Date: Mon, 22 Aug 2022 15:45:11 +0800
From: Zhang Mingli <zmlpostgres@gmail.com>
To: ma100@hotmail.com, pgsql-bugs@lists.postgresql.org
Message-ID: <46726dc2-ca8c-426e-bb4e-cfa47ce48d9e@Spark>
In-Reply-To: <17591-6ae23a6598b64c4e@postgresql.org>
References: <17591-6ae23a6598b64c4e@postgresql.org>
Subject: Re: BUG #17591: elog(ERROR) cause SharedSnapshotLock deadlock
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Hi,

Didn=E2=80=99t see any bugs here, it report an error and the transaction =
will end and release all resources.

Regards,
Zhang Mingli
On Aug 22, 2022, 14:58 +0800, PG Bug reporting form <noreply=40postgresql=
.org>, wrote:
> The following bug has been logged on the website:
>
> Bug reference: 17591
> Logged by: ma liangzhu
> Email address: ma100=40hotmail.com
> PostgreSQL version: 14.5
> Operating system: centos7
> Description:
>
> in lock.c, we can see code Release lock before return , e.g.
>
> =60=60=60c
> 996: LockAcquireExtended
> =7B
> LWLockAcquire(partitionLock, LW=5FEXCLUSIVE);
>
> proclock =3D SetupLockInTable( );
> if (=21proclock)
> =7B
> LWLockRelease(partitionLock); --- Release lock before return
> ereport(ERROR,)
> =7D
> =7D
> =60=60=60
>
> bug we can see some code doesn't release the lock. Does it may cause
> deadlock=3F
>
> =60=60=60c
> LockRelease()
> =7B
> LWLockAcquire(partitionLock, LW=5FEXCLUSIVE);
>
> lock =3D locallock->lock;
> if (=21lock)
> =7B
> lock =3D (LOCK *) hash=5Fsearch=5Fwith=5Fhash=5Fvalue( );
> if (=21lock)
> 2126: elog(ERROR, =22failed to re-find shared lock object=22); -- exit
> without release
> =7D
> =60=60=60
>

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<div name=3D=22messageBodySection=22>
<div dir=3D=22auto=22>Hi,<br />
<br />
Didn=E2=80=99t see any bugs here, it report an error and the transaction =
will end and release all resources.<br /></div>
</div>
<div name=3D=22messageSignatureSection=22><br />
<div class=3D=22match=46ont=22>Regards,
<div dir=3D=22auto=22>Zhang Mingli</div>
</div>
</div>
<div name=3D=22messageReplySection=22>On Aug 22, 2022, 14:58 +0800, PG Bu=
g reporting form &lt;noreply=40postgresql.org&gt;, wrote:<br />
<blockquote type=3D=22cite=22 style=3D=22border-left-color: grey; border-=
left-width: thin; border-left-style: solid; margin: 5px 5px;padding-left:=
 10px;=22>The following bug has been logged on the website:<br />
<br />
Bug reference: 17591<br />
Logged by: ma liangzhu<br />
Email address: ma100=40hotmail.com<br />
PostgreSQL version: 14.5<br />
Operating system: centos7<br />
Description:<br />
<br />
in lock.c, we can see code Release lock before return , e.g.<br />
<br />
=60=60=60c<br />
996: LockAcquireExtended<br />
=7B<br />
LWLockAcquire(partitionLock, LW=5FEXCLUSIVE);<br />
<br />
proclock =3D SetupLockInTable( );<br />
if (=21proclock)<br />
=7B<br />
LWLockRelease(partitionLock); --- Release lock before return<br />
ereport(ERROR,)<br />
=7D<br />
=7D<br />
=60=60=60<br />
<br />
bug we can see some code doesn't release the lock. Does it may cause<br /=
>
deadlock=3F<br />
<br />
=60=60=60c<br />
LockRelease()<br />
=7B<br />
LWLockAcquire(partitionLock, LW=5FEXCLUSIVE);<br />
<br />
lock =3D locallock-&gt;lock;<br />
if (=21lock)<br />
=7B<br />
lock =3D (LOCK *) hash=5Fsearch=5Fwith=5Fhash=5Fvalue( );<br />
if (=21lock)<br />
2126: elog(ERROR, =22failed to re-find shared lock object=22); -- exit<br=
 />
without release<br />
=7D<br />
=60=60=60<br />
<br /></blockquote>
</div>
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