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From: Jonathan Rajotte-Julien via lttng-dev <lttng-dev@lists.lttng.org>
To: Eqbal <eqbalzee@gmail.com>
Cc: lttng-dev@lists.lttng.org
Subject: Re: [lttng-dev] lttng live event loss with babeltrace2
Date: Fri, 7 May 2021 14:05:32 -0400	[thread overview]
Message-ID: <20210507180532.GA1227214@joraj-alpa> (raw)
In-Reply-To: <CAPj=WkjEZN+_NgrnF3djfF_jCyp+D195e+KpzqzAK9kfmrTu6Q@mail.gmail.com>

Hi,

See https://github.com/lttng/lttng-tools/commit/c876d657fb08a91ca7c907b92f1b7604aee664ee . 

We would appreciate your feedback on this if possible based on your use case.

Cheers

On Mon, May 03, 2021 at 05:05:10PM -0700, Eqbal via lttng-dev wrote:
> Hi,
> 
> I have a lttng live session trace consumer application using libbabeltrace2
> where I create a graph to consume lttng live session traces and output to
> another sink. I am running the graph in a loop at some polling interval as
> long as I get BT_GRAPH_RUN_STATUS_AGAIN status. What I am noticing is that
> if my polling interval is large enough I tend to lose either all or some of
> the events. I experimented with various polling intervals and it seems if
> the polling interval is less than *DELAYUS *from "lttng-create
> --live=DELAYUS" option then I am able to get all the events, otherwise I
> tend to lose events.
> 
> Here are the steps I follow:
> 1. start session daemon and relay daemon
> 2. create a live session (with default delay of 1s), enable events and start
> 3. Start my application (hello world example from lttng docs)
> 4. Start the consumer application built using libbabeltrace that connects
> to the live session
> 
> I noticed that the events are actually persisted in the ~/lttng-traces by
> the relay daemon, but it does not reach babeltrace consumer application. I
> have noticed the same behavior with babeltrace2 cli.
> 
> I would like to understand what is the reason for such behavior and if
> playing with the polling interval in relation to the DELAYUS value is the
> right thing to do.
> 
> Thanks,
> Eqbal

> _______________________________________________
> lttng-dev mailing list
> lttng-dev@lists.lttng.org
> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev


-- 
Jonathan Rajotte-Julien
EfficiOS
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  parent reply	other threads:[~2021-05-07 18:05 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-04  0:05 Eqbal via lttng-dev
2021-05-04 13:16 ` Jonathan Rajotte-Julien via lttng-dev
2021-05-04 14:44 ` Jonathan Rajotte-Julien via lttng-dev
2021-05-07 18:05 ` Jonathan Rajotte-Julien via lttng-dev [this message]
2021-05-11  0:35   ` Eqbal via lttng-dev
2021-05-11  1:14     ` Jonathan Rajotte-Julien via lttng-dev

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