https://bugs.launchpad.net/percona-toolkit/+bug/1320168

We use the pt-pmp (a variety for pmp !http://poormansprofiler.org/! by Percona ) tool a lot to analyze our online MySQL problem.

But when we execute the pmp, we have found  tps/qps of mysqld drop a lot, such as:

[10225s] threads: 256, tps: 8738.19, reads/s: 0.00, writes/s: 8735.39 [10230s] threads: 256, tps: 8749.81, reads/s: 0.00, writes/s: 8745.21 [10235s] threads: 256, tps: 8757.80, reads/s: 0.00, writes/s: 8763.00 [10240s] threads: 256, tps: 8772.80, reads/s: 0.00, writes/s: 8766.40 [10245s] threads: 256, tps: 284.80, reads/s: 0.00, writes/s: 278.40 [10250s] threads: 256, tps: 8036.65, reads/s: 0.00, writes/s: 8038.85 [10255s] threads: 256, tps: 8772.41, reads/s: 0.00, writes/s: 8773.01  We modify the code of pt-pmp to fix it. The patch is below:

143,148d142
< if gdb -nx --quiet --batch --readnever > /dev/null
 
 2>&1; then
<     readnever=--readnever
< else
<     readnever=
< fi
<
205c199
<          gdb $readnever -ex "set pagination 0" -ex "thread apply all bt" -batch -p $OPT_p >> "${OPT_k:-$TMPDIR/percona-toolkit}"
---
>          gdb -ex "set pagination 0" -ex "thread apply all bt
 
" -batch -p $OPT_p >> "${OPT_k:-$TMPDIR/percona-toolkit}"