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RE: Massive HTTP/2 parallel requests

From: Lucas Pardue <>
Date: Wed, 2 Mar 2016 16:10:14 +0000

> Does setting H2MaxWorkers on the Apache side help? Also note, that the
> Apache module is still experimental and in rapid development. Stefan
> publishes in trunk but also in The github
> one is more recent and gets reintegrated into Apache every now and then.
> So if you suspect a bug in the module, please also try the github variant.
> The github version has the following info in the entries for version 1.1.0:
> * H2SessionExtraFiles are now shared between all sessions in the same
> process.
> It now works like this:
> H2MaxWorkers * H2SessionFiles is assumed to be the total number of file
> handles that can be safely used for HTTP/2 transfers without other parts
> of the server running out of handles. This number is shared between all
> HTTP/2 connections in the same server process.
> The default is set to 2. With H2MaxWorkers on most platforms/mpms
> defaulting to 25 that gives a maximum of 50 handles that can be invoved in
> transfers.
> I think I have to write a blog post one day of how this works and affects
> performance. tl;dr the more handles http2 may use, the faster static files
> can be served.
> See also "H2SessionExtraFiles " on
> For questions on mod_http2 you might reach out to the httpd dev list.
> Stefan is quite responsive to questions about mod_http2.
> One might wonder though, which use case you want to support. Serving
> 1000 concurrent requests in a single connection creates a conflict between
> fairness - answering all requests at the same pace - and efficiency -
> answering them using the smallest amount of resources.
> Regards,
> Rainer

I agree with Rainer, if you can replicate the 64-limit in h2load it sounds like more of an issue with server/config rather than libcurl.


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Received on 2016-03-02