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https://issues.apache.org/jira/browse/TS-880?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Leif Hedstrom updated TS-880:
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Fix Version/s: (was: 3.1.1)
3.1.0
> Major performance problem with second request on same keep-alive connection
> ---------------------------------------------------------------------------
>
> Key: TS-880
> URL: https://issues.apache.org/jira/browse/TS-880
> Project: Traffic Server
> Issue Type: Bug
> Components: HTTP
> Affects Versions: 3.0.0, 2.1.4
> Environment: 32-bit TS on linux, using epoll. With
> proxy.config.http.keep_alive_enabled_out = 1
> Reporter: William Bardwell
> Assignee: William Bardwell
> Fix For: 3.1.0
>
> Attachments: performance.try3.diff, performance_2nd_req.diff,
> performance_2nd_req_another_version.patch, performance_2nd_req_try2.diff
>
>
> If I load the same URL through TS twice in a row to a server with keep-alives
> turned on I get really slow performance on the second request.
> E.g. (loading 212M over loopback with uncachable content, but results are
> similar with cachable content):
> % Total % Received % Xferd Average Speed Time Time Time
> Current
> Dload Upload Total Spent Left Speed
> 100 212M 100 212M 0 0 140M 0 0:00:01 0:00:01 --:--:--
> 142M*
> % Total % Received % Xferd Average Speed Time Time Time
> Current
> Dload Upload Total Spent Left Speed
> 100 212M 100 212M 0 0 6397k 0 0:00:34 0:00:34 --:--:--
> 6400k*
> If I turn off proxy.config.http.keep_alive_enabled_out the problem goes away,
> it can also be partially solved by making proxy.config.io.max_buffer_size
> really big (but it needs to be bigger for larger content, and that supports
> the comment below, and proves that it isn't the origin server's fault.)
> When I turn on debug messages it looks like the IO loop for the second
> request only wakes up every 10ms (when an epoll_wait times out) and then it
> reads and writes, for the first request it goes much faster without those
> pauses. My theory is that the issue is related to the the fact that the
> outgoing connection fd gets added to the epoll fd for the thread handling the
> first request and the first user agent fd is added to the same epoll fd, and
> it stays on that epoll fd. But the new user agent request is on a different
> epoll fd which I assume means is tied to a different thread.
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