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worker: ability to disable thread unsafe tasks...
worker: ability to disable thread unsafe tasks The worker on Windows is implemented using a thread pool. If worker tasks are not thread safe, badness can occur. In addition, if tasks are executing CPU bound code and holding onto the GIL, there will be non-substantial overhead in Python context switching between active threads. This can result in significant slowdowns of tasks. This commit teaches the code for determining whether to use a worker to take thread safety into account. Effectively, thread unsafe tasks don't use the thread-based worker on Windows. Differential Revision: https://phab.mercurial-scm.org/D3962

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txnutil.py
36 lines | 1.0 KiB | text/x-python | PythonLexer
# txnutil.py - transaction related utilities
#
# Copyright FUJIWARA Katsunori <foozy@lares.dti.ne.jp> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import errno
from . import (
encoding,
)
def mayhavepending(root):
'''return whether 'root' may have pending changes, which are
visible to this process.
'''
return root == encoding.environ.get('HG_PENDING')
def trypending(root, vfs, filename, **kwargs):
'''Open file to be read according to HG_PENDING environment variable
This opens '.pending' of specified 'filename' only when HG_PENDING
is equal to 'root'.
This returns '(fp, is_pending_opened)' tuple.
'''
if mayhavepending(root):
try:
return (vfs('%s.pending' % filename, **kwargs), True)
except IOError as inst:
if inst.errno != errno.ENOENT:
raise
return (vfs(filename, **kwargs), False)