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        "author": "Joshua Tauberer",
        "author_email": "jt@occams.info",
        "bugtrack_url": null,
        "classifiers": [
            "Development Status :: 5 - Production/Stable",
            "Intended Audience :: Developers",
            "License :: CC0 1.0 Universal (CC0 1.0) Public Domain Dedication",
            "Programming Language :: Python :: 3",
            "Programming Language :: Python :: 3.4",
            "Programming Language :: Python :: 3.5",
            "Programming Language :: Python :: 3.6",
            "Topic :: Software Development :: Libraries :: Python Modules"
        ],
        "description": "exclusiveprocess - Simple Cross-Process Locking in Python\n=========================================================\n\nThis is a simple Python 3.4+ module for ensuring that your code does not\nexecute concurrently in multiple processes, using POSIX file locking.\n\nThe lock can be acquired easily using ``with`` syntax or as a decorator.\n\nWhy?\n----\n\nIf you have long-running processes that would cause corruption if it's\nexecuted multiple times concurrently, this package is for you. You might\nuse this in scripts that make backups, perform database migrations, or\nother long-running processes that need to abort if they are already\nrunning.\n\nHow it works under the hood\n---------------------------\n\nThe module uses POSIX file locking and a PID file:\n\n-  A file is selected to hold lock information, typically\n   ``/var/lock/py_exclusivelock_yournamehere.lock``, called the\n   lockfile, based on a name you provide. The name is sanitized before\n   being used in the filename.\n\n-  If the lockfile already exists and it contains the PID of a running\n   process (including the current process), then a ``CannotAcquireLock``\n   exception is thrown.\n\n-  Otherwise the lockfile is created (or overwritten) and this process's\n   integer process ID is written to the file. POSIX file locking (lockf)\n   and open with O_EXCL is used to prevent race conditions.\n\n-  The lockfile is deleted when the ``with`` block or decorated function\n   exits. Or when used with ``.forever()`` (see below), at program exit.\n\nHow to use it\n-------------\n\nFirst install this package:\n\n::\n\n    pip3 install exclusiveprocess\n\nThen in your Python file import the package:\n\n::\n\n    from exclusiveprocess import Lock, CannotAcquireLock\n\nYou can use it in a ``with`` statement:\n\n::\n\n    try:\n        with Lock(name=\"myprocess\"):\n            print(\"This block cannot be executed concurrently!\")\n    except CannotAcquireLock:\n        print(\"Well, that's bad.\")\n\nOr as a decorator:\n\n::\n\n    # lock name chosen based on __file__\n    @Lock\n    def myfunc():\n        print(\"This function cannot be executed concurrently!\")\n\n    # lock name is \"myprocess\"\n    @Lock(name=\"myprocess\")\n    def myfunc():\n        print(\"This function cannot be executed concurrently!\")\n\nThe ``name`` is up to you. The lock is specific to the name. The name is\nsystem global (as global as the file system is).\n\nThere are also some handy features for locking your whole program.\n\n1. The ``name`` argument is optional and defaults to the filename of the\n   module that contains the function that called ``Lock`` (i.e. your\n   Python source file), using\n   `inspect.stack() <https://docs.python.org/3.5/library/inspect.html#inspect.stack>`__,\n   which results in the Lock being automatically exclusive to all\n   invocations of your application.\n\n2. When you set the optional ``die`` keyword argument to ``True``,\n   ``Lock`` will print an error to STDERR and exit the process\n   immediately with exit code 1 if the lock cannot be acquired, instead\n   of rasing an exception.\n\n3. The lock can be acquired with ``.forever()``, instead of ``with`` or\n   decorator syntax, in which case the lock will be released only at\n   program exit using\n   `atexit <https://docs.python.org/3.5/library/atexit.html>`__.\n\nWith these features, you can make your whole program exclusive by\nplacing the following line at the start of your program:\n\n::\n\n    # At program start.\n    Lock(die=True).forever()\n    # program exits here if lock could not be acquired\n\nIf two such programs are run conncurrently you will see on STDERR:\n\n::\n\n    Another '/home/user/your_script.py' process is already running (pid 27922).\n\nAdvanced\n--------\n\nThe ``with`` object can be captured if you want to see where the\nlockfile is stored:\n\n::\n\n    with Lock(name=\"test1\") as lock:\n        print(lock.lockfile)\n\n    # outputs:\n    /var/lock/py_exclusivelock_test1.lock\n\nThe ``Lock`` class logs every lock acquired and released to\n``logging.info``.",
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        "home_page": "https://github.com/JoshData/exclusiveprocess",
        "keywords": "exclusive process POSIX lock pid concurrent global system",
        "license": "CC0 (copyright waived)",
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