Is a Java FileLock a POSIX advisory (fcntl) lock

Question

I have a C++ program that locks files using POSIX advisory locks. That is, it uses the POSIX fcntl system call for lock operations. I want a Java program to interoperate wit

Answer 1

Try this:

(1) Write a small java program that locks a file and sleeps (or otherwise stops executing).

(2) cat /proc/locks

(3) You'll see lines like the following:

24: POSIX  ADVISORY  READ  1784 08:01:27384070 1073742826 1073742335
25: FLOCK  ADVISORY  WRITE 815  00:0f:9772     0          EOF

Identify your process ID from column 5. If column 2 is FLOCK then flock is being used. If it is POSIX then column 2 will be POSIX, indicating fcntl (or lockf which is build on top of fcntl) is being used.

If java has to choose one or the other then POSIX would be the sensible choice as it supports record locking.