[Hypercontent-users] Important patch for all HyperContent 2.x deployers

[Alex V. <al...@bi...>]

Hi everybody,
	Recently I've been running HyperContent more in JDK 1.5, and I've  
noticed very occasional hangs, which of course are very difficult to  
reproduce.  I was fortunate to reproduce it while I had the debugger  
on the other day, so I was able to quickly identify the cause.  I'm  
not certain whether this bug actually affects 1.4 JVMs or not, but  
the fix should be safe for any JVM level.

The cause was that a literal String was being used for  
synchronization in a heavily used class; the JDK was interning that  
string so that multiple instances of the class were sharing the same  
lock, when they should each have had there own, and in certain  
circumstances this would lead to a deadlock.  This should also have  
had a negative impact on scalability, since it would prevent multiple  
transactional IO operations from happening concurrently.  This bug  
has been present since April 6, 2005!

The class in question is  
org.hypercontent.data.impl.AbstractDataStore, and the fix involved  
changing

  protected final Object storeLock="AbstractDataStore.storeLock";

to

  protected final Object storeLock=new Object();


The fix has been checked into CVS.


-Alex