[Gluster-devel] Logging in a multi-brick daemon

Atin Mukherjee amukherj at redhat.com
Thu Feb 16 01:51:31 UTC 2017

On Thu, 16 Feb 2017 at 04:09, Jeff Darcy <jdarcy at redhat.com> wrote:

> One of the issues that has come up with multiplexing is that all of the
> bricks in a process end up sharing a single log file.  The reaction from
> both of the people who have mentioned this is that we should find a way to
> give each brick its own log even when they're in the same process, and make
> sure gf_log etc. are able to direct messages to the correct one.  I can
> think of ways to do this, but it doesn't seem optimal to me.  It will
> certainly use up a lot of file descriptors.  I think it will use more
> memory.  And then there's the issue of whether this would really be better
> for debugging.  Often it's necessary to look at multiple brick logs while
> trying to diagnose this problem, so it's actually kind of handy to have
> them all in one file.  Which would you rather do?
> (a) Weave together entries in multiple logs, either via a script or in
> your head?
> (b) Split or filter entries in a single log, according to which brick
> they're from?
> To me, (b) seems like a much more tractable problem.  I'd say that what we
> need is not multiple logs, but *marking of entries* so that everything
> pertaining to one brick can easily be found.  One way to do this would be
> to modify volgen so that a brick ID (not name because that's a path and
> hence too long) is appended/prepended to the name of every translator in
> the brick.  Grep for that brick ID, and voila!  You now have all log
> messages for that brick and no other.  A variant of this would be to leave
> the names alone and modify gf_log so that it adds the brick ID
> automagically (based on a thread-local variable similar to THIS).  Same
> effect, other than making translator names longer, so I'd kind of prefer
> this approach.  Before I start writing the code, does anybody else have any
> opinions, preferences, or alternatives I haven't mentioned yet?

I like this idea. +1

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- Atin (atinm)
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