Remove locks of type Object to help lock contention analysis

[Sean Chou]

Hi,
   I found there are code pieces using java.lang.Object as a lock type. It
appears as follow:

*//example
...
private Object lock = new Object();
...
public void foo() {
synchronized(lock) { ... }
...
//end of example*

   This will give some confusing results when using tools like JLM to
analyze
synchronization contention, because tools usually use class name of the lock

instance to indicate the lock. Here is an example from JLM:
*
**//example2
%MISS GETS NONREC SLOW REC TIER2 TIER3 %UTIL AVER-HTM MON-NAME
100 562 562 562 0 0 0 0 3377 [32C7C768] java/lang/Object at 9559CA00 (Object)
100 562 562 562 0 0 0 0 3160 [32C7C3D0] java/lang/Object at 951DA530 (Object)
// <=  which lock is this one representing?
100 560 560 560 0 0 0 0 3155 [37B4E854] java/lang/Object at 94BA1C00 (Object)
100 58 58 58 0 0 0 0 3100 [355D3AB8]
org/apache/derby/impl/services/daemon/BasicDaemon at 9DE5B348 (Object)
100 28 28 28 0 0 0 0 3892 [355D401C]
com/ibm/ws/sib/msgstore/persistence/lock/DBLockManagerThread at 9F6E5D18(Object)
//end of example2*

   The first three lines indicate three locks of type java.lang.Object, and
it is impossible to distinguish them.

   If these locks are changed to a named type as follows,

//example3
*...
private class InterruptLock {}
private Object lock = new InterruptLock();
...
public void foo() {
synchronized(lock) { ... } }
...*
//end of example3

   Exaple2 would be like this:

//example4
*%MISS GETS NONREC SLOW REC TIER2 TIER3 %UTIL AVER-HTM MON-NAME
0 0 0 0 0 0 0 0 0 [36047598]
com/ibm/ws/sib/msgstore/list/ReadWriteLock at A1CA04C8 (Object)
0 0 0 0 0 0 0 0 0 [360475F4]
sun/nio/ch/PollSelectorImpl$InterruptLock at A7C06F58 (Object)   // <=  we get
the lock name after modification
0 0 0 0 0 0 0 0 0 [36047650]
com/ibm/ws/objectpool/ObjectPoolImpl at 9FCAA5F8(Object)
*
//end of example4

   There are several classes found containing these pieces of code:
*src/share/classes/java/lang/SecurityManager.java
src/share/classes/java/lang/reflect/Proxy.java
src/solaris/classes/java/lang/UNIXProcess.java.solaris
src/solaris/classes/sun/nio/ch/PollSelectorImpl.java*

   It will bring some enhancement to performance tools if these modification
can
be applied. Any comments?

-- 
Best Regards,
Sean Chou