Crash switching back to app — mbgl::Channel<mbgl::Worker::work>::send()

[1ec5]

The iOS demo app often crashes when switching away from the app while it’s animating then switching back to the app:

Map (190)#0 0x00000001932c53f0 in __cxa_throw ()
#1  0x0000000193298c78 in std::__1::__throw_system_error(int, char const*) ()
#2  0x0000000100352210 in std::__1::unique_lock<std::__1::mutex>::unique_lock(std::__1::mutex&) [inlined] at /Applications/Xcode+1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/__mutex_base:108
#3  0x00000001003521e8 in std::__1::unique_lock<std::__1::mutex>::unique_lock(std::__1::mutex&) [inlined] at /Applications/Xcode+1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/__mutex_base:108
#4  0x00000001003521dc in mbgl::Channel<mbgl::Worker::Work>::send(mbgl::Worker::Work const&) at /Users/mxn/hub/mapbox-gl-native-2/src/mbgl/util/channel.hpp:16
#5  0x0000000100350de0 in mbgl::Worker::send(std::__1::function<void ()>, std::__1::function<void ()>) at /Users/mxn/hub/mapbox-gl-native-2/src/mbgl/util/worker.cpp:41
#6  0x0000000100178568 in mbgl::TileData::reparse(mbgl::Worker&, std::__1::function<void ()>) at /Users/mxn/hub/mapbox-gl-native-2/src/mbgl/map/tile_data.cpp:62
#7  0x000000010017c74c in mbgl::TileData::request(mbgl::Worker&, float, std::__1::function<void ()>)::$_0::operator()(mbgl::Response const&) const at /Users/mxn/hub/mapbox-gl-native-2/src/mbgl/map/tile_data.cpp:46
#8  0x000000010017c2b0 in decltype(std::__1::forward<mbgl::TileData::request(mbgl::Worker&, float, std::__1::function<void ()>)::$_0&>(fp)(std::__1::forward<mbgl::Response const&>(fp0))) std::__1::__invoke<mbgl::TileData::request(mbgl::Worker&, float, std::__1::function<void ()>)::$_0&, mbgl::Response const&>(mbgl::TileData::request(mbgl::Worker&, float, std::__1::function<void ()>)::$_0&&&, mbgl::Response const&&&) [inlined] at /Applications/Xcode+1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/__functional_base:413
#9  0x000000010017c290 in std::__1::__function::__func<mbgl::TileData::request(mbgl::Worker&, float, std::__1::function<void ()>)::$_0, std::__1::allocator<mbgl::TileData::request(mbgl::Worker&, float, std::__1::function<void ()>)::$_0>, void (mbgl::Response const&)>::operator()(mbgl::Response const&) at /Applications/Xcode+1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/functional:1370
#10 0x000000010023a2f4 in std::__1::function<void (mbgl::Response const&)>::operator()(mbgl::Response const&) const at /Applications/Xcode+1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/functional:1756
#11 0x0000000100239470 in mbgl::Request::invoke() at /Users/mxn/hub/mapbox-gl-native-2/src/mbgl/storage/request.cpp:57
#12 0x000000010023927c in mbgl::Request::notifyCallback() at /Users/mxn/hub/mapbox-gl-native-2/src/mbgl/storage/request.cpp:38
#13 0x000000010023a19c in mbgl::Request::Request(mbgl::Resource const&, uv_loop_s*, mbgl::Environment const&, std::__1::function<void (mbgl::Response const&)>)::$_0::operator()(uv_async_s*, int) const at /Users/mxn/hub/mapbox-gl-native-2/src/mbgl/storage/request.cpp:27
#14 0x000000010023a134 in mbgl::Request::Request(mbgl::Resource const&, uv_loop_s*, mbgl::Environment const&, std::__1::function<void (mbgl::Response const&)>)::$_0::__invoke(uv_async_s*, int) at /Users/mxn/hub/mapbox-gl-native-2/src/mbgl/storage/request.cpp:27
#15 0x00000001003c5ab0 in uv__async_event at /Users/kkaefer/Code/mason/libuv-0.10.28/mason_packages/.build/libuv-0.10.28/src/unix/async.c:80
#16 0x00000001003c5ed4 in uv__async_io at /Users/kkaefer/Code/mason/libuv-0.10.28/mason_packages/.build/libuv-0.10.28/src/unix/async.c:156
#17 0x00000001003e2564 in uv__io_poll at /Users/kkaefer/Code/mason/libuv-0.10.28/mason_packages/.build/libuv-0.10.28/src/unix/kqueue.c:233
#18 0x00000001003c6630 in uv_run at /Users/kkaefer/Code/mason/libuv-0.10.28/mason_packages/.build/libuv-0.10.28/src/unix/core.c:317
#19 0x0000000100129990 in mbgl::Map::run() at /Users/mxn/hub/mapbox-gl-native-2/src/mbgl/map/map.cpp:278
#20 0x000000010013a6c8 in mbgl::Map::start(bool)::$_5::operator()() const at /Users/mxn/hub/mapbox-gl-native-2/src/mbgl/map/map.cpp:177
#21 0x000000010013a4b0 in decltype(std::__1::forward<mbgl::Map::start(bool)::$_5>(fp)(std::__1::forward<>(fp0))) std::__1::__invoke<mbgl::Map::start(bool)::$_5>(mbgl::Map::start(bool)::$_5&&) [inlined] at /Applications/Xcode+1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/__functional_base:413
#22 0x000000010013a4a4 in void std::__1::__thread_execute<mbgl::Map::start(bool)::$_5>(std::__1::tuple<mbgl::Map::start(bool)::$_5>&, std::__1::__tuple_indices<>) [inlined] at /Applications/Xcode+1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/thread:332
#23 0x000000010013a494 in void* std::__1::__thread_proxy<std::__1::tuple<mbgl::Map::start(bool)::$_5> >(void*) at /Applications/Xcode+1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/thread:342
#24 0x000000019430fdc8 in _pthread_body ()
#25 0x000000019430fd24 in _pthread_start ()

worker appears to be bogus by the time mbgl::TileData::reparse() is called.

[1ec5]

https://rink.hockeyapp.net/manage/apps/163490/app_versions/10/crash_reasons/32272438

[kkaefer]

The Worker object has been destructed when it's called.

[jfirebaugh]

Should I be able to reproduce this in the simulator?

[1ec5]

Should be able to.

[jfirebaugh]

VectorTileData outlives its worker when it hasn't done style.reset() by the time backgrounding the app ⇢ Map::stop ⇢ asyncTerminate ⇢ workers.reset() occurs. In that case, the style is being retained by the tile, so sources and all the tiles are also retained (cycle), and any pending requests can still be fulfilled, but the workers are gone.

The reference cycle is causing us huge problems, we have to break that.

[jfirebaugh]

This will be fixed by #1065.