Re: question on mon memory usage

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On Mon, 25 Feb 2013, Travis Rhoden wrote:
> Right now everything is on a stock setup.   I believe that means no core file.
> 
> root@ceph2:~# ulimit -c
> 0
> 
> Doh.  I don't see anything in the ceph init script that would increase
> this for the ceph-* processes.  Which is probably a good thing, of
> course.

Can you try something like this to grab an image of the process memory?

#!/bin/bash
grep rw-p /proc/$1/maps | sed -n 's/^\([0-9a-f]*\)-\([0-9a-f]*\) .*$/\1 \2/p' | while read start stop; do gdb --batch --pid $1 -ex "dump memory $1-$start-$stop.dump 0x$start 0x$stop"; done

(from http://stackoverflow.com/questions/12977179/reading-living-process-memory-without-interrupting-it-proc-kcore-is-an-option)

THanks!
sage





> 
> On Mon, Feb 25, 2013 at 7:40 PM, Sage Weil <sage@xxxxxxxxxxx> wrote:
> > On Mon, 25 Feb 2013, Travis Rhoden wrote:
> >> Joao,
> >>
> >> Happy to help if I can.  responses inline.
> >>
> >> On Mon, Feb 25, 2013 at 4:05 PM, Joao Eduardo Luis
> >> <joao.luis@xxxxxxxxxxx> wrote:
> >> > On 02/25/2013 07:59 PM, Travis Rhoden wrote:
> >> >>
> >> >> Hi folks,
> >> >>
> >> >> A question about memory usage by the Mon.  I have a cluster that is
> >> >> being used exclusively for RBD (no CephFS/mds).  I have 5 mons, and
> >> >> one is slowly but surely using a heck of a lot more memory than the
> >> >> others:
> >> >>
> >> >> # for x in ceph{1..5}; do ssh $x 'ps aux | grep ceph-mon | grep -v grep';
> >> >> done
> >> >> root     31034  5.2  0.1 312116 75516 ?        Ssl  Feb14 881:51
> >> >> /usr/bin/ceph-mon -i a --pid-file /var/run/ceph/mon.a.pid -c
> >> >> /etc/ceph/ceph.conf
> >> >> root     29361  4.8 53.9 22526128 22238080 ?   Ssl  Feb14 822:36
> >> >> /usr/bin/ceph-mon -i b --pid-file /var/run/ceph/mon.b.pid -c
> >> >> /tmp/ceph.conf.31144
> >> >> root     28421  7.0  0.1 273608 88608 ?        Ssl  Feb20 516:48
> >> >> /usr/bin/ceph-mon -i c --pid-file /var/run/ceph/mon.c.pid -c
> >> >> /tmp/ceph.conf.10625
> >> >> root     25876  4.8  0.1 240752 84048 ?        Ssl  Feb14 816:54
> >> >> /usr/bin/ceph-mon -i d --pid-file /var/run/ceph/mon.d.pid -c
> >> >> /tmp/ceph.conf.31537
> >> >> root     24505  4.8  0.1 228720 79284 ?        Ssl  Feb14 818:14
> >> >> /usr/bin/ceph-mon -i e --pid-file /var/run/ceph/mon.e.pid -c
> >> >> /tmp/ceph.conf.31734
> >> >>
> >> >> As you can see, one is up over 20GB, while the others are < 100MB.
> >> >>
> >> >> Is this normal?  The box has plenty of RAM -- I'm wondering if this is
> >> >> a memory leak, or if it's just slowly finding more things it can cache
> >> >> and such.
> >> >>
> >> >
> >> > Hi Travis,
> >> >
> >> > Which version are you running?
> >> >
> >> # ceph --version
> >> ceph version 0.56.3 (6eb7e15a4783b122e9b0c85ea9ba064145958aa5)
> >>
> >> That's the case all around OSDs, mons, librbd clients, everything in my cluster
> >> > This has been something that pops in the list every now and then, and I've
> >> > spent a considerable amount of time trying to track it down.
> >> >
> >> > My current suspicion lies on the in-memory pgmap growing, and growing, and
> >> > growing... and it usually hits the leader the worst.  Can you please confirm
> >> > that mon.b is indeed the leader?
> >> I'm not 100% sure how to do that.  I'm guessing rank 0 from the
> >> following output?
> >>
> >> # ceph quorum_status
> >> { "election_epoch": 32,
> >>   "quorum": [
> >>         0,
> >>         1,
> >>         2,
> >>         3,
> >>         4],
> >>   "monmap": { "epoch": 1,
> >>       "fsid": "d5229b51-5321-48d2-bbb2-16062abb1992",
> >>       "modified": "2013-01-21 17:58:14.389411",
> >>       "created": "2013-01-21 17:58:14.389411",
> >>       "mons": [
> >>             { "rank": 0,
> >>               "name": "a",
> >>               "addr": "10.10.30.1:6789\/0"},
> >>             { "rank": 1,
> >>               "name": "b",
> >>               "addr": "10.10.30.2:6789\/0"},
> >>             { "rank": 2,
> >>               "name": "c",
> >>               "addr": "10.10.30.3:6789\/0"},
> >>             { "rank": 3,
> >>               "name": "d",
> >>               "addr": "10.10.30.4:6789\/0"},
> >>             { "rank": 4,
> >>               "name": "e",
> >>               "addr": "10.10.30.5:6789\/0"}]}}
> >>
> >> That would seem to imply that mon a is the leader.  mon b is
> >> definitely the problem child at the moment.
> >>
> >> I did a quick check, and mon b has grown by ~ 400MB since my previous
> >> email.  So we're looking at a little under 100MB/hr, perhaps.  Not
> >> sure if that's consistent or not.  WIll certainly check again in the
> >> morning.
> >
> > Do you know if there is a core file ulimit set on that process?  If the
> > core is configured to go somewhere, a kill -SEGV on it would generate a
> > core that would help us figure out what the memory is consumed by.
> >
> > Thanks!
> > sage
> >
> 
> 
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