Merge branch 'issue-363' into master

3 files changed, 14 insertions, 0 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 96cf062..1caba39 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -51,6 +51,9 @@ Bug fixes:
 
 * Do not skip physical checks if the newline is escaped. (Issue #319)
 
+* Flush sys.stdout to avoid race conditions with printing. See flake8 bug:
+  https://gitlab.com/pycqa/flake8/issues/17 for more details. (Issue #363)
+
 
 1.5.7 (2014-05-29)
 ------------------
diff --git a/pep8.py b/pep8.py
index df39802..79497e2 100755
--- a/pep8.py
+++ b/pep8.py
@@ -1704,6 +1704,14 @@ class StandardReport(BaseReport):
                 print(re.sub(r'\S', ' ', line[:offset]) + '^')
             if self._show_pep8 and doc:
                 print('    ' + doc.strip())
+
+            # stdout is block buffered when not stdout.isatty().
+            # line can be broken where buffer boundary since other processes
+            # write to same file.
+            # flush() after print() to avoid buffer boundary.
+            # Typical buffer size is 8192. line written safely when
+            # len(line) < 8192.
+            sys.stdout.flush()
         return self.file_errors
 
 
diff --git a/testsuite/support.py b/testsuite/support.py
index 5185005..6bc795d 100644
--- a/testsuite/support.py
+++ b/testsuite/support.py
@@ -16,6 +16,9 @@ class PseudoFile(list):
     def getvalue(self):
         return ''.join(self)
 
+    def flush(self):
+        pass
+
 
 class TestReport(StandardReport):
     """Collect the results for the tests."""