Ok. I’ll see about tracking down the logs (set to stderr for these tasks), and
the metadata stuff looks interesting for future association.
Thanks,
Chris
On 9/14/16, 5:04 PM, "Gregory Farnum" <gfar...@redhat.com> wrote:
On Wed, Sep 14, 2016 at 7:02 AM, Heller, Chris <chel...@akamai.com> wrote:
> I am making use of CephFS plus the cephfs-hadoop shim to replace HDFS in a
> system I’ve been experimenting with.
>
>
>
> I’ve noticed that a large number of my HDFS clients have a ‘num_caps’
value
> of 16385, as seen when running ‘session ls’ on the active mds. This
appears
> to be one larger than the default value for ‘client_cache_size’ so I
presume
> some relation, though I have not seen any documentation to corroborate
this.
>
>
>
> What I was hoping to do is track down which ceph client is actually
holding
> all these ‘caps’, but since my system can have work scheduled dynamically
> and multiple clients can be running on the same host, its not obvious how
to
> associate the client ‘id’ as reported by ‘session ls’ with any one process
> on the give host.
>
>
>
> Is there steps I can follow to back track the client ‘id’ to a process id?
Hmm, it looks like we no longer directly associate the process ID with
the client session. There is a "client metadata" config option you can
fill in with arbitrary "key=value[,key2=value2]* strings if you can
persuade Hadoop to set that to something useful on each individual
process. If you have logging or admin sockets enabled then you should
also be able to find them named by client ID and trace those back to
the pid with standard linux tooling.
I've created a ticket to put this back in as part of the standard
metadata: http://tracker.ceph.com/issues/17276
-Greg
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