[Lldb-commits] [lldb] r246753 - Fix rare failure in TestProcessIO

Pavel Labath via lldb-commits lldb-commits at lists.llvm.org
Thu Sep 3 02:30:17 PDT 2015

Author: labath
Date: Thu Sep  3 04:30:17 2015
New Revision: 246753

URL: http://llvm.org/viewvc/llvm-project?rev=246753&view=rev
Fix rare failure in TestProcessIO

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


Modified: lldb/trunk/source/Target/Process.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Target/Process.cpp?rev=246753&r1=246752&r2=246753&view=diff
--- lldb/trunk/source/Target/Process.cpp (original)
+++ lldb/trunk/source/Target/Process.cpp Thu Sep  3 04:30:17 2015
@@ -1479,12 +1479,7 @@ Process::SetExitStatus (int status, cons
-    // 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)
@@ -4159,6 +4154,10 @@ Process::ShouldBroadcastEvent (Event *ev
         case eStateExited:
         case eStateUnloaded:
+            m_stdio_communication.Disconnect();
+            m_stdio_communication.StopReadThread();
+            m_stdin_forward = false;
             // fall-through
         case eStateConnected:
         case eStateAttaching:

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