intermittent acceptance test bug in TestClientInput

[Alan Griffiths]

https://jenkins.qa.ubuntu.com/job/mir-clang-utopic-amd64-build/2344/console

        Start 34: mir_acceptance_tests.TestClientInput.*
 34/246 Test #34: mir_acceptance_tests.TestClientInput.* ........................................***Failed 15.85 sec

Similar to lp: 1196744 but that was closed a year ago. (So I'm assuming it hasn't been seen all this time and we have a new cause.)

[Alan Griffiths (alan-griffiths)]

I've spent a while looking at this and found nothing convincing.

Running it locally - under valgrind, on a loaded system, for a long time - doesn't help reproduce.

helgrind reports a number of errors around expectations - but many of these seem to be because the thread fulfilling the expectation is running before the expectation is set. There is sequencing (by only sending events from the server after setting expectations) but streaming data over a socket goes beyond the "memory model" and helgrind doesn't see it.

I've changed the tests to start the client thread after the expectations are set - which more than halves the size of the helgrind report.

[PS Jenkins bot (ps-jenkins)]

Fix committed into lp:mir at revision None, scheduled for release in mir, milestone 0.9.0