Commit 49e64768 authored by Gregory Szorc's avatar Gregory Szorc
Browse files

Bug 1272782 - Wait longer and stop after "done" message; r=ahal 

Before, we kept waiting for data in the pipe after receiving the
"done" message. This didn't really make much sense because the
"done" message should be the final thing sent over the pipe!

e9113fd6cdb8 (bug 1239939) recently dropped the poll interval
of the pipe from 1.0 to 0.1s. This appears to have introduced
an intermittent failure in a test. The race condition was
between the child process sending data and the parent process
timing out (after only 0.1s) waiting for that data. Increasing
the timeout makes the failure reproduce less often. Although
technically the race condition is still present! I'm not
inclined to fix it at this time, however.

The rationale for dropping the pipe timeout was that it was
causing lag when terminating short-lived processes. Now that
we abort the pipe reading/polling loop as soon as the "done"
message is received, we no longer poll the pipe after receiving
"done" and no longer have to worry about its timeout impacting
shutdown time.

MozReview-Commit-ID: EeENQ95RAs1

--HG--
extra : rebase_source : ce2502f32841a55f912aafdba7cc81e3a58e3ff5
parent 4b05251a

testing/mozbase/mozsystemmonitor/mozsystemmonitor/resourcemonitor.py

+8 −2
Original line number Diff line number Diff line
@@ -290,13 +290,19 @@ class SystemResourceMonitor(object): 


        done = False



        while self._pipe.poll(0.1):

        # The child process will send each data sample over the pipe

        # as a separate data structure. When it has finished sending

        # samples, it sends a special "done" message to indicate it

        # is finished.

        while self._pipe.poll(1.0):

            start_time, end_time, io_diff, cpu_diff, cpu_percent, virt_mem, \

                swap_mem = self._pipe.recv()



            # There should be nothing after the "done" message so

            # terminate.

            if start_time == 'done':

                done = True

                continue

                break



            io = self._io_type(*io_diff)

            virt = self._virt_type(*virt_mem)