RFR: 8139965 - Hang seen when using com.sun.jndi.ldap.search.replyQueueSize
Rob McKenna
rob.mckenna at oracle.com
Fri Oct 26 14:55:19 UTC 2018
Thanks again Daniel,
http://cr.openjdk.java.net/~robm/8139965/webrev.04/
-Rob
On 26/10/18 09:54, Daniel Fuchs wrote:
> Hi Rob,
>
> Now I'm concerned about this method:
>
> 71 synchronized boolean addReplyBer(BerDecoder ber) {
> 72 // check the closed boolean value here as we don't want
> anything
> 73 // to be added to the queue after close() has been called.
> 74 if (cancelled || closed) {
> 75 return false;
> 76 }
> 77
> 78 // Add a new reply to the queue of unprocessed replies.
> 79 try {
> 80 replies.put(ber);
> 81 } catch (InterruptedException e) {
> 82 // ignore
> 83 }
> 84
> 85 // peek at the BER buffer to check if it is a SearchResultDone
> PDU
> 86 try {
> 87 ber.parseSeq(null);
> 88 ber.parseInt();
> 89 completed = (ber.peekByte() == LdapClient.LDAP_REP_RESULT);
> 90 } catch (IOException e) {
> 91 // ignore
> 92 }
> 93 ber.reset();
> 94 return pauseAfterReceipt;
> 95 }
>
> getReplyBer() is not synchronized, so AFAICS there is a
> chance that line 93 executes after another thread as got
> hold of the `ber` object.
>
> Is that an issue? Should the `ber` object be added to
> the reply queue only after it's been reset?
>
> best regards,
>
> -- daniel
>
> On 25/10/2018 21:53, Rob McKenna wrote:
> > Thanks Daniel:
> >
> > http://cr.openjdk.java.net/~robm/8139965/webrev.03/
> >
> > I'm planning to follow up on the test side of things with a separate
> > bug. I think the technique used in some of the recent SQE LDAP tests
> > might be applicable.
> >
> > -Rob
> >
> > On 05/09/18 09:53, Daniel Fuchs wrote:
> > > Hi Rob,
> > >
> > > That looks better but I believe that:
> > >
> > > 1. closed should be volatile since it's read from outside
> > > synchronized block
> > >
> > > 2. it seems there might be a race where the last response
> > > received could be dropped, if the connection is closed
> > > just after it's been pulled from the queue.
> > >
> > > So I would suggest exchanging:
> > >
> > > 115 if (isClosed()) {
> > > 116 return null;
> > > 117 }
> > > 118
> > > 119 return result;
> > >
> > > with:
> > >
> > > return result == EOF ? null : result;
> > >
> > > best regards,
> > >
> > > -- daniel
> > >
> > > On 05/09/2018 02:05, Rob McKenna wrote:
> > > > Thanks for the reviews folks.
> > > >
> > > > I believe the following captures your recommended changes:
> > > >
> > > > http://cr.openjdk.java.net/~robm/8139965/webrev.02/
> > > >
> > > > W.r.t. testing I think this area has been difficult to test
> > > > traditionally. I'll have a dig through the existing testbase (and I'll
> > > > get back to you) to see if there's anything similar but afaik most tests
> > > > simply mimic a bindable dummy ldap server.
> > > >
> > > > Vyom, are you aware of any more rigorous tests / ldap test frameworks?
> > > >
> > > > -Rob
> > > >
> > > > On 04/09/18 10:22, Daniel Fuchs wrote:
> > > > > Hi Rob,
> > > > >
> > > > > I concur with Chris.
> > > > > completed needs to be volatile and close() needs to
> > > > > set a flag and use offer like cancel().
> > > > >
> > > > > The condition for testing for closed then becomes
> > > > > that the flag is set and the queue is empty or has EOF
> > > > > as its head.
> > > > >
> > > > > Is there any way this could be tested by a regression
> > > > > test?
> > > > >
> > > > > best regards,
> > > > >
> > > > > -- daniel
> > > > >
> > > > > On 04/09/2018 10:00, Chris Hegarty wrote:
> > > > > > Rob,
> > > > > >
> > > > > > > On 3 Sep 2018, at 22:48, Rob McKenna <rob.mckenna at oracle.com> wrote:
> > > > > > >
> > > > > > > Hi folks,
> > > > > > >
> > > > > > > I'd like to get a re-review of this change:
> > > > > > >
> > > > > > > https://bugs.openjdk.java.net/browse/JDK-8139965 <https://bugs.openjdk.java.net/browse/JDK-8139965>
> > > > > >
> > > > > > This issue is closed as `will not fix`. I presume you will re-open it before pushing.
> > > > > >
> > > > > > > http://cr.openjdk.java.net/~robm/8139965/webrev/ <http://cr.openjdk.java.net/~robm/8139965/webrev/>
> > > > > >
> > > > > >
> > > > > > 43 private boolean completed;
> > > > > > Won’t `completed` need to be volatile now? ( since the removal of synchronized from hasSearchCompleted )
> > > > > >
> > > > > > LdapRequest.close puts EOF into the queue, but that is a potentially blocking operation ( while holding the lock ). If the queue is at capacity, then it will block forever. This model will only work if `getReplyBer` is always guaranteed to be running concurrently. Is it?
> > > > > >
> > > > > > Please check the indentation of LdapRequest.java L103 ( in
> > > > > > the new file ). It appears, in the webrev, that the trailing `}` is
> > > > > > not lined up.
> > > > > >
> > > > > > The indentation doesn’t look right here either.
> > > > > > 624 if (nparent) {
> > > > > > 625 LdapRequest ldr = pendingRequests;
> > > > > > 626 while (ldr != null) {
> > > > > > 627 ldr.close();
> > > > > > 628 ldr = ldr.next;
> > > > > > 629 }
> > > > > > 630 }
> > > > > > 631 }
> > > > > >
> > > > > > -Chris
> > > > > >
> > > > >
> > >
>
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