$ time python hello.py # 64kreal0m25.999suser0m9.753ssys0m29.687sreal0m25.964suser0m9.553ssys0m29.854s$ time python hello.py # 256kreal0m25.927suser0m9.421ssys0m29.958sreal0m25.933suser0m9.330ssys0m30.108s

diff --git a/Lib/multiprocessing/connection.py b/Lib/multiprocessing/connection.pyindex ede5596e4fc..9c1bfb93728 100644--- a/Lib/multiprocessing/connection.py+++ b/Lib/multiprocessing/connection.py@@ -544,7 +544,10 @@ def Pipe(duplex=True):             c1 = Connection(s1.detach())             c2 = Connection(s2.detach())         else:+            import fcntl             fd1, fd2 = os.pipe()+            fcntl.fcntl(fd1, fcntl.F_SETPIPE_SZ, 256*1024)+            fcntl.fcntl(fd2, fcntl.F_SETPIPE_SZ, 256*1024)             c1 = Connection(fd1, writable=False)             c2 = Connection(fd2, readable=False)