Bug #1010

When babeltrace (and lttng view) output is redirected from stdout while receiving live traces it does not print events as they come in (using > not --output since --output doesn't work)

Added by Leo Jweda about 4 years ago. Updated about 4 years ago.

Target version:
Start date:
Due date:
% Done:


Estimated time:


Components involved: babeltrace and lttngview
Component version: How do you get babeltrace's version!? LTTng version: 2.6.0
System information: Linux leojweda-VirtualBox 4.2.0-35-generic #40-Ubuntu SMP Tue Mar 15 22:15:45 UTC 2016 x86_64 x86_64 GNU/Linux
Expected results: When running "lttng view > someFile" the events get written to the file as they come in. See how redirecting output to a file works with ping.
Actual results: The events get dumped to the file after about a minute or two, or when the session ends. It works fine if the output is left to stdout.
Steps to reproduce:

lttng create Failover --live
lttng start

(in a different terminal)

lttng view


Updated by Mathieu Desnoyers about 4 years ago

You appear to have missed the "enable-event" step, which means there is nothing traced. Therefore, lttng view is sitting there awaiting for events, but none are produced.


Updated by Leo Jweda about 4 years ago

My apologies. We use

lttng enable-event -u -all

just before lttng start.

We will post a video of the behaviour and how to reproduce shortly.


Updated by Leo Jweda about 4 years ago

Here's a video of how to reproduce the bug, the expected results, and the actual results:


Updated by Mathieu Desnoyers about 4 years ago

  • Status changed from New to Resolved
  • % Done changed from 0 to 100

Applied in changeset babeltrace:babeltrace|commit:220e0cbec97669ccfe4ed8a7e69c73c9ac72062d.

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