Re: PG10 - Out of shared memory / invalid memory alloc request size

I don't think this is the issue (Tom's theory sounds more likely). Also
changing the IPC shared memory limit is not going to make any difference
for these later versions of Postgres (>= 9.3) as it uses POSIX shared
memory (I believe the whole point of that change was to avoid the need
to tweak these IPC parameters)!

regards

Mark

On 15/11/17 09:07, Arjun Ranade wrote:
> We will try that.  I am wondering why we need to worry about this in
> pg10 whereas we had no issues with shared memory in 9.4
>
> Thanks,
> Arjun
>
> On Tue, Nov 14, 2017 at 3:05 PM, Alvaro Aguayo Garcia-Rada
> <aaguayo(at)opensysperu(dot)com <mailto:aaguayo(at)opensysperu(dot)com>> wrote:
>
> Try with:
>
> echo "18446744073709551615" > /proc/sys/kernel/shmax
>
> Then restart postgres
>
> Regards,
>
> Alvaro Aguayo
> Operations Manager
> Open Comb Systems E.I.R.L.
>
> Office: (+51-1) 3377813 <tel:%28%2B51-1%29%203377813> | Mobile:
> (+51) 995540103 <tel:%28%2B51%29%20995540103> | (+51) 954183248
> <tel:%28%2B51%29%20954183248>
> Web: www.ocs.pe <http://www.ocs.pe>
>
> ----- Original Message -----
> From: "Arjun Ranade" <ranade(at)nodalexchange(dot)com
> <mailto:ranade(at)nodalexchange(dot)com>>
> To: "Alvaro Aguayo Garcia-Rada" <aaguayo(at)opensysperu(dot)com
> <mailto:aaguayo(at)opensysperu(dot)com>>
> Cc: "pgsql-admin" <pgsql-admin(at)postgresql(dot)org
> <mailto:pgsql-admin(at)postgresql(dot)org>>
> Sent: Tuesday, 14 November, 2017 15:00:03
> Subject: Re: [ADMIN] PG10 - Out of shared memory / invalid memory
> alloc request size
>
> /proc/sys/kernel/shmax = 68719476736
>
>
> On Tue, Nov 14, 2017 at 2:53 PM, Alvaro Aguayo Garcia-Rada <
> aaguayo(at)opensysperu(dot)com <mailto:aaguayo(at)opensysperu(dot)com>> wrote:
>
> > I remember an old issue I had with postgres and shared memory
> being set
> > too low by the distro I was using.
> >
> > What's the value of "/proc/sys/kernel/shmmax"? Try setting to
> > 18446744073709551615
> >
> > Regards,
> >
> > Alvaro Aguayo
> > Operations Manager
> > Open Comb Systems E.I.R.L.
> >
> > Office: (+51-1) 3377813 <tel:%28%2B51-1%29%203377813> | Mobile:
> (+51) 995540103 <tel:%28%2B51%29%20995540103> | (+51) 954183248
> <tel:%28%2B51%29%20954183248>
> > Web: www.ocs.pe <http://www.ocs.pe>
> >
> > ----- Original Message -----
> > From: "Arjun Ranade" <ranade(at)nodalexchange(dot)com
> <mailto:ranade(at)nodalexchange(dot)com>>
> > To: "pgsql-admin" <pgsql-admin(at)postgresql(dot)org
> <mailto:pgsql-admin(at)postgresql(dot)org>>
> > Sent: Tuesday, 14 November, 2017 14:44:08
> > Subject: [ADMIN] PG10 - Out of shared memory / invalid memory alloc
> > request size
> >
> > We recently upgraded a database that a number of developers use from
> > Postgres 9.4 to 10.  Our memory parameters are unchanged.
> >
> > We are seeing a lot of errors that look like this in the
> postgres log:
> >
> > < 2017-11-14 13:13:59 EST [144172] : [1-1]
> > user=[unknown],db=qa16,remote=192.168.104.22(35238) > FATAL:  no
> > PostgreSQL
> > user name specified in startup packet
> > < 2017-11-14 13:52:22 EST [6273] : [1-1]
> > user=deployment_app,db=qa5,remote=192.168.104.83(45384) >
> ERROR:  out of
> > shared memory
> > < 2017-11-14 14:17:53 EST [6200] : [3-1]
> > user=service_tracker_app,db=qa16,remote=192.168.104.22(46996) >
> ERROR:
> > invalid memory alloc request size 34359738368
> >
> > Anecdotally it seems that these errors are happening when
> > powa_take_snapshot() (Postgres workload analyzer) is running as
> well but I
> > can't confirm that.
> >
> > Does anyone know how to debug these types of errors?  And once
> the db is in
> > this state, how do we resolve sessions reporting "Error: invalid
> memory
> > alloc request size" - killing the sessions and having them
> reconnect does
> > not fix the issue.
> >
> > Thanks,
> > Arjun
> >
>
>