On 18-Nov-08, at 12:18 PM, Mark Miller wrote:
Mike Klaas wrote:
autoCommitCount is written in a CommitTracker.synchronized block
only. It is read to print stats in an unsynchronized fashion,
which perhaps could be fixed, though I can't see how it could cause
a problem
lastAddedTime is only written in a call path within a
DirectUpdateHandler2.synchronized block. It is only read in a
CommitTracker.synchronized block. It could read the wrong value,
but I also don't see this causing a problem (a commit might fail to
be scheduled). This could probably also be improved, but doesn't
seem important.
Right. I don't see these as causing a deadlock either, but whatever
happens, its pretty much JVM undefined right, hence 'who
knows' (I'll go with pretty doubtful <g>). I am not so sure its safe
to read a value from an unsynced method whether you care about the
result or not though. Its prob safe for atomic types and volatiles,
but I'm fairly sure your playing with fire doing read/write in and
out of sync. I don't think its just about stale values. But then
again, it probably works 99.9% of the time or something.
Yeah, something like lastAddedTime is worth getting right, even if it
works most of the time. Things like autoCommitCount that read a long
unsynchronized only to display on an admin screen don't concern me as
much.
-Mike
