FileLock
Related Docs:
object FileLock
| package utils
Lock File path
Filesystem Handler
Try to perform an operation while holding a lock exclusively
Try to perform an operation while holding a lock exclusively
number of milliseconds during which the calling process will try to get the lock before it times out. -1 means no timeout
the result of the operation (if successful) when locked is acquired
TimeoutException if the lock could not be acquired within timeoutInMillis, or any exception thrown by op
if the lock was acquired but the operation failed
the lock is guaranteed freed upon normal or exceptional exit from this function.
Release the lock and delete the lock file.
Try to perform an operation while holding a lock exclusively
Try to perform an operation while holding a lock exclusively
number of milliseconds during which the calling process will try to get the lock before it time out. -1 means no timeout
the result of the operation (if successful) when locked is acquired, Failure otherwise the lock is guaranteed freed upon normal or exceptional exit from this function.
Try to gain the lock during timeoutInMillis millis
Try to gain the lock during timeoutInMillis millis
number of milliseconds during which the calling process will try to get the lock before it time out. -1 means no timeout
true when locked is acquired (caller is responsible for calling release(), false otherwise
HDFS does not have a file locking mechanism. We implement it here in the following way - A file is locked when it's modification time is less than 5000ms tahn the current time - If the modification time is older tahn the current time of more than 5000ms, it is considered unlocked. - The owner of a lock spawn a thread that update the modification every 5s to keep the lock - The process willing to get the lock check every 5s second for the modification time of the file to gain the lock. - When a process gain the lock, it deletes the file first and tries to create a new one, this make sure that of two process gaining the lock, only one will be able to recreate it after deletion.
To gain the lock, call tryLock(), to release it, call release(). If you are going to use the lock and release it within the same call stack frame, please consider calling tryExclusively() (as in
exclusive(delay) { action }) instead.