スクリプト本体をファイルロックして多重起動抑止するタイムアウト付きサンプル。

sample.py

import sys
import time
import signal, errno
from contextlib import contextmanager
import fcntl

@contextmanager
def timeout(seconds):
    def timeout_handler(signum, frame):
        pass

    original_handler = signal.signal(signal.SIGALRM, timeout_handler)

    try:
        signal.alarm(seconds)
        yield
    finally:
        signal.alarm(0)
        signal.signal(signal.SIGALRM, original_handler)

with timeout(1):
    f = open("sample.py")
    try:
        fcntl.flock(f.fileno(), fcntl.LOCK_EX)
    except IOError as e:
        if e.errno != errno.EINTR:
            raise e
        print("Lock timed out")
        sys.exit(1)

time.sleep(10)