Обсуждение: [ADMIN] High CPU usage from a vacuum process but does nothing

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[ADMIN] High CPU usage from a vacuum process but does nothing

От
"Boris S."
Дата:
After migrating the server to a bigger machine, I'm noticing an odd 
behaviour. If I begin vacuuming manually, it starts OK:

<snip>
0 pages are entirely empty.
CPU 0.00s/0.00u sec elapsed 0.00 sec.
INFO:  analyzing "public.table024484"
INFO:  "table024484": scanned 111123 of 111123 pages, containing 4909226 
live rows and 0 dead rows; 150000 rows in sample, 4909226 estimated 
total rows

But then it gets stuck indefinitely with high CPU usage and command 
never exits. kill -TERM isn't helping, process stays on with ~99% CPU 
usage. Stracing this process gets me just:

strace: Process 102011 attached
strace: [ Process PID=102011 runs in x32 mode. ]

Which is an odd message, all other processes give normal strace output.

latest pgsql 9.5 (same on old and new machine)
Ubuntu 16.04

Values in "cat /proc/102011/io" stay the same.

Autovacuum and other processes, queries aren't affected and can be 
straced normally. Disk IO is low (checked with iostat)

Any ideas on what else to try?


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Re: [ADMIN] High CPU usage from a vacuum process but does nothing

От
"Boris S."
Дата:
To sum it up, after reboot it looks alright, vacuum finishes promptly.


On 04/10/2017 19:28, Boris S. wrote:
> After migrating the server to a bigger machine, I'm noticing an odd 
> behaviour. If I begin vacuuming manually, it starts OK:
>
> <snip>
> 0 pages are entirely empty.
> CPU 0.00s/0.00u sec elapsed 0.00 sec.
> INFO:  analyzing "public.table024484"
> INFO:  "table024484": scanned 111123 of 111123 pages, containing 
> 4909226 live rows and 0 dead rows; 150000 rows in sample, 4909226 
> estimated total rows
>
> But then it gets stuck indefinitely with high CPU usage and command 
> never exits. kill -TERM isn't helping, process stays on with ~99% CPU 
> usage. Stracing this process gets me just:
>
> strace: Process 102011 attached
> strace: [ Process PID=102011 runs in x32 mode. ]
>
> Which is an odd message, all other processes give normal strace output.
>
> latest pgsql 9.5 (same on old and new machine)
> Ubuntu 16.04
>
> Values in "cat /proc/102011/io" stay the same.
>
> Autovacuum and other processes, queries aren't affected and can be 
> straced normally. Disk IO is low (checked with iostat)
>
> Any ideas on what else to try?
>
>



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