Fix ProcessIO test failures

Summary:
There was a race condition regarding the output of the inferior process. The reading of the
output is performed on a separate thread, and there was no guarantee that the output will get
eventually consumed. Because of that, it was happening that calling Process::GetSTDOUT was not
returning anything even though the process was terminated and would definitely not produce any
further output. This was usually happening only under very heavy system load, but it can be
reproduced by placing an usleep in the stdio thread (Process::STDIOReadThreadBytesReceived).

This patch addresses this by adding synchronization capabilities to the Communication thread.
After calling Communication::SynchronizeWithReadThread one can be sure that all pending input has
been processed by the read thread. This function is then called after every public event which
stops the process to obtain the entire process output.

Test Plan: TestProcessIO.py should now succeed every time instead of flaking in and out.

Reviewers: clayborg, jingham

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D8246

llvm-svn: 232023

1 files changed, 0 insertions, 4 deletions

diff --git a/lldb/test/python_api/process/io/TestProcessIO.py b/lldb/test/python_api/process/io/TestProcessIO.py
index 2eb7c298a78..8181a94cfc2 100644
--- a/lldb/test/python_api/process/io/TestProcessIO.py
+++ b/lldb/test/python_api/process/io/TestProcessIO.py
@@ -21,7 +21,6 @@ class ProcessIOTestCase(TestBase):
     @unittest2.skipIf(sys.platform.startswith("win32"), "stdio manipulation unsupported on Windows")
     @python_api_test
     @dwarf_test
-    @expectedFailureLinux # this test fails 7/100 dosep runs
     def test_stdin_by_api_with_dwarf(self):
         """Exercise SBProcess.PutSTDIN()."""
         self.buildDwarf()
@@ -38,7 +37,6 @@ class ProcessIOTestCase(TestBase):
     @unittest2.skipIf(sys.platform.startswith("win32"), "stdio manipulation unsupported on Windows")
     @python_api_test
     @dwarf_test
-    @expectedFailureLinux # this test fails 4/100 dosep runs
     def test_stdin_redirection_with_dwarf(self):
         """Exercise SBLaunchInfo::AddOpenFileAction() for STDIN without specifying STDOUT or STDERR."""
         self.buildDwarf()
@@ -55,7 +53,6 @@ class ProcessIOTestCase(TestBase):
     @unittest2.skipIf(sys.platform.startswith("win32"), "stdio manipulation unsupported on Windows")
     @python_api_test
     @dwarf_test
-    @expectedFailureLinux # this test fails 2/100 dosep runs
     def test_stdout_redirection_with_dwarf(self):
         """Exercise SBLaunchInfo::AddOpenFileAction() for STDOUT without specifying STDIN or STDERR."""
         self.buildDwarf()
@@ -72,7 +69,6 @@ class ProcessIOTestCase(TestBase):
     @unittest2.skipIf(sys.platform.startswith("win32"), "stdio manipulation unsupported on Windows")
     @python_api_test
     @dwarf_test
-    @expectedFailureLinux # this test fails 5/100 dosep runs
     def test_stderr_redirection_with_dwarf(self):
         """Exercise SBLaunchInfo::AddOpenFileAction() for STDERR without specifying STDIN or STDOUT."""
         self.buildDwarf()