Bug #574
closed
lttng 2.2.0-rc2: reliable crash
Added by Daniel U. Thibault almost 11 years ago.
Updated over 10 years ago.
Description
Here is a reliable way of crashing LTTng:
$ sudo -H lttng create sss
Session sss created.
Traces will be written in /root/lttng-traces/sss-20130625-103225
$ sudo -H lttng enable-channel u0 -u --buffers-uid
UST channel u0 enabled for session sss
$ sudo -H lttng enable-channel k0 -k
Kernel channel k0 enabled for session sss
$ sudo -H lttng start
Tracing started for session sss
$ sudo -H lttng stop
Waiting for data availability
Tracing stopped for session sss
$ sudo -H lttng enable-channel u4 -u --buffers-uid
UST channel u4 enabled for session sss
$ sudo -H lttng start
Tracing started for session sss
$ sudo -H lttng enable-channel u6 -u --buffers-uid --subbuf-size 4096
UST channel u6 enabled for session sss
$ sudo -H lttng stop
At which point LTTng hangs and must be killed manually. Once the session daemon is killed, the "Waiting for data availability" message appears, followed by an awful lot of periods.
I'm using:
lttng-modules-2.2.0-rc2-11-5ca7b8a
lttng-tools 2.2.0-rc2-73-51fedb7
lttng-ust-2.2.0-rc2-34-76aca78
userspace-rcu-0.7.6-50-2f49a49
Files
bug-574.txt (27.2 KB)
bug-574.txt |
lttng-sessiond -vvv ---verbose-consumer |
Daniel U. Thibault, 06/25/2013 01:26 PM
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I'm unable to reproduce this issue with the exact same command.
Do you have any applications running during that test ?
Also, can you provide the logs of the session daemon with "-vvv --verbose-consumer". That would be very helpful since I can't reproduce that :S.
- Status changed from New to Confirmed
- Assignee set to David Goulet
It has been reproduced on Christian computer. We are hunting this one down!
Attached is my capture of the session daemon output.
- Assignee deleted (
David Goulet)
- Target version changed from 2.2 to 2.3
This affects lttng-modules HEAD master.
lttng-modules-2.2.0-rc2-11-5ca7b8a --> "5ca7b8a" is a commit from master and not the 2-2.0-rc2 tag.
Tagging this for 2.3 since it's an issue added for the next 2.3 release (in master branch).
Simplified script to reproduce:
lttng create sss
sleep 2
lttng enable-channel k0 -k
sleep 2
lttng start
sleep 2
lttng stop
sleep 2
lttng start
sleep 2
lttng stop
sleep 2
It only occurs with master branch of lttng-modules. This is 2.3 material.
- Assignee set to Julien Desfossez
commit:
commit d83004aa718065e5221d8ef4b99e4302b70b3df9
Author: Julien Desfossez <jdesfossez@efficios.com>
Date: Thu Jun 6 16:38:48 2013 -0400
Metadata cache and multiple metadata channels
Implement a cache for the kernel metadata and a list of metadata
channels.
When new metadata is appended, all metadata channels are awakened so
they can return from poll and get the newly added metadata
This allows to request the metadata multiple times by creating multiple
metadata channels (useful for snapshots).
With this new feature, the poll and get_subbuf ring buffer operations
are now overridden by lttng-abi for the metadata channels, to check the
cache before doing these operations.
Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
is very likely the cause of this issue.
- Project changed from LTTng-tools to LTTng-modules
- Status changed from Confirmed to Resolved
- Assignee changed from Julien Desfossez to Mathieu Desnoyers
Resolved by commit:
commit 9de2c21569afcb6b983e81a2e9b1d0c2b83c98f0
Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed Jun 26 13:55:31 2013 -0400
Fix: don't do 0 byte event reservation
Caused sequence of:
lttng create
lttng enable-event -k sched_switch
lttng start
lttng stop
lttng start
lttng stop
to hang on waiting for data......
Issue appeared in
commit d83004aa718065e5221d8ef4b99e4302b70b3df9
Author: Julien Desfossez <jdesfossez@efficios.com>
Date: Thu Jun 6 16:38:48 2013 -0400
Metadata cache and multiple metadata channels
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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