Thread: How Many PG_Locks are considered too many

How Many PG_Locks are considered too many

From
Renato Oliveira
Date:

Hi

 

I have few questions, if anyone could help me, it will be very much appreciated.

 

We have a Nagios plugin, which monitors pg_locks and almost daily we see 3000 to 40000 pg_locks.

 

Can we just ignore them, can we let them grow without worrying?

How many pg_locks are considered unsafe for any given postgres server?

 

Thank you

 

Renato

 

 

Re: [ADMIN] How Many PG_Locks are considered too many

From
Peter Eisentraut
Date:
On 7/30/15 6:13 AM, Renato Oliveira wrote:
> We have a Nagios plugin, which monitors pg_locks and almost daily we see
> 3000 to 40000 pg_locks.
>
> Can we just ignore them, can we let them grow without worrying?
>
> How many pg_locks are considered unsafe for any given postgres server?

That depends on how many concurrent clients you have and what they are
doing.  Every table access will at least create a share lock of some
kind, so if you have a lot of activity that does a lot of things, you
will see a lot of locks, but that doesn't impact database performance in
a significant way.

I don't think monitoring the absolute number of locks is useful.  You
might want to chart it, to compare over time.  If you want to monitor
locks, you could monitor lock waits, which you can get by checking the
server log.



Re: [ADMIN] How Many PG_Locks are considered too many

From
Renato Oliveira
Date:
Peter thank you much appreciated

Sent from my iPhone

> On 30 Jul 2015, at 14:54, Peter Eisentraut <peter_e@gmx.net> wrote:
>
>> On 7/30/15 6:13 AM, Renato Oliveira wrote:
>> We have a Nagios plugin, which monitors pg_locks and almost daily we see
>> 3000 to 40000 pg_locks.
>>
>> Can we just ignore them, can we let them grow without worrying?
>>
>> How many pg_locks are considered unsafe for any given postgres server?
>
> That depends on how many concurrent clients you have and what they are
> doing.  Every table access will at least create a share lock of some
> kind, so if you have a lot of activity that does a lot of things, you
> will see a lot of locks, but that doesn't impact database performance in
> a significant way.
>
> I don't think monitoring the absolute number of locks is useful.  You
> might want to chart it, to compare over time.  If you want to monitor
> locks, you could monitor lock waits, which you can get by checking the
> server log.
>



Re: [ADMIN] How Many PG_Locks are considered too many

From
John Scalia
Date:
Seconding Peter on this one; it's a lot more important should one of those locks be hanging around, say for hours or days, not how many have come and gone.
--
Jay

On Thu, Jul 30, 2015 at 8:57 AM, Renato Oliveira <Renato.Oliveira@cantabcapital.com> wrote:
Peter thank you much appreciated

Sent from my iPhone

> On 30 Jul 2015, at 14:54, Peter Eisentraut <peter_e@gmx.net> wrote:
>
>> On 7/30/15 6:13 AM, Renato Oliveira wrote:
>> We have a Nagios plugin, which monitors pg_locks and almost daily we see
>> 3000 to 40000 pg_locks.
>>
>> Can we just ignore them, can we let them grow without worrying?
>>
>> How many pg_locks are considered unsafe for any given postgres server?
>
> That depends on how many concurrent clients you have and what they are
> doing.  Every table access will at least create a share lock of some
> kind, so if you have a lot of activity that does a lot of things, you
> will see a lot of locks, but that doesn't impact database performance in
> a significant way.
>
> I don't think monitoring the absolute number of locks is useful.  You
> might want to chart it, to compare over time.  If you want to monitor
> locks, you could monitor lock waits, which you can get by checking the
> server log.
>



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Re: [ADMIN] How Many PG_Locks are considered too many

From
Merlin Moncure
Date:
On Thu, Jul 30, 2015 at 9:19 AM, John Scalia <jayknowsunix@gmail.com> wrote:
> Seconding Peter on this one; it's a lot more important should one of those
> locks be hanging around, say for hours or days, not how many have come and
> gone.

Also, it's good to focus on *ungranted* locks.   Typically the only
time I care about granted locks is to find out which process is
keeping my other process getting its lock granted.

merlin


Re: [ADMIN] How Many PG_Locks are considered too many

From
Renato Oliveira
Date:
Thank you appreciated

Sent from my iPhone

> On 30 Jul 2015, at 20:05, Merlin Moncure <mmoncure@gmail.com> wrote:
>
>> On Thu, Jul 30, 2015 at 9:19 AM, John Scalia <jayknowsunix@gmail.com> wrote:
>> Seconding Peter on this one; it's a lot more important should one of those
>> locks be hanging around, say for hours or days, not how many have come and
>> gone.
>
> Also, it's good to focus on *ungranted* locks.   Typically the only
> time I care about granted locks is to find out which process is
> keeping my other process getting its lock granted.
>
> merlin
>