } }
> public static void spinlock2_rel(){atomic_spinlock2=false;}
> public static boolean spinlock2_set(){
> if (atomic_spinlock2==false) { atomic_spinlock2=true; return true; } else
> { return false; } }
> public static synchronized void s_spinlock1_rel(){atomic_spinlock1=false;}
> public static synchronized boolean s_spinlock1_set(){
> if (atomic_spinlock1==false) { atomic_spinlock1=true; return true; } else
> { return false; } }
> public static synchronized void s_spinlock2_rel(){atomic_spinlock2=false;}
> public static synchronized boolean s_spinlock2_set(){
> if (atomic_spinlock2==false) { atomic_spinlock2=true; return true; } else
> { return false; } }
> private void startup() { if (test==0) {log("Testing atomic spinlocks with
> Java Virtual Machine sync.... "); }
> else {log(" Testing atomic spinlocks without Java Virtual Machine sync...");}
> Runner y=new Runner(0);Runner s=new Runner(1); y.start();blink(100);s.start();
> }
> class Runner extends Thread implements Runnable{ private int runr=0;
> Runner(int seq) { runr=seq; } public void run() { log(" Started runner "+runr+"
> -- ");
> log(runr+": Setting atomic spinlock 1...");
> if (test!=0){while(spinlock1_set()==false){}} else {
>while(s_spinlock2_set()==false){}
Note in the line above that test!=0 is setting spinlock 1 and the else
branch is setting spinlock 2. So, whenever you test the synchronized
version you are going to get a deadlock since your locking has no
thread identity... a thread can block itself by checking the lock
after setting it.
-Paul Speed
> }
> log(runr+": Set spinlock 1. Now sleeping... ");
> blink(1000); log(runr+": Finished sleeping. Now setting spinlock 2... (if
> bug exists it will hang here...) ");
> if (test!=0){while(spinlock2_set()==false){}} else { while(spinlock2_set()==false){}
> }
> log(runr+": Spinlock 2 set. Now unsetting both spinlocks... ");
> if (test!=0){spinlock2_rel(); spinlock1_rel();}else{s_spinlock2_rel();
>s_spinlock1_rel();}
> log(runr+": Completed. "); }} }
> ....
> BTW, my email has changed.
> [EMAIL PROTECTED] --> [EMAIL PROTECTED]
> Thanks.
> -Ys-
>
> Free, encrypted, secure Web-based email at www.hushmail.com
