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https://issues.apache.org/jira/browse/HBASE-6778?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Lawlor updated HBASE-6778:
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Attachment: HBASE_6778_WIP_v1.patch
Work In Progress Update:
I have been working on implementing the outlined solution and have attached a
patch representing my progress thus far.
As it stands, the TestChoreService class is very rough and represents tests
that I wrote to simply test a few underlying concepts. More extensive and
robust test coverage will be implemented.
The two main classes that I have been developing are ScheduledChore.java and
ChoreService.java:
Progress/Details with respect to ScheduledChore.java:
- The ScheduledChore.java was designed with the current Chore implementation in
mind. I wanted to maintain all of the existing functionality while making it
compatible with the new workflow.
- A new concept that appears in ScheduledChore that is not present in the
existing Chore implementation is the concept of "missing start time".
ScheduledChores track the time between successive runs. If the time between
successive runs exceeds 1.5 * period then we say that the chore has missed its
start time and we notify the ChoreService of this event. This is a useful
workflow as it helps the ChoreService decide when it needs to increase the
number of threads.
Progress/Details with respect to ChoreService.java:
- The ChoreService.java class is the class that defines how Chores are
scheduled and how the thread count is controlled.
- The service allows Chores to be scheduled, cancelled, rescheduled, and
triggered immediately. It also provides some useful methods for checking the
status of scheduled chores.
- When chores are added and removed the ChoreService may make some decisions
with respect to the size of the core pool. For example, if a Chore that caused
an increase in the core pool size is removed from the service, an attempt is
made to reduce the core pool size.
The finer grain details can be seen by going through the patch attached above.
The next steps are to refine the test coverage and begin converting existing
Chores into ScheduledChores.
One design detail that I was hoping to get feedback on was where the instance
of ChoreService should live in the codebase. Is there an object that would be
suitable to hold an instance of ChoreService that could then be used to service
objects that want to start a periodic chore?
All feedback is greatly appreciated.
Thanks,
Jonathan
> Deprecate Chore; its a thread per task when we should have one thread to do
> all tasks
> -------------------------------------------------------------------------------------
>
> Key: HBASE-6778
> URL: https://issues.apache.org/jira/browse/HBASE-6778
> Project: HBase
> Issue Type: Bug
> Reporter: stack
> Assignee: Jonathan Lawlor
> Attachments: HBASE_6778_WIP_v1.patch, thread_dump_HMaster.local.out
>
>
> Should use something like ScheduledThreadPoolExecutor instead (Elliott said
> this first I think; J-D said something similar just now).
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