Fix rare failure in TestProcessIO

Summary:
There was a race condition in Process class, where we would not wait for process stdout to
propagate fully before we would shut down the connection (repro case: slow down the stdio thread
by placing a sleep right at the end of the while loop in Communication::ReadThread). The Process
class already tried to solve this problem by synchronizing with the read thread in
Process::ShouldBroadcastEvent, but unfortunately the connection got closed before that in
Process::SetExitStatus. I solve this issue by delaying the connection shutdown until we get a
chance to process the event and synchronize. Alternatively, I could have moved the
synchronization point to an earlier point in SetExitStatus, but it seems safer to delay the
shutdown until other things get a chance to notice the process has exited.

Reviewers: clayborg, ovyalov

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D12558

llvm-svn: 246753

1 files changed, 5 insertions, 6 deletions

diff --git a/lldb/source/Target/Process.cpp b/lldb/source/Target/Process.cpp
index 531a14c00fa..c771be0bf9a 100644
--- a/lldb/source/Target/Process.cpp
+++ b/lldb/source/Target/Process.cpp
@@ -1479,12 +1479,7 @@ Process::SetExitStatus (int status, const char *cstr)
     else
         m_exit_string.clear();
 
-    // When we exit, we no longer need to the communication channel
-    m_stdio_communication.Disconnect();
-    m_stdio_communication.StopReadThread();
-    m_stdin_forward = false;
-
-    // And we don't need the input reader anymore as well
+    // When we exit, we don't need the input reader anymore
     if (m_process_input_reader)
     {
         m_process_input_reader->SetIsDone(true);
@@ -4159,6 +4154,10 @@ Process::ShouldBroadcastEvent (Event *event_ptr)
         case eStateExited:
         case eStateUnloaded:
             m_stdio_communication.SynchronizeWithReadThread();
+            m_stdio_communication.Disconnect();
+            m_stdio_communication.StopReadThread();
+            m_stdin_forward = false;
+
             // fall-through
         case eStateConnected:
         case eStateAttaching: