A gotcha with fcntl file locking

Published 2015-09-26.

Today I ran into an issue with fcntl(2) file locking [1] on Linux. A little research confirmed my fear:

From On the Brokenness of File Locking:

The worst part however is that POSIX locks are automatically released if a process calls close() on any (!) of its open file descriptors for that file.

The whole post is well worth a read.

[1] Which is what OpenJDK uses for FileChannel#lock.

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Tags: *nix, Linux, JVM, programming, old blog.