Improve file lock contention handling This commit improves the likelihood for lock requesters to acquire a file lock after it is released due to contention. After the lock has been released, the former lock holder now sends a packet to the sockets of all requesters. While old clients will simply ignore the additional packet, new clients will interpret it as a signal that the file lock has been released and will try to acquire it immediately.
Restart timer if the lock owner changes If many processes fight and wait for the same lock, the timeout in one process could be triggered, because it is "last in line". All the times others hold the lock are added up for the timeout. This change resets the timeout as soon as the lock owner changes.