Subject: Re: Lock contention high
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Ashkil Dighin <ashkildighin76@gmail.com>,
 pgsql-performance@lists.postgresql.org
References: 
 <CAH6zzqCNtbCDSSFweuZp93R7TOxfEB8f75iosExb6sutyAa-Uw@mail.gmail.com>
 <20211013164805.GC27491@telsasoft.com>
From: MichaelDBA <MichaelDBA@sqlexec.com>
Message-ID: <0b264a08-b723-eec2-c667-49f17b0a487c@sqlexec.com>
Date: Wed, 13 Oct 2021 14:15:34 -0400
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> 1.Is there a way to tune the lock contention ?
> 2.Is any recommendations to tune/reduce the lock contention via postgres.conf
I think you'd want to find *which* LW locks are being waited on, to see if it's
something that can be easily tuned.

You can check pg_stat_activity, or maybe create a cronjob to record its content
for later analysis.


Hello,

Also turn on log_lock_waits so you can evaluate the actual SQL causing 
the problems in the PG log files.  Thinking ahead, you may want to 
consider if using advisory locks from the application side of things 
might be helpful to manage locks in a more pessimistic way.  Also, join 
with pg_locks table to find out the specific resources that are in 
contention.

Regards,
Michael Vitale


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<blockquote type="cite"><pre wrap="">1.Is there a way to tune the lock contention ?
2.Is any recommendations to tune/reduce the lock contention via postgres.conf
</pre></blockquote>


<pre wrap="">I think you'd want to find *which* LW locks are being waited on, to see if it's
something that can be easily tuned.

You can check pg_stat_activity, or maybe create a cronjob to record its content
for later analysis.


Hello,
</pre>

Also turn on <span style="font-weight: bold;">log_lock_waits</span> so 
you can evaluate the actual SQL causing the problems in the PG log 
files.  Thinking ahead, you may want to consider if using advisory locks
 from the application side of things might be helpful to manage locks in
 a more pessimistic way.  Also, join with <span style="font-weight: 
bold;">pg_locks</span> table to find out the specific resources that are
 in contention.<br>
<br>
Regards,<br>
Michael Vitale<br>
<br>
<br>
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