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https://issues.apache.org/jira/browse/TS-1405?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13611749#comment-13611749
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John Plevyak commented on TS-1405:
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I think depending on the delay is brittle. You can never tell how long a
thread will be delayed in an overloaded system, and the delay increases memory
pressure. Rather I would remove the delay, moving the line
+ event_cancel_list_head = (Event *) ink_atomiclist_popall(&event_cancel_list);
above the loop in process_cancel_event() (and remove the time test).
Then I would move the assignment of cancelled = true into set_event_cancel:
if (!e->canceled) {
if (e->in_the_priority_queue && (e->timeout_at - e->ethread->cur_time) >
HRTIME_SECONDS(event_cancel_limit)) {
/* prevent more threads cancel one event racing */
e->cancelled = true;
ink_atomiclist_push(&event_cancel_list, e);
} else
e->cancelled = true;
}
In fact, I would just incorporate the code in set_event_cancel into
cancel_event() since it is only called in one place.
So, I agree, that the delay would most likely have prevented a problem, but I
think it would be better to not have it, because when future programmers see a
constant delay, they might be tempted to decrease it to the point when problems
might occur.
> apply time-wheel scheduler about event system
> ----------------------------------------------
>
> Key: TS-1405
> URL: https://issues.apache.org/jira/browse/TS-1405
> Project: Traffic Server
> Issue Type: Improvement
> Components: Core
> Affects Versions: 3.2.0
> Reporter: Bin Chen
> Assignee: Bin Chen
> Fix For: 3.3.2
>
> Attachments: linux_time_wheel.patch, linux_time_wheel_v2.patch,
> linux_time_wheel_v3.patch, linux_time_wheel_v4.patch,
> linux_time_wheel_v5.patch, linux_time_wheel_v6.patch,
> linux_time_wheel_v7.patch, linux_time_wheel_v8.patch
>
>
> when have more and more event in event system scheduler, it's worse. This is
> the reason why we use inactivecop to handler keepalive. the new scheduler is
> time-wheel. It's have better time complexity(O(1))
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