Fastcgi and persistence in sub modules

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Dear monks,

In the context of web scripting, say I've a main fastcgi-enabled script that imports Module A (before the "while" loop). Module A in turn imports Module B and Module C.

Since Module A is loaded before the "while" loop in the main script, it's saved in memory. But what about Module B and Module C? Do these also become persistent as a result of loading Module A at the start of the script?

If not, is it a good practice to load them in the main script at the same time Module A is loaded i.e. before the "while" loop?

Looking forward to your replies and many thanks in anticipation.

Comment on Fastcgi and persistence in sub modules

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Re: Fastcgi and persistence in sub modules by zwon (Abbot) on Nov 28, 2012 at 15:29 UTC
If you have package A that looks like: `package A; use B; use C; ...` [download] and the script `use A; while(1) {...}` [download] Then modules A, B, and C will be loaded during script compilation time. Even if you place `use A` inside the while loop or after it (see use). If it is a good practice or not depends on your particular conditions. If you have pre-forking server running on some sort of Unix it is advisable to preload modules as it will reduce total memory usage due to COW.	[reply] [d/l] [select]
Re^2: Fastcgi and persistence in sub modules by Anonymous Monk on Nov 29, 2012 at 08:33 UTC
Exactly as you have shown. Thank you so much.	[reply]
Re: Fastcgi and persistence in sub modules by MidLifeXis (Monsignor) on Nov 28, 2012 at 15:17 UTC
IMO, if your script only depends on the functionality provided by module A, then only load module A. If your script peeks behind the covers of Module A and loads Module B and Module C from within the script, you have now made your script dependent on modules A, B, and C, and not just A. If you change the implementation of module A to use modules D and E instead, you now have to maintain the script as well. Only load what you explicitly depend on. From a persistence standpoint, fastcgi will have the dependencies also loaded. --MidLifeXis	[reply]