On 19Apr2021 23:13, Peter J. Holzer <hjp-pyt...@hjp.at> wrote: >On 2021-04-19 08:54:06 +1000, Cameron Simpson wrote: >> My personal preference is lock directories. Shell version goes like >> this: >> >> if mkdir /my/lock/directory/name-of-task >> then >> .. do task .. >> rmdir /my/lock/directory/name-of-task >> else >> echo "lock /my/lock/directory/name-of-task already taken" >> fi >> >> Simple, reliable, even works over NFS if you care. > >Reliable only if "fail locked" is acceptable. If that process dies for >some reason the lock directory will stay behind, blocking other >processes until somebody notices the problem and removes it.
A Python context manager narrows the range of circumstances for this failure quite a lot. But yes. >The fcntl method suggested by several people has the advantage that the >lock vanished with the process which holds it. This is very true. OTOH, mkdir's easy to debug if it hangs around. Cheers, Cameron Simpson <c...@cskk.id.au> -- https://mail.python.org/mailman/listinfo/python-list
