RFR: 8139965 - Hang seen when using com.sun.jndi.ldap.search.replyQueueSize
Daniel Fuchs
daniel.fuchs at oracle.com
Fri Oct 26 08:54:32 UTC 2018
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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