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From: Rocky Dunlap via lttng-dev <lttng-dev@lists.lttng.org>
To: Jonathan Rajotte-Julien <jonathan.rajotte-julien@efficios.com>
Cc: lttng-dev@lists.lttng.org
Subject: Re: Large number of stream files in CTF trace -- too many file handles
Date: Mon, 16 Mar 2020 21:38:11 -0600	[thread overview]
Message-ID: <CADtyBo7J-E0C_Ap-7tztdd-PpHZwDUXBVqkT_mp_O3x9h=Qy5g@mail.gmail.com> (raw)
In-Reply-To: <20200316145125.GC14185@joraj-alpa>


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Jonathan,

Increasing the soft FD limit worked great, both for the command line and
the Python script.  Thanks for the help!

Rocky

On Mon, Mar 16, 2020 at 8:51 AM Jonathan Rajotte-Julien <
jonathan.rajotte-julien@efficios.com> wrote:

> Hi,
>
> > If this is not the right approach, how should I proceed?  E.g., should
> the
> > source-ctf-fs manage a limited pool of file handles?  I would think this
> > would be pretty inefficient as you would need to constantly open/close
> > files--expensive.
>
> I would probably start looking at the soft and hardlimit for the
> babeltrace2
> process in terms of open file:
>
> On my machine:
>
> joraj@~[]$ ulimit -Sn
> 1024
>
> joraj@~[]$ ulimit -Hn
> 1048576
>
> That is a lot of headspace.
>
> I might have a setting somewhere increasing the base hardlimit but
> in any case you will see how much room you have.
>
> Based on the number of streams you have, I would say that you will
> need more than 2000 as a base soft limit for this trace.
>
> We do have a FD pooling system in place in another project we maintain
> (lttng-tools[1] GPL-2.0) that might be pertinent for babeltrace2 at some
> point
> in time. As for the overhead that would occur in a scenario with not
> enough FD
> available, I think it is a good compromise between either reading a trace
> or
> not reading it at all. A warning informing the user that we reached
> the limit of the pool might be a good start in such case.
>
> [1] https://github.com/lttng/lttng-tools/tree/master/src/common/fd-tracker
>
> Cheers
>
> --
> Jonathan Rajotte-Julien
> EfficiOS
>

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      reply	other threads:[~2020-03-17  3:38 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-13 21:55 Rocky Dunlap via lttng-dev
2020-03-16 14:51 ` Jonathan Rajotte-Julien via lttng-dev
2020-03-17  3:38   ` Rocky Dunlap via lttng-dev [this message]

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