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https://issues.apache.org/jira/browse/MESOS-4740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15191486#comment-15191486
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Benjamin Mahler commented on MESOS-4740:
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If you can't reproduce the slowness, then it seems more likely that the metrics
computation isn't inherently slow, no? The implication of it being slow only
sometimes seems to be that sometimes the master and/or allocator are backlogged.
"Complete waste of CPU cycles" has an assumption that the only thing we care
about is how many CPU cycles are needed to accomplish our work. We care about
much more than just that, for example, how simple and understandable is the
code? By introducing event-driven counters, we'll be making the code more
complicated. If we want to make such a tradeoff, we first have to establish a
basis for it (there are endless places where we could reduce cpu cycles) and
measure what we're improving (how large is the improvement). I'm not saying we
shouldn't do it, but please first do a deeper analysis here and use benchmarks
to demonstrate that the improvement is worth it. For example,
https://reviews.apache.org/r/44675/ seems misdirected, I would be very
surprised if this has a non-negligible impact on what you're seeing.
> Improve master metrics/snapshot performace
> ------------------------------------------
>
> Key: MESOS-4740
> URL: https://issues.apache.org/jira/browse/MESOS-4740
> Project: Mesos
> Issue Type: Task
> Reporter: Cong Wang
> Assignee: Cong Wang
>
> [~drobinson] noticed retrieving metrics/snapshot statistics could be very
> inefficient.
> {noformat}
> [user@server ~]$ time curl -s localhost:5050/metrics/snapshot
> real 0m35.654s
> user 0m0.019s
> sys 0m0.011s
> {noformat}
> MESOS-1287 introduces a timeout parameter for this query, but for
> metric-collectors like ours they are not aware of such URL-specific
> parameter, so we need:
> 1) We should always have a timeout and set some default value to it
> 2) Investigate why master metrics/snapshot could take such a long time to
> complete under load.
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