[Lldb-commits] [PATCH] fix lldb-mi hang on OSX

Tue Dec 2 02:08:47 PST 2014

I will test your patch further on Linux and Windows. If it does not break anything
and we don't hear any other objection then I will commit it.

Thanks,
Abid

> -----Original Message-----
> From: dawn at burble.org [mailto:dawn at burble.org]
> Sent: 02 December 2014 09:58
> To: Abid, Hafiz
> Cc: colin at codeplay.com; deepak at codeplay.com; lldb-commits at cs.uiuc.edu
> Subject: Re: [Lldb-commits] [PATCH] fix lldb-mi hang on OSX
> 
> Thank you for reviewing!
> 
> On Fri, Nov 28, 2014 at 10:02:33AM +0000, Abid, Hafiz wrote:
> > Hi Dawn,
> > I looked at the patch a bit. It looks ok to use select to check if the input is
> available before blocking on fgets. But I am still wondering why you need
> extra "return" in case of -exec-run. It seems to work ok on Linux. Where is it
> blocking in OSX? Btw, if the problem is only with gdb-exit then an extra check
> for it where we check for "quit" will work too.
> 
> I can't explain why it works on Linux (although I assumed it must), but on
> OSX, if you attach you'll see that it is waiting on a mutex.  You can see where
> in the following example:
> 
> debug session in lldb-mi showing hang after -exec-run:
>     yippie:~/llvm_trunk$$LLDBMI_EXEC --interpreter
>     (gdb)
>     -file-exec-and-symbols ~/tmp/a.out
>     ^done
>     -break-insert -f main
>     =breakpoint-
> modified,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",ad
> dr="0xffffffff",func="main",file="x.cpp",fullname="/Users/dawn/tmp/x.cpp",li
> ne="5",pending=["main"],times="0",original-location="main"}
> 
> ^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr=
> "0xffffffff",func="main",file="x.cpp",fullname="/Users/dawn/tmp/x.cpp",line=
> "5",pending=["main"],times="1",original-location="main"}
>     -exec-run
> 
> attaching to lldb-mi to see what's up:
>     yippie:~/cppstd/source$~/llvm_delphi/build_ninja/bin/lldb
>     (lldb) attach 27893
>     Process 27893 stopped
>     * thread #1: tid = 0xf7a813, 0x00007fff90dad746
> libsystem_kernel.dylib`__psynch_mutexwait + 10, queue = 'com.apple.main-
> thread', stop reason = signal SIGSTOP
> 	frame #0: 0x00007fff90dad746
> libsystem_kernel.dylib`__psynch_mutexwait + 10
>     -> 0x7fff90dad746 <__psynch_mutexwait+10>: jae    0x7fff90dad750
> ; __psynch_mutexwait + 20
>     0x7fff90dad748 <__psynch_mutexwait+12>: movq   %rax, %rdi
>     0x7fff90dad74b <__psynch_mutexwait+15>: jmp    0x7fff90daa175            ;
> cerror_nocancel
>     0x7fff90dad750 <__psynch_mutexwait+20>: retq
> 
>     Executable module set to "/Users/dawn/llvm_trunk/build_ninja/bin/lldb-
> mi".
>     Architecture set to: x86_64-apple-macosx.
>     (lldb) bt
>     * thread #1: tid = 0xf7a813, 0x00007fff90dad746
> libsystem_kernel.dylib`__psynch_mutexwait + 10, queue = 'com.apple.main-
> thread', stop reason = signal SIGSTOP
>     * frame #0: 0x00007fff90dad746
> libsystem_kernel.dylib`__psynch_mutexwait + 10
> 	frame #1: 0x00007fff8f51b779
> libsystem_pthread.dylib`_pthread_mutex_lock + 372
> 	frame #2: 0x00007fff92ea5edd libsystem_c.dylib`flockfile + 37
> 	frame #3: 0x00007fff92ea6e74 libsystem_c.dylib`fileno + 15
> 	frame #4: 0x0000000107dff2b8
> liblldb.3.6.0.dylib`lldb_private::File::GetDescriptor(this=0x00007fe9b94420d8)
> const + 88 at File.cpp:146
> 	frame #5: 0x0000000107ec557c
> liblldb.3.6.0.dylib`lldb_private::IOHandler::GetInputFD(this=0x00007fe9b965f
> 4d0) + 92 at IOHandler.cpp:85
> 	frame #6: 0x00000001082831b8
