Perrin Harkins wrote:
On Thu, Feb 14, 2008 at 9:13 AM, Rafael Caceres <[EMAIL PROTECTED]> wrote:
This is the first time that NOT using "use" because it was preloaded is
mentioned. In fact, how would the modules compile (while testing for
example)?
Modules loaded into the perl interpreter at startup are still there
when the process forks, so technically you don't have to ask for them
again. I still recommend that you use() them in every module that
needs them, for testing and for documentation.
> (At the cost of having them (insibly) duplicated in all the children
> processes).
Again, this is the first time this is mentioned. It would mean that, say
10 or 20 scripts under mod_perl using DBI,DBD::Oracle,CGI and Template
would have the effect of using up to 20 times the memory footprint?
Wasn't preloading suposed to do the exact opposite?
I think that was just a wording mistake. When the process forks, the
loaded modules are shared by the operating system's copy-on-write
feature. I believe that's what he was trying to say.
- Perrin
Well, it was not exactly what I was trying to say, but undoubtedly this
reflects my incomplete personal understanding of the process anyway, and
I stand ready to be educated.
What I have until now believed is that perl "code" is in fact "data" for
the perl interpreter, and that as such it cannot really be "shared".
What I mean is that, as soon as some bit is changed in a "page" of any
perl module, that "page" is dirty and must be copied and made private to
the one child process. And since there is (in my understanding) not such
a clear separation as to which parts in "perl code" are data and which
are code, after a while one ends up with a full duplicate in each child
anyway. Probably badly explained, but not so in the general sense ?
- André
P.S. What I really meant originally, is that if the speed to make it
work was of the essence, it might be easier to (find/grep) and remove
the various use Apache-x() from the multiple modules or cgi scripts, and
put them all in the startup script. Then later one could go back and
refine things, if it makes a difference.
