[Python-checkins] cpython (merge 3.2 -> default): Issue #14632: Updated WatchedFileHandler to deal with race condition. Thanks to
vinay.sajip
python-checkins at python.org
Wed Apr 25 00:33:46 CEST 2012
http://hg.python.org/cpython/rev/380821b47872
changeset: 76545:380821b47872
parent: 76541:08d4c2fe51ea
parent: 76544:5de7c3d64f2a
user: Vinay Sajip <vinay_sajip at yahoo.co.uk>
date: Tue Apr 24 23:33:33 2012 +0100
summary:
Issue #14632: Updated WatchedFileHandler to deal with race condition. Thanks to John Mulligan for the problem report and patch.
files:
Lib/logging/handlers.py | 49 +++++++++++++++++----------
Lib/test/test_logging.py | 45 ++++++++++++++++++++++--
2 files changed, 70 insertions(+), 24 deletions(-)
diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py
--- a/Lib/logging/handlers.py
+++ b/Lib/logging/handlers.py
@@ -23,7 +23,7 @@
To use, simply 'import logging.handlers' and log away!
"""
-import logging, socket, os, pickle, struct, time, re
+import errno, logging, socket, os, pickle, struct, time, re
from codecs import BOM_UTF8
from stat import ST_DEV, ST_INO, ST_MTIME
import queue
@@ -419,11 +419,13 @@
"""
def __init__(self, filename, mode='a', encoding=None, delay=False):
logging.FileHandler.__init__(self, filename, mode, encoding, delay)
- if not os.path.exists(self.baseFilename):
- self.dev, self.ino = -1, -1
- else:
- stat = os.stat(self.baseFilename)
- self.dev, self.ino = stat[ST_DEV], stat[ST_INO]
+ self.dev, self.ino = -1, -1
+ self._statstream()
+
+ def _statstream(self):
+ if self.stream:
+ sres = os.fstat(self.stream.fileno())
+ self.dev, self.ino = sres[ST_DEV], sres[ST_INO]
def emit(self, record):
"""
@@ -433,21 +435,30 @@
has, close the old stream and reopen the file to get the
current stream.
"""
- if not os.path.exists(self.baseFilename):
- stat = None
- changed = True
- else:
- stat = os.stat(self.baseFilename)
- changed = (stat[ST_DEV] != self.dev) or (stat[ST_INO] != self.ino)
- if changed and self.stream is not None:
- self.stream.flush()
- self.stream.close()
- self.stream = self._open()
- if stat is None:
- stat = os.stat(self.baseFilename)
- self.dev, self.ino = stat[ST_DEV], stat[ST_INO]
+ # Reduce the chance of race conditions by stat'ing by path only
+ # once and then fstat'ing our new fd if we opened a new log stream.
+ # See issue #14632: Thanks to John Mulligan for the problem report
+ # and patch.
+ try:
+ # stat the file by path, checking for existence
+ sres = os.stat(self.baseFilename)
+ except OSError as err:
+ if err.errno == errno.ENOENT:
+ sres = None
+ else:
+ raise
+ # compare file system stat with that of our stream file handle
+ if not sres or sres[ST_DEV] != self.dev or sres[ST_INO] != self.ino:
+ if self.stream is not None:
+ # we have an open file handle, clean it up
+ self.stream.flush()
+ self.stream.close()
+ # open a new file handle and get new stat info from that fd
+ self.stream = self._open()
+ self._statstream()
logging.FileHandler.emit(self, record)
+
class SocketHandler(logging.Handler):
"""
A handler class which writes logging records, in pickle format, to
diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -1,6 +1,6 @@
#!/usr/bin/env python
#
-# Copyright 2001-2011 by Vinay Sajip. All Rights Reserved.
+# Copyright 2001-2012 by Vinay Sajip. All Rights Reserved.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose and without fee is hereby granted,
@@ -18,7 +18,7 @@
"""Test harness for the logging module. Run all tests.
-Copyright (C) 2001-2011 Vinay Sajip. All Rights Reserved.
+Copyright (C) 2001-2012 Vinay Sajip. All Rights Reserved.
"""
import logging
@@ -33,6 +33,7 @@
import json
import os
import queue
+import random
import re
import select
import socket
@@ -539,8 +540,8 @@
h = logging.handlers.WatchedFileHandler(fn, delay=True)
if existing:
dev, ino = h.dev, h.ino
- self.assertNotEqual(dev, -1)
- self.assertNotEqual(ino, -1)
+ self.assertEqual(dev, -1)
+ self.assertEqual(ino, -1)
r = logging.makeLogRecord({'msg': 'Test'})
h.handle(r)
# Now remove the file.
@@ -581,6 +582,41 @@
self.assertFalse(h.shouldFlush(r))
h.close()
+ @unittest.skipUnless(threading, 'Threading required for this test.')
+ def test_race(self):
+ # Issue #14632 refers.
+ def remove_loop(fname, tries):
+ for _ in range(tries):
+ try:
+ os.unlink(fname)
+ except OSError:
+ pass
+ time.sleep(0.004 * random.randint(0, 4))
+
+ def cleanup(remover, fn, handler):
+ handler.close()
+ remover.join()
+ if os.path.exists(fn):
+ os.unlink(fn)
+
+ fd, fn = tempfile.mkstemp('.log', 'test_logging-3-')
+ os.close(fd)
+ del_count = 1000
+ log_count = 1000
+ remover = threading.Thread(target=remove_loop, args=(fn, del_count))
+ remover.daemon = True
+ remover.start()
+ for delay in (False, True):
+ h = logging.handlers.WatchedFileHandler(fn, delay=delay)
+ self.addCleanup(cleanup, remover, fn, h)
+ f = logging.Formatter('%(asctime)s: %(levelname)s: %(message)s')
+ h.setFormatter(f)
+ for _ in range(log_count):
+ time.sleep(0.005)
+ r = logging.makeLogRecord({'msg': 'testing' })
+ h.handle(r)
+
+
class BadStream(object):
def write(self, data):
raise RuntimeError('deliberate mistake')
@@ -3724,7 +3760,6 @@
# Failures occur on some systems for MIDNIGHT and W0.
# Print detailed calculation for MIDNIGHT so we can try to see
# what's going on
- import time
if when == 'MIDNIGHT':
try:
if rh.utc:
--
Repository URL: http://hg.python.org/cpython
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