> liblldb.3.6.0.dylib`IOHandlerProcessSTDIO(this=0x00007fe9b965f4d0,
> process=0x00007fe9ba031800, write_fd=5) + 184 at Process.cpp:4910
> 	frame #7: 0x00000001082797c3
> liblldb.3.6.0.dylib`IOHandlerProcessSTDIO(this=0x00007fe9b965f4d0,
> process=0x00007fe9ba031800, write_fd=5) + 35 at Process.cpp:4911
> 	frame #8: 0x000000010826df42
> liblldb.3.6.0.dylib`lldb_private::Process::SetSTDIOFileDescriptor(this=0x00007f
> e9ba031800, fd=5) + 642 at Process.cpp:5100
> 	frame #9: 0x000000010824fd8e
> liblldb.3.6.0.dylib`lldb_private::Platform::DebugProcess(this=0x00007fe9b952
> 8c10, launch_info=0x00007fff598962a8, debugger=0x00007fe9b9870c00,
> target=0x00007fe9b9880000, error=0x00007fff59896270) + 1406 at
> Platform.cpp:1138
> 	frame #10: 0x00000001085349f4
> liblldb.3.6.0.dylib`PlatformPOSIX::DebugProcess(this=0x00007fe9b9528c10,
> launch_info=0x00007fff598962a8, debugger=0x00007fe9b9870c00,
> target=0x00007fe9b9880000, error=0x00007fff59896270) + 244 at
> PlatformPOSIX.cpp:875
> 	frame #11: 0x00000001082cfde8
> liblldb.3.6.0.dylib`lldb_private::Target::Launch(this=0x00007fe9b9880000,
> launch_info=0x00007fff598962a8, stream=0x0000000000000000) + 1944 at
> Target.cpp:2462
> 	frame #12: 0x0000000108672c58
> liblldb.3.6.0.dylib`lldb::SBTarget::Launch(this=0x0000000106469178,
> listener=0x0000000106469400, argv=0x0000000000000000,
> envp=0x0000000000000000, stdin_path=0x0000000000000000,
> stdout_path=0x0000000000000000, stderr_path=0x0000000000000000,
> working_directory=0x0000000000000000, launch_flags=2,
> stop_at_entry=false, error=0x00007fff59896838) + 2088 at SBTarget.cpp:779
> 	frame #13: 0x00000001063aabea lldb-
> mi`CMICmdCmdExecRun::Execute(this=0x00007fe9ba851200) + 234 at
> MICmdCmdExec.cpp:94
> 	frame #14: 0x00000001063ab3cc lldb-mi`non-virtual thunk to
> CMICmdCmdExecRun::Execute(this=0x00007fe9ba851240) + 28 at
> MICmdCmdExec.cpp:113
> 	frame #15: 0x00000001063e5230 lldb-
> mi`CMICmdInvoker::CmdExecute(this=0x00000001064688e0,
> vCmd=0x00007fe9ba851200) + 272 at MICmdInvoker.cpp:216
> 	frame #16: 0x00000001063ea1b4 lldb-
> mi`CMICmdMgr::CmdExecute(this=0x00000001064698a0,
> vCmdData=0x00007fff598976b8) + 804 at MICmdMgr.cpp:211
> 	frame #17: 0x0000000106434ea6 lldb-
> mi`CMIDriver::ExecuteCommand(this=0x0000000106468bc0,
> vCmdData=0x00007fff598976b8) + 38 at MIDriver.cpp:1057
> 	frame #18: 0x0000000106433e23 lldb-
> mi`CMIDriver::InterpretCommandThisDriver(this=0x0000000106468bc0,
> vTextLine=0x00007fff59897d68, vwbCmdYesValid=0x00007fff59897cff) + 195
> at MIDriver.cpp:1009
> 	frame #19: 0x0000000106433477 lldb-
> mi`CMIDriver::InterpretCommand(this=0x0000000106468bc0,
> vTextLine=0x00007fff59897d68) + 55 at MIDriver.cpp:973
> 	frame #20: 0x00000001064332eb lldb-
> mi`CMIDriver::ReadStdinLineQueue(this=0x0000000106468bc0) + 651 at
> MIDriver.cpp:690
> 	frame #21: 0x0000000106432f9f lldb-
> mi`CMIDriver::DoMainLoop(this=0x0000000106468bc0) + 447 at
> MIDriver.cpp:630
> 	frame #22: 0x000000010643342c lldb-mi`non-virtual thunk to
> CMIDriver::DoMainLoop(this=0x0000000106468c00) + 28 at MIDriver.cpp:647
> 	frame #23: 0x0000000106442722 lldb-
> mi`CMIDriverMgr::DriverMainLoop(this=0x0000000106469500) + 66 at
> MIDriverMgr.cpp:344
> 	frame #24: 0x0000000106440311 lldb-mi`main(argc=2,
> argv=0x00007fff59898308) + 321 at MIDriverMain.cpp:352
> 	frame #25: 0x00007fff8b32a5fd libdyld.dylib`start + 1
> 	frame #26: 0x00007fff8b32a5fd libdyld.dylib`start + 1
>     (lldb)
> 
> 
> 
> I've offered to make the patch OSX-specific if that is preferred?
> 
> Thanks,
> -Dawn