Hello,

What version of libcurl are you using? There were some issues with libcurl's multiplexing reported in January that were fixed, see https://curl.haxx.se/mail/lib-2016-01/0031.html.

Note that the maximum number of concurrent streams is directional (https://http2.github.io/http2-spec/#SETTINGS_MAX_CONCURRENT_STREAMS). It sounds like perhaps the server is restricting you to only 64 concurrent client-initiated streams per connection. Can you tell us the value the server is using? If you don't have access to server config a packet trace of the SETTINGS frame (or dump in client code) will let us know.

Regards
Lucas

> -----Original Message-----
> From: curl-library [mailto:curl-library-bounces_at_cool.haxx.se] On Behalf Of
> Molina
> Sent: 02 March 2016 09:47
> To: curl-library_at_cool.haxx.se
> Subject: Massive HTTP/2 parallel requests
>
> Hello,
>
> I’m working in a project that downloads a decent amount of files
> simultaneously, with an average size of 512KB. We’ve been using CURL with
> HTTP/1.1 requests so far, and I’ve been modifying the code to adapt it to
> HTTP/2.0. However, when trying to simultaneously download 1024 files for
> testing I realised only 64 where actually active, while the rest were idle. I was
> using only one multiplexed connection with CURLOPT_PIPEWAIT enabled.
>
> Secondly, just in order to try I set the following flags:
>
> curl_multi_setopt(multi_handle, CURLMOPT_MAX_TOTAL_CONNECTIONS ,
> 1024);
> curl_multi_setopt(multi_handle, CURLMOPT_MAX_HOST_CONNECTIONS,
> 1024);
>
> Which apparently enabled multiple 64-file-wide HTTP/2.0 connections,
> where each one received the corresponding “101, switching protocols”
> answer.
> Is this limit something desirable or convenient for the performance of
> HTTP/2.0? Would you have an advice for this use case?
>
> Thanks a lot in advance, and best regards.
> José Molina

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Received on 2016-03-02