Apache HTTPD MPM Worker or Event for Reverse Proxy with SSL Termination

Question

I'm running reverse proxies with httpd 2.4.27 on RHEL 6 for various organizational reasons. The reverse proxies have to terminate SSL/TLS instead of the load balancer, which makes me want to consider how mpm_event handles SSL connections.

I've read several places that mpm_event may fall back to mpm_worker when handling SSL connections. I cannot find a definitive answer if that's still the case in my version. Is that still how it works?

Do you have an example of where you read that? It sounds a little unbelievable. — Michael Hampton, Aug 10 '18 at 14:47
https://serverfault.com/questions/383526/how-do-i-select-which-apache-mpm-to-use — gator2003, Aug 13 '18 at 14:37

score 0 · Answer 1 · answered Aug 10 '18 at 15:18

Actually, mpm_event can fall back to synchronous reads similar to what mpm_worker does when input filters are clogged, not the mpm_worker module itself (MPM modules don't change at runtime). mod_ssl is mentioned as one possible source of this clogging of input filters.

I haven't experienced any issues due to this handling myself, so I can't comment whether this is a bad thing or not.

You can find the relevant code here in the Apache HTTPd source code repository.

Apache HTTPD MPM Worker or Event for Reverse Proxy with SSL Termination

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