Hello all:
I have apache2 setup with virtual domains. I am thinking about hosting some mod_perl pages in a number of domains.
I don't anticipate much traffic for now, so I can experiment with this stuff :)
Issue 1:
What strategies can I use to separate or isolate memory per virtual domain. I have read some of the documentation about reducing memory usage and increasing performance of apache mod_perl processes.
As a slight adaptation, I could have an apache server dedicated to each virdual domain waiting on some high port number. And configure a lightweight apache on port 80 (serving lightweight stuff for all domain) to redirect (using mod_rewrite perhaps) domain specific domain mod_perl calls to those high port numbers? This scheme certainly would make it easy to add extra machines when needed. However the configuration of my lightweight apache seems daunting. I would make sure that those high port numbers are firewalled so only my lightweight machine can see those ports...
Issue 2:
The various apache processes seem to each maintain a copy of domain specific data. For now I have an "application" variable that's used to keep everything in sync. During each request I tie the application session and check if a "mod counter" has been incremented, if so I reread the application data else I use the local copy. The data is mostly readonly and dependent on internal conditions.
One strategy that I have though of :
Use the startup handler (called during startup before the child processes are spawned right?) to calculate what the "application data" should be and intialize the tied "mod counter" hoping that it will never change :(. I suppose when the machine goes into production, if changes should occur infrequently or upon modification of certain data then you simply restart the server and thus keep this readonly "application" stuff in a shared memory space.
Perhaps I may even open two types of "application data": the kind that is almost guarenteed to remain static, and everything else and use two sessions to keep it all in sync.
What other strategies may be employed to treat such data? Is there a way update data in shared memory without apache creating a local copy?
Any comments are welcome; thanks in advance.
Leo
