Tech Note 2
InterProcessMutex acquire() can be used to return immediately if lock can't be acquired.
Details
It's not obvious from the docs, but calling InterProcessMutex.acquire(0, unit) will return immediately (i.e. without any waiting) if the lock cannot be acquired.
e.g.
InterProcessMutex lock = ...
boolean didLock = lock.acquire(0, TimeUnit.any);
if ( !didLock )
{
// comes back immediately
}