From 9c182a1e25409a241cf1f7e8d0141199dd4344c9 Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@gmail.com>
Date: Mon, 16 Mar 2015 18:03:06 +0100
Subject: [PATCH] Issue #23680: Reduce risk of race condition in
 check_interrupted_write() of test_io. Allocate the large data before
 scheduling an alarm in 1 second.

On very slow computer, the alarm rings sometimes during the memory allocation.
---
 Lib/test/test_io.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index abbd6611de1..e5c6073ba32 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -3431,6 +3431,7 @@ class SignalsTest(unittest.TestCase):
         t.daemon = True
         r, w = os.pipe()
         fdopen_kwargs["closefd"] = False
+        large_data = item * (support.PIPE_MAX_SIZE // len(item) + 1)
         try:
             wio = self.io.open(w, **fdopen_kwargs)
             t.start()
@@ -3442,8 +3443,7 @@ class SignalsTest(unittest.TestCase):
             # handlers, which in this case will invoke alarm_interrupt().
             signal.alarm(1)
             try:
-                self.assertRaises(ZeroDivisionError,
-                            wio.write, item * (support.PIPE_MAX_SIZE // len(item) + 1))
+                self.assertRaises(ZeroDivisionError, wio.write, large_data)
             finally:
                 signal.alarm(0)
             t.join()