another note on this, i stopped my client and after about 35 minutes the
compaction did complete, no more pending in compaction-pool. however
the Index, Data, and Filter files still exist with lots of data in them.
"Compact" files exist for all but 4 of the Data files - these "compact"
files are zero length.
thx!
On Thu, 2009-12-03 at 15:40 -0800, B. Todd Burruss wrote:
> in my situation it seems like the compaction process is being starved.
> i'm hitting the server hard for the last 45 minutes and the compaction
> pool is sitting at 1 active, 25 pending, and 7 completed. it has been
> at 1 active and 7 completed for about 20 minutes. the pending have been
> growing steadily since then. and as i was typing it finally finished
> another compaction, so they must be just taking forever.
>
> snapshots of nodeprobe and iostats follow:
>
> Pool Name Active Pending Completed
> FILEUTILS-DELETE-POOL 0 0 116
> MESSAGING-SERVICE-POOL 0 0 0
> STREAM-STAGE 0 0 0
> RESPONSE-STAGE 0 0 0
> ROW-READ-STAGE 1 4 8652560
> LB-OPERATIONS 0 0 0
> COMMITLOG 1 0 14695623
> MESSAGE-DESERIALIZER-POOL 0 0 0
> GMFD 0 0 0
> LB-TARGET 0 0 0
> CONSISTENCY-MANAGER 0 0 0
> ROW-MUTATION-STAGE 1 1 14692604
> MESSAGE-STREAMING-POOL 0 0 0
> LOAD-BALANCER-STAGE 0 0 0
> FLUSH-SORTER-POOL 0 0 28
> MEMTABLE-POST-FLUSHER 0 0 28
> COMPACTION-POOL 1 25 7
> FLUSH-WRITER-POOL 0 0 28
> HINTED-HANDOFF-POOL 0 0 0
>
>
> avg-cpu: %user %nice %system %iowait %steal %idle
> 61.85 0.00 26.68 7.73 0.00 3.74
>
> Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
> sda 246.00 11456.00 18528.00 11456 18528
> sda2 23074.00 20.50 1854.00 20 1854
> sda1 0.00 0.00 0.00 0 0
>
>
>
>
> On Thu, 2009-12-03 at 17:05 -0600, Jonathan Ellis wrote:
> > Thanks for looking into this. Doesn't seem like there's much
> > low-hanging fruit to make compaction faster but I'll keep that in the
> > back of my mind.
> >
> > -Jonathan
> >
> > On Thu, Dec 3, 2009 at 4:58 PM, Freeman, Tim <tim.freeman@hp.com> wrote:
> > >>So this is working as designed, but the design is poor because it
> > >>causes confusion. If you can open a ticket for this that would be
> > >>great.
> > >
> > > Done, see:
> > >
> > > https://issues.apache.org/jira/browse/CASSANDRA-599
> > >
> > >>What does iostat -x 10 (for instance) say about the disk activity?
> > >
> > > rkB/s is consistently high, and wkB/s varies. This is a typical entry with
wkB/s at the high end of its range:
> > >
> > >>avg-cpu: %user %nice %sys %iowait %idle
> > >> 1.52 0.00 1.70 27.49 69.28
> > >>
> > >>Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s avgrq-sz
avgqu-sz await svctm %util
> > >>sda 3.10 3249.25 124.08 29.67 26299.30 26288.11 13149.65 13144.06
342.04 17.75 92.25 5.98 91.92
> > >>sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
> > >>sda2 3.10 3249.25 124.08 29.67 26299.30 26288.11 13149.65 13144.06
342.04 17.75 92.25 5.98 91.92
> > >>sda3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
> > >
> > > and at the low end:
> > >
> > >>avg-cpu: %user %nice %sys %iowait %idle
> > >> 1.50 0.00 1.77 25.80 70.93
> > >>
> > >>Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s avgrq-sz
avgqu-sz await svctm %util
> > >>sda 3.40 817.10 128.60 17.70 27828.80 6600.00 13914.40 3300.00
235.33 6.13 56.63 6.21 90.81
> > >>sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
> > >>sda2 3.40 817.10 128.60 17.70 27828.80 6600.00 13914.40 3300.00
235.33 6.13 56.63 6.21 90.81
> > >>sda3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
> > >
> > > Tim Freeman
> > > Email: tim.freeman@hp.com
> > > Desk in Palo Alto: (650) 857-2581
> > > Home: (408) 774-1298
> > > Cell: (408) 348-7536 (No reception business hours Monday, Tuesday, and Thursday;
call my desk instead.)
> > >
> > >
> > > -----Original Message-----
> > > From: Jonathan Ellis [mailto:jbellis@gmail.com]
> > > Sent: Thursday, December 03, 2009 2:45 PM
> > > To: cassandra-user@incubator.apache.org
> > > Subject: Re: Persistently increasing read latency
> > >
> > > On Thu, Dec 3, 2009 at 4:34 PM, Freeman, Tim <tim.freeman@hp.com> wrote:
> > >>>Can you tell if the system is i/o or cpu bound during compaction?
> > >>
> > >> It's I/O bound. It's using ~9% of 1 of 4 cores as I watch it, and all
it's doing right now is compactions.
> > >
> > > What does iostat -x 10 (for instance) say about the disk activity?
> > >
>
>
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