Try to reduce the extreme peak memory and disk-space use

of this test.  It probably still requires more disk space
than most buildbots have, and in any case is still so
intrusive that if we don't find another way to test this I'm
taking my buildbot offline permanently ;-)

Lib/test/test_zipfile64.py

@@ -3,7 +3,7 @@
 # from test_zipfile
 from test import test_support
 test_support.requires(
-        'largefile', 
+        'largefile',
         'test requires loads of disk-space bytes and a long time to run'
     )
 
@@ -29,22 +29,28 @@ _PRINT_WORKING_MSG_INTERVAL = 5 * 60
 
 class TestsWithSourceFile(unittest.TestCase):
     def setUp(self):
-        line_gen = ("Test of zipfile line %d." % i for i in range(0, 1000000))
+        # Create test data.
+        # xrange() is important here -- don't want to create immortal space
+        # for a million ints.
+        line_gen = ("Test of zipfile line %d." % i for i in xrange(1000000))
         self.data = '\n'.join(line_gen)
 
-        # Make a source file with some lines
+        # And write it to a file.
         fp = open(TESTFN, "wb")
         fp.write(self.data)
         fp.close()
 
     def zipTest(self, f, compression):
-        # Create the ZIP archive
-        filecount = int(((1 << 32) / len(self.data)) * 1.5)
+        # Create the ZIP archive.
         zipfp = zipfile.ZipFile(f, "w", compression, allowZip64=True)
 
+        # It will contain enough copies of self.data to reach about 6GB of
+        # raw data to store.
+        filecount = 6*1024**2 // len(self.data)
+
         next_time = time.time() + _PRINT_WORKING_MSG_INTERVAL
         for num in range(filecount):
-            zipfp.writestr("testfn%d"%(num,), self.data)
+            zipfp.writestr("testfn%d" % num, self.data)
             # Print still working message since this test can be really slow
             if next_time <= time.time():
                 next_time = time.time() + _PRINT_WORKING_MSG_INTERVAL
@@ -57,7 +63,7 @@ class TestsWithSourceFile(unittest.TestCase):
         # Read the ZIP archive
         zipfp = zipfile.ZipFile(f, "r", compression)
         for num in range(filecount):
-            self.assertEqual(zipfp.read("testfn%d"%(num,)), self.data)
+            self.assertEqual(zipfp.read("testfn%d" % num), self.data)
             # Print still working message since this test can be really slow
             if next_time <= time.time():
                 next_time = time.time() + _PRINT_WORKING_MSG_INTERVAL
@@ -68,17 +74,22 @@ class TestsWithSourceFile(unittest.TestCase):
         zipfp.close()
 
     def testStored(self):
-        for f in (TESTFN2, TemporaryFile()):
+        # Try the temp file first.  If we do TESTFN2 first, then it hogs
+        # gigabytes of disk space for the duration of the test.
+        for f in TemporaryFile(), TESTFN2:
             self.zipTest(f, zipfile.ZIP_STORED)
 
     if zlib:
         def testDeflated(self):
-            for f in (TESTFN2, TemporaryFile()):
+            # Try the temp file first.  If we do TESTFN2 first, then it hogs
+            # gigabytes of disk space for the duration of the test.
+            for f in TemporaryFile(), TESTFN2:
                 self.zipTest(f, zipfile.ZIP_DEFLATED)
 
     def tearDown(self):
-        os.remove(TESTFN)
-        os.remove(TESTFN2)
+        for fname in TESTFN, TESTFN2:
+            if os.path.exists(fname):
+                os.remove(fname)
 
 def test_main():
     run_unittest(TestsWithSourceFile)