[regression] acceptance tests fails in ServerDisconnect.causes_client_to_terminate_by_default

[Daniel van Vugt]

This is happening in CI fairly frequently now:

8: [ RUN ] ServerDisconnect.causes_client_to_terminate_by_default
8: /tmp/buildd/mir-0.7.0+14.10.20140829bzr1884pkg0utopic412/tests/acceptance-tests/test_server_disconnect.cpp:229: Failure
8: Value of: client_results[0].signal
8: Actual: 9
8: Expected: 1
8: [ FAILED ] ServerDisconnect.causes_client_to_terminate_by_default (501 ms)

The offending EXPECT_EQ is one I added recently:
  EXPECT_EQ(SIGHUP, client_results[0].signal);

However the unreliability of the result shows the root cause of the problem really was pre-existing in wait_for_shutdown_client_processes().

[Daniel van Vugt (vanvugt)]

Signal 9 suggests we're killing the client prematurely (9 = SIGKILL) instead of waiting for it to die naturally.

[Daniel van Vugt (vanvugt)]

Weird. It looks like it should be using the default timeout of 60 seconds, yet it's receiving SIGKILL after only half a second.

[Alexandros Frantzis (afrantzis)]

Bumped priority to high as this problem is causing a significant number of CI failures.

[Kevin DuBois (kdub)]

So I poked around this bug today, I think that the kill signal is something valgrind is doing to dislodge a thread that it perceives as being blocked.

I cannot reproduce on my desktop running without valgrind, but can easily reproduce under valgrind running:
/usr/bin/valgrind --error-exitcode=1 --trace-children=yes --leak-check=full --show-leak-kinds=definite --errors-for-leak-kinds=definite bin/mir_acceptance_tests --gtest_filter="ServerDisconnect.causes_client_to_terminate_by_default" --gtest_repeat=10

(similar to what the CI infrastructure is doing)

[Kevin DuBois (kdub)]

also, if you turn on signal tracing in valgrind, all the failures have:

--13098-- sigvgkill for lwp 13099 tid 2

in common. (SIGVGKILL seems to be something valgrind has invented)

[PS Jenkins bot (ps-jenkins)]

Fix committed into lp:mir/devel at revision None, scheduled for release in mir, milestone Unknown

[Daniel van Vugt (vanvugt)]

P.S. the regression came from:

------------------------------------------------------------
revno: 1881 [merge]
author: Daniel van Vugt <email address hidden>
committer: Tarmac
branch nick: development-branch
timestamp: Mon 2014-09-01 04:53:25 +0000
message:
  When the server disconnects unexpectedly, give the client SIGHUP instead of
  the present SIGTERM. The former is more appropriate because it indicates:
    "Hangup detected on controlling terminal or death of controlling process"
    [signal(7)]
  whereas SIGTERM is reserved for more polite user-requested shutdowns.
  .

  Approved by PS Jenkins bot, Alexandros Frantzis, Kevin DuBois.
------------------------------------------------------------

[Launchpad Janitor (janitor)]

