[libmicrohttpd] High CPU usage when using HTTPS and poll

[Lorenzo Miniero]

Hi,

I'm using MHD in an open source WebRTC gateway called Janus (https://github.com/meetecho/janus-gateway) and it works great. In particular, the web server is configured to open a new thread for each connection and to use poll (MHD_USE_THREAD_PER_CONNECTION | MHD_USE_POLL).

Whenever I involve HTTPS, though, I get high CPU usage after the first request even when no connection is being handled. Attaching to the process via gdb it looks like the cause is the poll method going crazy, which is weird considering that the same exact code in my application is shared between HTTP and HTTPS, and that this only happens for HTTPS requests.

I tried looking into the archives to see if there was anything related to that, but the only post I could find was a quite old one that has apparently been fixed in the meanwhile (http://lists.gnu.org/archive/html/libmicrohttpd/2010-02/msg00003.html).

What could be the cause of the issue? Is this a known issue, or is there anything I may be doing wrong when configuring the MHD_Daemon instance? Just FYI, I'm using the packaged libmicrohttpd provided by Fedora 18 (0.9.22, x86_64).

Thanks,

Lorenzo