pt-stalk before_collect triggers will not fire when --no-collect is specified

[David]

This is more likely a feature request than a bug, but the before_collect triggers do not fire when threshold + cycles = fire , but only if the collect process itself is invoked , which could be interpreted to contradict to what is specified in the documentation:

"before_collect

Called when the trigger occurs, before running a --collect subprocesses in the background."

I would like to leverage pt-stalk to do some ad-hoc specific monitoring of custom counts (via the --function option) and then collect some custom data (via --plugins) without dumping all of the data collected by pt-stalk

Details -

plugin :

From the example page :

before_collect() {
   touch /tmp/foo
}

Log output for failed trigger fire:

2015_08_26_10_06_44 Starting /mysql/software/pt/bin/pt-stalk --function=./pt_stalk_user --variable=Threads_running --threshold=1 --match= --cycles=5 --interval=10 --iterations= --run-time=30 --sleep=5 --dest=/var/lib/pt-stalk --prefix= --notify-by-email= --log=./pt-stalk.log --pid=./pid --plugin=./pt_stalk_collect
2015_08_26_10_06_44 Not running with root privileges!
2015_08_26_10_06_44 Check results: ./pt_stalk_user(Threads_running)=2, matched=yes, cycles_true=1
2015_08_26_10_06_54 Check results: ./pt_stalk_user(Threads_running)=2, matched=yes, cycles_true=2
2015_08_26_10_07_04 Check results: ./pt_stalk_user(Threads_running)=2, matched=yes, cycles_true=3
2015_08_26_10_07_14 Check results: ./pt_stalk_user(Threads_running)=2, matched=yes, cycles_true=4
2015_08_26_10_07_24 Check results: ./pt_stalk_user(Threads_running)=2, matched=yes, cycles_true=5
2015_08_26_10_07_24 Collect 1 triggered
2015_08_26_10_07_24 Collect 1 done

Log output for successful trigger-fire:

2015_08_26_10_10_21 Starting /mysql/software/pt/bin/pt-stalk --function=./pt_stalk_user --variable=Threads_running --threshold=1 --match= --cycles=5 --interval=10 --iterations= --run-time=30 --sleep=5 --dest=. --prefix= --notify-by-email= --log=./pt-stalk.log --pid=./pid --plugin=./pt_stalk_collect
2015_08_26_10_10_21 Not running with root privileges!
2015_08_26_10_10_21 Check results: ./pt_stalk_user(Threads_running)=2, matched=yes, cycles_true=1
2015_08_26_10_10_31 Check results: ./pt_stalk_user(Threads_running)=2, matched=yes, cycles_true=2
2015_08_26_10_10_41 Check results: ./pt_stalk_user(Threads_running)=2, matched=yes, cycles_true=3
2015_08_26_10_10_51 Check results: ./pt_stalk_user(Threads_running)=2, matched=yes, cycles_true=4
2015_08_26_10_11_01 Check results: ./pt_stalk_user(Threads_running)=2, matched=yes, cycles_true=5
2015_08_26_10_11_01 Collect 1 triggered
2015_08_26_10_11_01 Collect 1 PID 26643
2015_08_26_10_11_01 Collect 1 done

The log in example one says that the 'Collect 1 " event is triggered, but must then branch when encountering the "--no-collect' option, before parsing any plugin files

It is a small thing, but it would be useful!

Thanks!

[Nilnandan Joshi (nilnandan-joshi)]

Confirmed as a feature request.

root@desktop:/usr/bin# cat pt-stalk | head -1104 | tail -4
before_collect() {
   :
touch /tmp/foo
}
root@desktop:/usr/bin#

nilnandan@desktop:~/Downloads/pt-stalk$ sudo pt-stalk --no-stalk --threshold=1 --cycles=5
[sudo] password for nilnandan:
2015_08_28_13_13_39 Starting /usr/bin/pt-stalk --function=status --variable=Threads_running --threshold=1 --match= --cycles=0 --interval=1 --iterations= --run-time=30 --sleep=300 --dest=/var/lib/pt-stalk --prefix= --notify-by-email= --log=/var/log/pt-stalk.log --pid=/var/run/pt-stalk.pid --plugin=
2015_08_28_13_13_39 Not stalking; collect triggered immediately
2015_08_28_13_13_39 Collect 1 triggered
2015_08_28_13_13_39 Collect 1 PID 8985
2015_08_28_13_13_39 Collect 1 done
2015_08_28_13_13_39 Sleeping 300 seconds after collect
^C2015_08_28_13_13_45 Caught signal, exiting
2015_08_28_13_13_45 All subprocesses have finished
2015_08_28_13_13_45 Exiting because OKTORUN is false
2015_08_28_13_13_45 /usr/bin/pt-stalk exit status 1
nilnandan@desktop:~/Downloads/pt-stalk$

nilnandan@desktop:/tmp$ ll foo
-rw-r--r-- 1 root root 0 Aug 28 13:13 foo
nilnandan@desktop:/tmp$

nilnandan@desktop:~/Downloads/pt-stalk$ sudo pt-stalk --no-stalk --threshold=1 --cycles=5 --no-collect
2015_08_28_13_14_53 Starting /usr/bin/pt-stalk --function=status --variable=Threads_running --threshold=1 --match= --cycles=5 --interval=1 --iterations= --run-time=30 --sleep=300 --dest=/var/lib/pt-stalk --prefix= --notify-by-email= --log=/var/log/pt-stalk.log --pid=/var/run/pt-stalk.pid --plugin=
^C2015_08_28_13_17_43 Caught signal, exiting
2015_08_28_13_17_43 All subprocesses have finished
2015_08_28_13_17_43 Exiting because OKTORUN is false
2015_08_28_13_17_44 /usr/bin/pt-stalk exit status 1
nilnandan@desktop:~/Downloads/pt-stalk$

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PT-1301