Re: [Postgres-xc-developers] A problem in advisory locks (Artifact 3610122)

[Amit K. <ami...@en...>]

On 18 April 2013 02:43, Abbas Butt <abb...@en...> wrote:

> While doing some testing I found that just checking
> res == LOCKACQUIRE_OK
> is not enough, the function should succeed if the lock is already held
> too, hence the condition should be
> (res == LOCKACQUIRE_OK || res == LOCKACQUIRE_ALREADY_HELD)
> Attached patch corrects this problem.


This looks fine to me.

>
>
>
> On Mon, Apr 8, 2013 at 11:23 AM, Abbas Butt <abb...@en...>wrote:
>
>> Thanks. I will commit it later today.
>>
>>
>> On Mon, Apr 8, 2013 at 9:52 AM, Amit Khandekar <
>> ami...@en...> wrote:
>>
>>> Hi Abbas,
>>>
>>> The patch looks good to go.
>>>
>>> -Amit
>>>
>>>
>>> On 6 April 2013 01:02, Abbas Butt <abb...@en...> wrote:
>>>
>>>> Hi,
>>>>
>>>> Consider this test case when run on a single coordinator cluster.
>>>>
>>>> From one session acquire a lock
>>>>
>>>> edb@edb-virtual-machine:/usr/local/pgsql/bin$ ./psql postgres
>>>> psql (PGXC 1.1devel, based on PG 9.2beta2)
>>>> Type "help" for help.
>>>>
>>>> postgres=# select pg_try_advisory_lock(1234,5678);
>>>>  pg_try_advisory_lock
>>>> ----------------------
>>>>  t
>>>> (1 row)
>>>>
>>>>
>>>> and from another terminal try to acquire the same lock
>>>>
>>>> edb@edb-virtual-machine:/usr/local/pgsql/bin$ ./psql postgres
>>>> psql (PGXC 1.1devel, based on PG 9.2beta2)
>>>> Type "help" for help.
>>>>
>>>> postgres=# select pg_try_advisory_lock(1234,5678);
>>>>  pg_try_advisory_lock
>>>> ----------------------
>>>>  t
>>>> (1 row)
>>>>
>>>> Note that the second request succeeds where as the lock is already held
>>>> by the first session.
>>>>
>>>> The problem is that pgxc_advisory_lock neglects the return of
>>>> LockAcquire function in case of single coordinator.
>>>> The attached patch corrects the problem.
>>>>
>>>> Comments are welcome.
>>>>
>>>>
>>>> --
>>>> Abbas
>>>> Architect
>>>> EnterpriseDB Corporation
>>>> The Enterprise PostgreSQL Company
>>>>
>>>> Phone: 92-334-5100153
>>>>
>>>> Website: www.enterprisedb.com
>>>> EnterpriseDB Blog: http://blogs.enterprisedb.com/
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>>>
>>
>>
>> --
>> --
>> Abbas
>> Architect
>> EnterpriseDB Corporation
>> The Enterprise PostgreSQL Company
>>
>> Phone: 92-334-5100153
>>
>> Website: www.enterprisedb.com
>> EnterpriseDB Blog: http://blogs.enterprisedb.com/
>> Follow us on Twitter: http://www.twitter.com/enterprisedb
>>
>> This e-mail message (and any attachment) is intended for the use of
>> the individual or entity to whom it is addressed. This message
>> contains information from EnterpriseDB Corporation that may be
>> privileged, confidential, or exempt from disclosure under applicable
>> law. If you are not the intended recipient or authorized to receive
>> this for the intended recipient, any use, dissemination, distribution,
>> retention, archiving, or copying of this communication is strictly
>> prohibited. If you have received this e-mail in error, please notify
>> the sender immediately by reply e-mail and delete this message.
>>
>
>
>
> --
> --
> Abbas
> Architect
> EnterpriseDB Corporation
> The Enterprise PostgreSQL Company
>
> Phone: 92-334-5100153
>
> Website: www.enterprisedb.com
> EnterpriseDB Blog: http://blogs.enterprisedb.com/
> Follow us on Twitter: http://www.twitter.com/enterprisedb
>
> This e-mail message (and any attachment) is intended for the use of
> the individual or entity to whom it is addressed. This message
> contains information from EnterpriseDB Corporation that may be
> privileged, confidential, or exempt from disclosure under applicable
> law. If you are not the intended recipient or authorized to receive
> this for the intended recipient, any use, dissemination, distribution,
> retention, archiving, or copying of this communication is strictly
> prohibited. If you have received this e-mail in error, please notify
> the sender immediately by reply e-mail and delete this message.
>