pythonで多重起動禁止

fcntl --- fcntl および ioctl システムコール — Python 3.9.1 ドキュメント

lock_test.py

import os
import fcntl
import time

def process_lock():
    lockfile = os.path.splitext(os.path.abspath(__file__))[0] + '.lock'
    lockfp = open(lockfile, "w")
    try:
        fcntl.flock(lockfp, fcntl.LOCK_EX | fcntl.LOCK_NB)
    except IOError:
        return
    return lockfp

def main():
    lock = process_lock()
    if not lock:
        print("lock error")
        exit(1)

    # 処理
    time.sleep(360)

if __name__ == '__main__':
    main()

$ python3 lock_test.py &
$ python3 lock_test.py
lock error