[ltt-dev] [UST] [bug] Problem colelcting traces of segmentation faults in an application

[shariyar (LTTng Project)]

Issue status update for
http://lttng.org/issue/241
Post a follow up:
http://lttng.org/comment/reply/241#comment-form


  Project:      Userspace Tracer (UST)
  Version:      0.11
  Component:    Code
  Category:     bug report
  Priority:     normal
  Assigned to:  Anonymous
  Status:       new
  Updated by:   shariyar

Hi,
I was using LTTng user-space library to collect function-call level
traces, but I found out that whenever there is a segmentation fault,
then LTTng does not collect traces. I am not sure where the problem is:
in LTTng tracer, or in another C library.


I was actually running an older version of gzip and I knew there is a
fault when the following command with the particular input file would be
run. I wanted to collect trace for this execution. The commands are:


usttrace -o /tmp/trace1/ ./gzip.exe -d < file8.z


I compiled gzip.exe with the following command:
gcc -g -finstrument-functions -DSTDC_HEADERS=1 -DHAVE_UNISTD_H=1
-DDIRENT=1 -DHAVE_ALLOCA_H=1  allfile.c -lust -rdynamic -o gzip.exe
cyg.o


Where cyg.o is a C program (file) that actually used the function
"backtrace_symbols" in "execinfo.h" to capture function names when the
program is executed.


Following are the errors that I found in the log file:
libust[30210/30215]: Error: Failed to receive message and fd (in
get_buf_shmid_pipe_fd() at libustconsumer.c:208)
libust[30210/30215]: Error: Failed to get buf_shmid and pipe_fd (in
connect_buffer() at libustconsumer.c:336)
libust[30210/30215]: Error: failed to connect to buffer (in
consumer_thread() at libustconsumer.c:578)
libust[30210/30217]: Warning: unable to connect to process, it probably
died before we were able to connect (in connect_buffer() at
libustconsumer.c:321)
libust[30210/30217]: Error: failed to connect to buffer (in
consumer_thread() at libustconsumer.c:578)
libust[30210/30216]: Warning: unable to connect to process, it probably
died before we were able to connect (in connect_buffer() at
libustconsumer.c:321)
libust[30210/30216]: Error: failed to connect to buffer (in
consumer_thread() at libustconsumer.c:578)
libust[30210/30218]: Warning: unable to connect to process, it probably
died before we were able to connect (in connect_buffer() at
libustconsumer.c:321)
libust[30210/30218]: Error: failed to connect to buffer (in
consumer_thread() at libustconsumer.c:578)


How could this problem be solved in LTTng?


Regards,
Shariyar



shariyar