其他解决方案引用了大量的外部代码库。如果您更愿意自己动手，这里有一些跨平台解决方案的代码，在Linux / DOS系统上使用各自的文件锁定工具。

try:
    # Posix based file locking (Linux, Ubuntu, MacOS, etc.)
    #   Only allows locking on writable files, might cause
    #   strange results for reading.
    import fcntl, os
    def lock_file(f):
        if f.writable(): fcntl.lockf(f, fcntl.LOCK_EX)
    def unlock_file(f):
        if f.writable(): fcntl.lockf(f, fcntl.LOCK_UN)
except ModuleNotFoundError:
    # Windows file locking
    import msvcrt, os
    def file_size(f):
        return os.path.getsize( os.path.realpath(f.name) )
    def lock_file(f):
        msvcrt.locking(f.fileno(), msvcrt.LK_RLCK, file_size(f))
    def unlock_file(f):
        msvcrt.locking(f.fileno(), msvcrt.LK_UNLCK, file_size(f))


# Class for ensuring that all file operations are atomic, treat
# initialization like a standard call to 'open' that happens to be atomic.
# This file opener *must* be used in a "with" block.
class AtomicOpen:
    # Open the file with arguments provided by user. Then acquire
    # a lock on that file object (WARNING: Advisory locking).
    def __init__(self, path, *args, **kwargs):
        # Open the file and acquire a lock on the file before operating
        self.file = open(path,*args, **kwargs)
        # Lock the opened file
        lock_file(self.file)

    # Return the opened file object (knowing a lock has been obtained).
    def __enter__(self, *args, **kwargs): return self.file

    # Unlock the file and close the file object.
    def __exit__(self, exc_type=None, exc_value=None, traceback=None):        
        # Flush to make sure all buffered contents are written to file.
        self.file.flush()
        os.fsync(self.file.fileno())
        # Release the lock on the file.
        unlock_file(self.file)
        self.file.close()
        # Handle exceptions that may have come up during execution, by
        # default any exceptions are raised to the user.
        if (exc_type != None): return False
        else:                  return True        

现在，AtomicOpen可以在with块中使用，而在这里通常使用open语句。

警告:

如果在Windows上运行并且Python在调用exit之前崩溃，我不确定锁的行为是什么。 这里提供的锁定是建议的，而不是绝对的。所有潜在的竞争进程必须使用“AtomicOpen”类。 截至2020年11月9日，此代码仅锁定Posix系统上的可写文件。在发布之后的某一时刻，在此日期之前，使用fcntl是非法的。锁定只读文件。

我从grizzed -python中找到了一个简单而有效的(!)实现。

简单使用os.open(…， O_EXCL) + os.close()在windows上不起作用。

场景是这样的: 用户请求一个文件执行某些操作。然后，如果用户再次发送相同的请求，它会通知用户在第一个请求完成之前不会完成第二个请求。这就是为什么我使用锁定机制来处理这个问题。

下面是我的工作代码:

from lockfile import LockFile
lock = LockFile(lock_file_path)
status = ""
if not lock.is_locked():
    lock.acquire()
    status = lock.path + ' is locked.'
    print status
else:
    status = lock.path + " is already locked."
    print status

return status

好吧，所以我最终用我在这里写的代码，在我的网站上链接是死的，在archive.org上查看(也可在GitHub上)。我可以以以下方式使用它:

from filelock import FileLock

with FileLock("myfile.txt"):
    # work with the file as it is now locked
    print("Lock acquired.")

下面是一个如何使用filelock库的例子，它类似于Evan Fossmark的实现:

from filelock import FileLock

lockfile = r"c:\scr.txt"
lock = FileLock(lockfile + ".lock")
with lock:
    file = open(path, "w")
    file.write("123")
    file.close()

with lock:块中的任何代码都是线程安全的，这意味着它将在另一个进程访问该文件之前完成。

我更喜欢lockfile——平台独立的文件锁定