Elias Torres wrote:
I like the proposal and I think it's very important/useful.
I would suggest though to not use a hard-coded expiration mechanism and
instead use a leasing mechanism. I propose that a task says it needs the
lock for X number of minutes/hours and writes the time it started and
the lease amount. It just a subtle tweak, but it optimizes the
scheduling a bit, so a quick task like saving referrers can get a 3-min
lease and not block 3 hours of thread time. Additionally, they could
store the name of the task, so parallel tasks can work w/o blocking each
other and only tasks with the same service name wait on each other.
Obviously, a task can extend their lease if needed to run for more time.
For example, let's store this as the
property: task.indexing value: 12:00:01,3mins
yep, I can do it that way. I guess I consider this to be the same thing
because the lease time for a given task is not likely to ever change, so
if the task knows what the lease time is for its lock then there is no
reason the lease needs to be in the db. Obviously if the lease time may
vary for a given lock then your approach makes a lot more sense.
Either way will work, but yours is slightly more flexible so I'll do it
that way. For the actual property I am going to simplify the value so
that it's just long<time>, long<lease>.
So if you see the lease in the db it would be
property: task.indexing value: 983472893, 1800
This way it's just easier for the application to use the values without
actually having to worry about parsing date strings.
Thanks for the suggestion.
-- Allen
In other words, let's re-invent JINI.
-Elias
Allen Gilliland wrote:
This is a really short one, but I did a proposal anyways. I'd like to
add a simple locking mechanism to the various background tasks that we
have so that running them in clustered environments is safe from
synchronization issues and we can prevent a task from running at the
same time on multiple machines in the cluster.
http://rollerweblogger.org/wiki/Wiki.jsp?page=Proposal_ClusteredTasksViaLocking
Since this is such a short proposal I'd like to go ahead and propose a
vote on the proposal as is, since I don't expect there is a need for
lots of discussion. This would go into Roller 3.1.
-- Allen
