Andreas L Delmelle wrote:
Hi Andreas,
A splendid idea!
I already thought my approach to be lacking somewhere, although it was
too late last night to see where exactly. First off, the flag should,
of course be declared 'volatile'. If not, then there is no guarantee a
thread will see the most recent state. More importantly, there is the
matter of cleanups that were already running at the time rehash()
started acquiring its locks, as you point out.
Introducing another dummy Object to synchronize on, seems like a very
clean solution. The flag could still be used to avoid unnecessary
cleanups or rehashes from being started. Synchronizing on a mutual
object would still launch them, but they would merely have to wait.
I'm not sure another object to synchronize on is required as the 2
threads both already synchronize on the segments. I'm not familar with
the PropertyCache and I was expecting you to say that the rehash method
couldn't start whilst existing cleanups were running because of the sync
on segments. But I guess if that was working then we wouldn't need the
boolean flag either :-/
It's not clear to me from a quick glance at the code exactly what
segments within the Property Cache are, but gut feel is that
synchronization between the 2 threads needs more work. For now I will
just leave the null check in place since I don't have time to persue
this issue.
Regarding your observation of the OutOfMemoryError: this might need
investigating. Do you have any indication as to which types of objects
are leaking?
Yes I have been running a profiling tool on FOP this morning and
discovered that the PropertyCache$CacheEntry inner class is the one that
seems to grow and grow (its +89,000 instances after 1100 documents), but
you knew that already ;)
Chris
