On Wed, Mar 7, 2018 at 3:50 PM, Alvaro Herrera
wrote:
>
> Scott Frazer wrote:
>
> > It's only happening on the read replicas, though. I've just set my
master
> > to handle all the traffic, but that's not really sustainable
>
> I failed to notice at start of thread that these were replicas. I
> su
Scott Frazer wrote:
> Currently this seems to be happening when the server just starts taking
> connections. It doesn't even need time to scale up anymore (previously it
> took about 8 hours for the problem to re-appear)
>
> It's only happening on the read replicas, though. I've just set my maste
On Wed, Mar 7, 2018 at 10:39 AM, Alvaro Herrera
wrote:
>
> Laurenz Albe wrote:
> I think you could get in this situation if the range of open
> transactions exceeds what fits in the buffers for subtrans.c pages, and
> the subtransaction cache overflows (64 entries apiece;
> PGPROC_MAX_CACHED_SUBXI
Laurenz Albe wrote:
> Scott Frazer wrote:
> > Hi, we have a Postgres 9.6 setup using replication that has recently
> > started seeing a lot of processes stuck in
> > "SubtransControlLock" as a wait_event on the read-replicas. Like this, only
> > usually about 300-800 of them:
> >
> >
> > 17970
Scott Frazer wrote:
>
> On Wed, Mar 7, 2018 at 9:52 AM, Laurenz Albe wrote:
> > Scott Frazer wrote:
> > > Hi, we have a Postgres 9.6 setup using replication that has recently
> > > started seeing a lot of processes stuck in
> > > "SubtransControlLock" as a wait_event on the read-replicas. Like t
Server version is 9.6.5
Is there a decent guide to getting a stack trace on Centos7 when using the
official Postgres repo? trying to follow the Fedora guide put the debug
info for 9.2.23 on the box instead of the 9.6.5 version.
On Wed, Mar 7, 2018 at 9:52 AM, Laurenz Albe
wrote:
> Scott Frazer
Scott Frazer wrote:
> Hi, we have a Postgres 9.6 setup using replication that has recently started
> seeing a lot of processes stuck in
> "SubtransControlLock" as a wait_event on the read-replicas. Like this, only
> usually about 300-800 of them:
>
>
> 179706 | LWLockNamed | SubtransContro
These don't seem like normal locks. Nothing shows up in a "SELECT
relation::regclass, * FROM pg_locks WHERE NOT GRANTED;"
These processes are all active but the wait_event and wait_event_type
fields indicate they are waiting on (I believe) shared memory locks.
pid | usesysid | usename|
For such issues, I find this view very useful (the first one):
https://wiki.postgresql.org/wiki/Lock_Monitoring
Examine blocking_pid's , and tell us what kind of operation is blocking
the other processes . Also, are there many long running transactions in
your server?
2018-03-06 21:24 GMT-06:00
Hi, we have a Postgres 9.6 setup using replication that has recently
started seeing a lot of processes stuck in "SubtransControlLock" as a
wait_event on the read-replicas. Like this, only usually about 300-800 of
them:
179706 | LWLockNamed | SubtransControlLock
186602 | LWLockNamed | S
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