[Lldb-commits] [PATCH] D12558: Fix rare failure in TestProcessIO

Pavel Labath via lldb-commits lldb-commits at lists.llvm.org
Wed Sep 2 09:20:06 PDT 2015

labath created this revision.
labath added reviewers: clayborg, ovyalov.
labath added a subscriber: lldb-commits.

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.



Index: source/Target/Process.cpp
--- source/Target/Process.cpp
+++ source/Target/Process.cpp
@@ -1479,12 +1479,7 @@
-    // 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 @@
         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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