We’ve got a new crash in our app. The GC thread is...

# kotlin-native

[jessewilson]

We’ve got a new crash in our app. The GC thread is crashing, possibly due to an interaction between the GC and reference counting on iOS.

EXC_BAD_ACCESS: Attempted to dereference garbage pointer 0x28.

0 Cash +0x56510b4                 kotlin::gc::ParallelMarkConcurrentSweep::mainGCThreadBody()
1 Cash +0x564fc7c                 void* std::__1::__thread_proxy<std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct> >, void (*)(kotlin::ScopedThread::attributes, (anonymous namespace)::createGCThread<kotlin::gc::ParallelMarkConcurrentSweep::ParallelMarkConcurrentSweep(kotlin::alloc::Allocator&, kotlin::gcScheduler::GCScheduler&, bool, unsigned long)::$_1>(char const*, kotlin::gc::ParallelMarkConcurrentSweep::ParallelMarkConcurrentSweep(kotlin::alloc::Allocator&, kotlin::gcScheduler::GCScheduler&, bool, unsigned long)::$_1&&)::{lambda()#1}&&), kotlin::ScopedThread::attributes, (anonymous namespace)::createGCThread<kotlin::gc::ParallelMarkConcurrentSweep::ParallelMarkConcurrentSweep(kotlin::alloc::Allocator&, kotlin::gcScheduler::GCScheduler&, bool, unsigned long)::$_1>(char const*, kotlin::gc::ParallelMarkConcurrentSweep::ParallelMarkConcurrentSweep(kotlin::alloc::Allocator&, kotlin::gcScheduler::GCScheduler&, bool, unsigned long)::$_1&&)::{lambda()#1}> >(void*)
2 libsystem_pthread.dylib +0x2a8c __pthread_start

I reported this in YouTrack as KT-68769. I’m attempting to reproduce the crash but I haven’t yet! (Though I’m getting good diagnostics from Bugsnag.)