[lttng-dev] SIG33 message

[Sebastien Boisvert]

Hi Mosleh,

(I just saw Mathieu's answer arrive in my inbox while I was writing this.)

First, I don't know the exact solution.


In Linux, signals are sent with the kill() function.

In the LTTng-UST source code, there are 3 signals that relate to 'Suspended: Signal: SIG33:Real-time event 33' (RT):

libringbuffer/ring_buffer_frontend.c:82:#define LTTNG_UST_RB_SIG_FLUSH		SIGRTMIN
libringbuffer/ring_buffer_frontend.c:83:#define LTTNG_UST_RB_SIG_READ		SIGRTMIN + 1
libringbuffer/ring_buffer_frontend.c:84:#define LTTNG_UST_RB_SIG_TEARDOWN	SIGRTMIN + 2

=> http://git.lttng.org/?p=lttng-ust.git;a=blob;f=libringbuffer/ring_buffer_frontend.c;h=9721df1634585f028316d13f96b184af7e99cc08;hb=HEAD#l82


On my system (Ubuntu 18.04.2 LTS with Linux 4.15.0-47-generic), SIGRTMIN = 34.

Check with 'kill -l SIGRTMIN' on your system to see if it it the same value.



In the LTTng-UST source code, there 1 this call to kill():

libringbuffer/ring_buffer_frontend.c:767:	kill(getpid(), LTTNG_UST_RB_SIG_TEARDOWN);

=> http://git.lttng.org/?p=lttng-ust.git;a=blob;f=libringbuffer/ring_buffer_frontend.c;h=9721df1634585f028316d13f96b184af7e99cc08;hb=HEAD#l767




These custom signals seem to be handled here:

libringbuffer/ring_buffer_frontend.c:660

=>  http://git.lttng.org/?p=lttng-ust.git;a=blob;f=libringbuffer/ring_buffer_frontend.c;h=9721df1634585f028316d13f96b184af7e99cc08;hb=HEAD#l660




On 2019-04-04 3:26 p.m., Mosleh Uddin wrote:
> Hello,
> 
> I am building an application which I am compiling with the 'lttng-ust' flag. When I try to debug the application using gdb, I get a 'Suspended: Signal: SIG33:Real-time event 33' message. This only happens when I compile with the 'lttng-ust' flag, if I remove it I no longer have this issue. Any insight?
> 
> Regards,
> Mosleh
> 
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