persist_backend and Apache config

Bill Moseley moseley at
Tue Apr 1 14:22:18 UTC 2008

Two questions about persist_backend.

First, the mod_perl docs and the standard advice is to *not* use
keep-alives on the backend server.  Yet, I've see that persist_backend
is recommended.

Frankly, it would seem reasonable to maintain the connections,
although the overhead to setup a socket on a fast local LAN segment
is probably insignificant to the total request time.

Can someone explain this difference between the mod_proxy/mod_perl
recommendation and the perlbal recommendation?

(Actually, I thought the non-keep-alive recommendation for backend
Apache had something to do with lingerd).

Second, if persist_backen is recommended, what is the recommended
keep-alive settings for the Apache backend?

Oh, and one question about keep-alive on the client side.

The mod_perl sever in this case is only handling page content (no
static js, css, images, etc.).  So, a single page request from a
browser only generates one request to Perlbal reverse proxy.

Should keep-alive still be enabled on the client side?

The only time a normal user might make more than one request (in a
short amount of time) is if their browser does pre-caching, for
example, or they are very fast at reloading or following links.

Bill Moseley
moseley at

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