Issue #12493: subprocess: communicate() handles EINTR

subprocess.Popen.communicate() now also handles EINTR errors if the process has
only one pipe.

Lib/subprocess.py

@@ -450,7 +450,7 @@ def _eintr_retry_call(func, *args):
     while True:
         try:
             return func(*args)
-        except OSError as e:
+        except (OSError, IOError) as e:
             if e.errno == errno.EINTR:
                 continue
             raise
@@ -804,10 +804,10 @@ class Popen(object):
                             raise
                 self.stdin.close()
             elif self.stdout:
-                stdout = self.stdout.read()
+                stdout = _eintr_retry_call(self.stdout.read)
                 self.stdout.close()
             elif self.stderr:
-                stderr = self.stderr.read()
+                stderr = _eintr_retry_call(self.stderr.read)
                 self.stderr.close()
             self.wait()
             return (stdout, stderr)

Lib/test/test_subprocess.py

@@ -675,6 +675,22 @@ class ProcessTestCase(BaseTestCase):
         time.sleep(2)
         p.communicate(b"x" * 2**20)
 
+    def test_communicate_eintr(self):
+        # Issue #12493: communicate() should handle EINTR
+        def handler(signum, frame):
+            pass
+        old_handler = signal.signal(signal.SIGALRM, handler)
+        self.addCleanup(signal.signal, signal.SIGALRM, old_handler)
+
+        # the process is running for 2 seconds
+        args = [sys.executable, "-c", 'import time; time.sleep(2)']
+        for stream in ('stdout', 'stderr'):
+            kw = {stream: subprocess.PIPE}
+            with subprocess.Popen(args, **kw) as process:
+                signal.alarm(1)
+                # communicate() will be interrupted by SIGALRM
+                process.communicate()
+
 
 # context manager
 class _SuppressCoreFiles(object):

Misc/NEWS

@@ -21,6 +21,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #12493: subprocess: Popen.communicate() now also handles EINTR errors
+  if the process has only one pipe.
+
 - Issue #12467: warnings: fix a race condition if a warning is emitted at
   shutdown, if globals()['__file__'] is None.