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From Harrie Hazewinkel <>
Subject Re: Upgrade of the SNMP module for Apache 1.2.5
Date Thu, 22 Jan 1998 08:53:17 GMT
The reasons of this kind of SNMP-logging was that every process 
only has to do a small bit during the HTTP-request cycle and 
the SNMP-part during a SNMP-request has to do more. But this is 
justified by the fact that the number of SNMP-requests are much
less then the number of HTTP-requests. Another reason is that 
the SNMP-information is similar like the status-information; 
only 1 process may write in its own part and may read out of all parts.
The only thing is that when you have around 50 virtual hosts
the scorebaord becomes huge. 

Since I recently wanted to implement the complete WWW-MIB I ran 
into the problem that I need a sequence of the documents access
(sorted by virtual host). So I started to search for other ways
of maintaining the SNMP-information. I believe a UNIX-domain socket
is probably the best choice. Then all processes write a small 
datagram and send it to the UNIX-domain socket. The SNMP-process
has then to read all the packets and log the SNMP-information.
The only drawback here is that the processing cylces go up,
but we do not have the SNMP-information in shared memeory 
and in size multplied by the number of apache processes.

Dirk-Willem van Gulik wrote:
> On Tue, 20 Jan 1998, Ben Laurie wrote:
> > Dean Gaudet wrote:
> > > core.  (Yup it would be so nice if we would abstract shared memory so you
> > > don't have to do all the same crud we do.  A patch for that would be
> > > awesome.)
> > I keep thinking about this one - the problem is that we need something
> > more than just a shared memory abstraction, don't we? Unless you happen
> > to want to store something that's fixed length and one-per-process, that
> > is.
> I got as far as adding an extra struct to the module vector with allows
> for the registry of a 'shared_len(0 | pid) and shared_ptr(0 | pid)'
> function pointers.But unless you are a very displined programmer; it is
> easy to abuse that interface and end up with a per-process/per-vhost type
> of strorage which is sparsely used.
> Dw.

0- Harrie Hazewinkel --------------------------------------0       phone:+39+332+789384            fax:+39+332+785500
 postal: JRC of the E.C.  -  CEO unit
         Ispra 21020 (VA) Italy
  Ik ben Harrie en ik ben 28 jaar en doe SNMP na. MIB, MIB

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