I don't know what:
event_thread = LLDBListenerThread(debugger)
does, but from your little sketch it looks like you are starting up a thread
listening on this debugger, and so far as I can see you destroy the debugger
out from under it without ever closing down that thread. That doesn't seem
like a good idea.
Jim
> On Feb 4, 2016, at 5:27 PM, Jeffrey Tan via lldb-dev
> <lldb-dev@lists.llvm.org> wrote:
>
> Hi,
>
> I am revising our lldb automation tests into async mode. However, I found it
> randomly crashes depends on timing. And the crash happens mostly while
> launching lldb twice in a row. I have narrowed down the code into a simple
> repro below. Any assumption I made wrong with the LLDB API here?
>
> The crash stack seems to be not consistently. In the small repro below, the
> crash stack is:
> Crashed Thread: 0 Dispatch queue: com.apple.main-thread
>
> Exception Type: EXC_BAD_ACCESS (SIGSEGV)
> Exception Codes: EXC_I386_GPFLT
>
> Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
> 0 _lldb.so 0x00000001088c7179
> EventMatcher::operator()(std::__1::shared_ptr<lldb_private::Event> const&)
> const + 21
> 1 _lldb.so 0x00000001088c65d2
> lldb_private::Listener::FindNextEventInternal(lldb_private::Broadcaster*,
> lldb_private::ConstString const*, unsigned int, unsigned int,
> std::__1::shared_ptr<lldb_private::Event>&, bool) + 176
> 2 _lldb.so 0x00000001088c6952
> lldb_private::Listener::WaitForEventsInternal(lldb_private::TimeValue const*,
> lldb_private::Broadcaster*, lldb_private::ConstString const*, unsigned int,
> unsigned int, std::__1::shared_ptr<lldb_private::Event>&) + 134
> 3 _lldb.so 0x00000001088c6ae9
> lldb_private::Listener::WaitForEventForBroadcasterWithType(lldb_private::TimeValue
> const*, lldb_private::Broadcaster*, unsigned int,
> std::__1::shared_ptr<lldb_private::Event>&) + 27
> 4 _lldb.so 0x0000000108abce6c
> lldb_private::Process::WaitForStateChangedEvents(lldb_private::TimeValue
> const*, std::__1::shared_ptr<lldb_private::Event>&, lldb_private::Listener*)
> + 112
> 5 _lldb.so 0x0000000108abcc95
> lldb_private::Process::WaitForProcessToStop(lldb_private::TimeValue const*,
> std::__1::shared_ptr<lldb_private::Event>*, bool, lldb_private::Listener*,
> lldb_private::Stream*) + 377
> 6 _lldb.so 0x0000000108ac516a
> lldb_private::Process::HaltForDestroyOrDetach(std::__1::shared_ptr<lldb_private::Event>&)
> + 216
> 7 _lldb.so 0x0000000108abc8b0
> lldb_private::Process::Destroy(bool) + 146
> 8 _lldb.so 0x0000000108abc56d
> lldb_private::Process::Finalize() + 91
> 9 _lldb.so 0x00000001088b63c4
> lldb_private::Debugger::Clear() + 148
> 10 _lldb.so 0x00000001088b61fd
> lldb_private::Debugger::Destroy(std::__1::shared_ptr<lldb_private::Debugger>&)
> + 37
> 11 _lldb.so 0x0000000106bdb144
> lldb::SBDebugger::Destroy(lldb::SBDebugger&) + 116
> 12 _lldb.so 0x0000000106c23daf
> _wrap_SBDebugger_Destroy(_object*, _object*) + 120
> 13 org.python.python 0x00000001058dd75f PyEval_EvalFrameEx +
> 12761
>
> while in the real unit test it is crashing at:
> Thread 12 Crashed:
> 0 libsystem_kernel.dylib 0x00007fff8635a286 __pthread_kill + 10
> 1 libsystem_c.dylib 0x00007fff919409b3 abort + 129
> 2 libc++abi.dylib 0x00007fff8a94ea21 abort_message + 257
> 3 libc++abi.dylib 0x00007fff8a9769d1
> default_terminate_handler() + 267
> 4 libobjc.A.dylib 0x00007fff935e77eb _objc_terminate() +
> 124
> 5 libc++abi.dylib 0x00007fff8a9740a1
> std::__terminate(void (*)()) + 8
> 6 libc++abi.dylib 0x00007fff8a973b30 __cxa_throw + 121
> 7 com.apple.LLDB.framework 0x000000010b994c6b
> std::__1::shared_ptr<lldb_private::Process>::shared_ptr<lldb_private::Process>(std::__1::weak_ptr<lldb_private::Process>
> const&, std::__1::enable_if<is_convertible<lldb_private::Process*,
> lldb_private::Process*>::value,
> std::__1::shared_ptr<lldb_private::Process>::__nat>::type) + 99
> 8 com.apple.LLDB.framework 0x000000010b8ac762
> lldb_private::Process::AppendSTDOUT(char const*, unsigned long) + 86
> 9 com.apple.LLDB.framework 0x000000010b6951d7
> lldb_private::Communication::ReadThread(void*) + 287
> 10 libsystem_pthread.dylib 0x00007fff8d92c05a _pthread_body + 131
> 11 libsystem_pthread.dylib 0x00007fff8d92bfd7 _pthread_start + 176
>
>
> ================Repro Code====================
>
> def wait_for_process_stop(process):
> while not process.is_stopped:
> time.sleep(0.1)
>
> def launch_debugging(debugger, stop_at_entry):
> error = lldb.SBError()
> listener = lldb.SBListener('Chrome Dev Tools Listener')
> target = debugger.GetSelectedTarget()
> process = target.Launch (listener,
> None, # argv
> None, # envp
> None, # stdin_path
> None, # stdout_path
> None, # stderr_path
> None, # working directory
> 0, # launch flags
> stop_at_entry, # Stop at entry
> error) # error
> print 'Launch result: %s' % str(error)
> event_thread = LLDBListenerThread(debugger)
> event_thread.start()
> return process
>
> def do_test():
> debugger = lldb.SBDebugger.Create()
> debugger.SetAsync(True)
> target = debugger.CreateTargetWithFileAndArch(executable_path,
> lldb.LLDB_ARCH_DEFAULT)
>
> process = launch_debugging(debugger, stop_at_entry=True)
>
> wait_for_process_stop(process) # wait for entry breakpoint.
> target.BreakpointCreateByName('main')
> process.Continue()
> wait_for_process_stop(process) # wait for main breakpoint.
> lldb.SBDebugger.Destroy(debugger)
>
> def main():
> do_test()
> do_test()
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