This bug was fixed in the package mir - 0.8.0+14.10.20141010-0ubuntu1

---------------
mir (0.8.0+14.10.20141010-0ubuntu1) utopic; urgency=medium

  [ Daniel van Vugt ]
  * New upstream release 0.8.0 (https://launchpad.net/mir/+milestone/0.8.0)
    - Enhancements:
      . Less sensitivity to ABI breaks - many headers unused by external
        projects are now hidden and not installed by -dev packaes. If you
        require any headers that are missing, just ask.
      . Touchspots: --enable-touchspots to servers; visually shows touch
        locations (warning: This affects performance LP: #1373692).
      . Client performance reporting: Any Mir client can now get accurate
        performance information (frame rate, render time, buffer lag etc)
        logged to stdout. Just set env MIR_CLIENT_PERF_REPORT=log
      . Further improved touch responsiveness, with less lag and smoother
        scrolling (so long as you don't enable touchspots).
      . Slightly faster builds using precompiled headers.
      . Turn hardware overlays on by default. When in use, this halves the
        CPU usage of a Mir server. Already enabled in unity-system-compositor.
      . More scripting to detect ABI breaks.
      . Improved src/ tree consistency (renamed "src/shared" to "src/common").
      . Improved fatal signal design: Changed from SIGTERM to SIGHUP delivered
        to clients on unexpected server disconnection.
      . Improved library/package design to allow concurrent installations
        of different Mir versions without conflicts.
      . Fd reception code is now common to client and server.
    - ABI summary: Servers need rebuilding, but clients do not;
      . Mirclient ABI unchanged at 8
      . Mircommon ABI bumped to 2
      . Mirplatform ABI bumped to 3
      . Mirserver ABI bumped to 26
    - API changes between Mir 0.7 and 0.8:
      . Lots of headers removed from the public SDK! We have only hidden
        headers not known to be used by any known projects. Please let us
        know if anything is missing - https://bugs.launchpad.net/mir/+filebug
      . graphics::Platform - interface changed significantly.
      . Lots of server API changes to support touchspots.
      . File descriptors now passed as type Fd instead of int32_t.
    - Bug fixes:
      . [regression] Mir deb packages with versioned names cannot be installed
        simultaneously any more (LP: #1293944)
      . A frozen client can hang the whole server (LP: #1350207)
      . QtMir FTBFS: fatal error: mir/input/input_channel.h: No such file or
        directory (LP: #1365934)
      . [regression] platform-api fails to build against Mir 0.8 (LP: #1368354)
      . Mir FTBFS with gcc 4.9.1-14 (utopic update):
        auto_unblock_thread.h:44:46: error: no matching function for call to
        ‘std::thread::thread(<brace-enclosed initializer list>)’ (LP: #1369389)
      . [regression] Compositing is jerky and stutters during touch events
        (LP: #1372850)
      . unit test fails: AndroidInputReceiverSetup.slow_raw_input_doesnt_cause_
        frameskipping (LP: #1373826)
      . intermittent hang in TestClientInput (LP: #1338612)
      . TestClientInput.scene_obscure_mo...

[Launchpad Janitor (janitor)]

This bug was fixed in the package mir - 0.8.0+14.10.20141005-0ubuntu1

---------------
mir (0.8.0+14.10.20141005-0ubuntu1) 14.09; urgency=medium

  [ Daniel van Vugt ]
  * New upstream release 0.8.0 (https://launchpad.net/mir/+milestone/0.8.0)
    - Enhancements:
      . Less sensitivity to ABI breaks - many headers unused by external
        projects are now hidden and not installed by -dev packaes. If you
        require any headers that are missing, just ask.
      . Touchspots: --enable-touchspots to servers; visually shows touch
        locations (warning: This affects performance LP: #1373692).
      . Client performance reporting: Any Mir client can now get accurate
        performance information (frame rate, render time, buffer lag etc)
        logged to stdout. Just set env MIR_CLIENT_PERF_REPORT=log
      . Further improved touch responsiveness, with less lag and smoother
        scrolling (so long as you don't enable touchspots).
      . Slightly faster builds using precompiled headers.
      . Turn hardware overlays on by default. When in use, this halves the
        CPU usage of a Mir server. Already enabled in unity-system-compositor.
      . More scripting to detect ABI breaks.
      . Improved src/ tree consistency (renamed "src/shared" to "src/common").
      . Improved fatal signal design: Changed from SIGTERM to SIGHUP delivered
        to clients on unexpected server disconnection.
      . Improved library/package design to allow concurrent installations
        of different Mir versions without conflicts.
      . Fd reception code is now common to client and server.
    - ABI summary: Servers need rebuilding, but clients do not;
      . Mirclient ABI unchanged at 8
      . Mircommon ABI bumped to 2
      . Mirplatform ABI bumped to 3
      . Mirserver ABI bumped to 26
    - API changes between Mir 0.7 and 0.8:
      . Lots of headers removed from the public SDK! We have only hidden
        headers not known to be used by any known projects. Please let us
        know if anything is missing - https://bugs.launchpad.net/mir/+filebug
      . graphics::Platform - interface changed significantly.
      . Lots of server API changes to support touchspots.
      . File descriptors now passed as type Fd instead of int32_t.
    - Bug fixes:
      . [regression] Mir deb packages with versioned names cannot be installed
        simultaneously any more (LP: #1293944)
      . A frozen client can hang the whole server (LP: #1350207)
      . QtMir FTBFS: fatal error: mir/input/input_channel.h: No such file or
        directory (LP: #1365934)
      . [regression] platform-api fails to build against Mir 0.8 (LP: #1368354)
      . Mir FTBFS with gcc 4.9.1-14 (utopic update):
        auto_unblock_thread.h:44:46: error: no matching function for call to
        ‘std::thread::thread(<brace-enclosed initializer list>)’ (LP: #1369389)
      . [regression] Compositing is jerky and stutters during touch events
        (LP: #1372850)
      . unit test fails: AndroidInputReceiverSetup.slow_raw_input_doesnt_cause_
        frameskipping (LP: #1373826)
      . intermittent hang in TestClientInput (LP: #1338612)
      . TestClientInput.scene_obscure_mot...