Jim Jagielski wrote:
On Oct 2, 2007, at 5:56 PM, Ruediger Pluem wrote:
Slightly off topic, but this gives me the idea that we could use
OPTIONS * as some kind of ping / health check for pooled connections
in mod_proxy_http before sending a request (at least in the reverse
proxy case before sending a request that is not idempotent or after
the connection has not been used for a certain amount of time).
The current is_connected check has a race condition if the keepalive
timer of the backend server kills the connection just after our check
and before it received our request.
:)
We already do similar with AJP where, right after
ap_proxy_connect_backend()
it does a quick check. I think we even discussed having HTTP do something
similar awhile ago...
It would be nice to have the health check running asynchronously from
the normal request handling (error detection for idle connections,
before requests fail). Even more important, the recovery test could be
done independently from request handling.
For this one would need some scheduling service (independent threads,
API extension for callbacks). A simple start could be something like the
monitor() hook. Although that one depends on the type of MPM and the
module scheduling service should not be decoupled from the timing of
important internal procedures.
Regards,
Rainer
