Comments on: Poor man’s contention profiling

By: Mark Callaghan

Mark Callaghan — Wed, 18 Feb 2009 18:40:42 +0000

I modified the script to prepend the thread id to each comma-separated stack so that I can only look at traces for specific threads. This works great as I want to know where a thread spends all time (CPU, blocked on mutex, blocked on IO).

By: Mark Callaghan

Mark Callaghan — Sun, 15 Feb 2009 18:35:57 +0000

And the full script
# mpid = mysqld pid
mpid=15739 ; nsamples=1; sleeptime=1;
for x in $( seq 0 $nsamples) ; do
gdb -ex “set pagination 0″ -ex “thread apply all bt” –batch -p $mpid
sleep $sleeptime
done | \
awk ‘BEGIN { s = “”; } /Thread/ { print s; s = “”; } /^\#/ { if (s != “” ) { s = s “,” $4} else { s = $4 } } END { print s }’ – | \
sort | uniq -c | sort -r -n -k 1,1

By: Mark Callaghan

Mark Callaghan — Sun, 15 Feb 2009 18:27:34 +0000

Collapse the call stacks into strings with this:
BEGIN { s = “”; }
/Thread/ { print s; s = “”; }
/^\#/ { if (s != “” ) { s = s “,” $4} else { s = $4 } }
END { print s }

And then aggregate the result with: ’sort | uniq -c’

By: Mark Callaghan

Mark Callaghan — Sun, 15 Feb 2009 18:07:01 +0000

Domas,
You need to share the 20 lines of Perl/Python/Awk.