On 10.4.14 2:24 , Alexander Klimetschek wrote:
On 09.04.2014, at 07:15, Michael Dürig <[email protected]> wrote:
On 9.4.14 4:12 , Rob Ryan wrote:
It would be appropriate to change the warning to warn about
concurrent reads as well. That would help highlight performance
risks.
There is such a warning actually. The discussion here was about the
incorrect warning that is issued when writing concurrently.
So when 2 threads use the same session for read operations, then you
get another warning ("concurrent access")?
Right but only at debug level.
If the threads are synchronized, so one finishes its session
operations, then the other thread uses it (not in parallel), and when
that other thread has finished, the first one again reads from the
session, would you get a warning then? AFAIC, the messages are
triggered only when it has to wait for another thread.
Exactly. Each operation tries to acquire a lock and logs a warning if it
fails before eventually blocking on that lock:
if (!lock.tryLock()) {
// log concurrent access
lock.lock();
}
try {
// repository operation
} finally {
lock.unlock();
}
See
https://github.com/apache/jackrabbit-oak/blob/trunk/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/delegate/SessionDelegate.java#L264
Michael
I know, concurrent use of sessions must be avoided. I am just curious
to fully understand the issue I am seeing.
Cheers, Alex
