Only allow on thread to run when calling libBacktraceRecording.
Make sure the timeout is set to 0.5s for these.
<rdar://problem/16719510> 

llvm-svn: 207163
diff --git a/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetThreadItemInfoHandler.cpp b/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetThreadItemInfoHandler.cpp
index 47c883e..2114af6 100644
--- a/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetThreadItemInfoHandler.cpp
+++ b/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetThreadItemInfoHandler.cpp
@@ -355,6 +355,8 @@
     options.SetUnwindOnError (true);
     options.SetIgnoreBreakpoints (true);
     options.SetStopOthers (true);
+    options.SetTimeoutUsec(500000);
+    options.SetTryAllThreads (false);
     thread.CalculateExecutionContext (exe_ctx);
 
     if (m_get_thread_item_info_function == NULL)