# HG changeset patch
# Parent ca54c27a9045c655ef1ad9ce248f02eb00137476
diff -r ca54c27a9045 -r 1776829d890f Lib/subprocess.py
--- a/Lib/subprocess.py	Tue Aug 21 14:54:22 2012 +0100
+++ b/Lib/subprocess.py	Tue Aug 21 22:47:06 2012 +0100
@@ -1152,8 +1152,18 @@
 
 
         def _readerthread(self, fh, buffer):
-            buffer.append(fh.read())
-            fh.close()
+            try:
+                L = []
+                while True:
+                    chunk = fh.read(4096)
+                    if not chunk:
+                        break
+                    L.append(chunk)
+            finally:
+                fh.close()
+            empty_string = type(chunk)()           # either '' or b''
+            result = empty_string.join(L)
+            buffer.append(result)
 
 
         def _communicate(self, input, endtime, orig_timeout):