09-23-2009
This is akin to asking "how many boxes can I transport on a boat".
It all depends on a lot of factors. What kind of boxes are they? How big are they? What kind of boat are you using to transport the boxes? There's also a question of where your limitations are. For instance, if the boxes are very light, volume is obviously going to be the limiting factor. If they are excessively heavy, then weight might be the issue.
In regards to your question, the same answer applies. What kind of Apache instances are they? If they are low-RAM but CPU heavy processes, then obviously CPU will be your limiting factor. If they eat up a lot of RAM, but little CPU, then RAM is your limit. The same thing goes for I/O.
It's also a question of your architecture. For instance, Apache2 with prefork has a hard limit of ~64k processes, so you can never go beyond that, not that you're likely to reach that figure in any reasonable scenario anyway. Threaded Apache2 doesn't have the same kind of limits, but have limits of their own.
It's also a matter of how you set up Apache. I've seen systems where the limiting factor was neither CPU nor RAM, but the fact that Apache had to spend all its time spawning new processes.
The simple answer to your question is the following, how much RAM does each process consume, and how much RAM do you have available?
For instance, if each process takes 50MB RAM and you have 2GB RAM, you can run 40 processes.
Now, again, this is NOT a simple question to answer, and the only way for you to reliably find out is to take a look at YOUR setup and do some calculation work.
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LEARN ABOUT REDHAT
apache::build
Apache::Build(3) User Contributed Perl Documentation Apache::Build(3)
NAME
Apache::Build - Methods for locating and parsing bits of Apache source code
SYNOPSIS
use Apache::Build ();
my $build = Apache::Build->new;
# rebuild mod_perl with build opts from the previous build
% cd modperl-2.0
% perl -MApache::Build -e rebuild
DESCRIPTION
This module provides methods for locating and parsing bits of Apache source code.
Since mod_perl remembers what build options were used to build it, you can use this knowledge to rebuild it using the same options. Simply
chdir to the mod_perl source directory and run:
% cd modperl-2.0
% perl -MApache::Build -e rebuild
If you want to rebuild not yet installed, but already built mod_perl, run from its root directory:
% perl -Ilib -MApache::Build -e rebuild
METHODS
new Create an object blessed into the Apache::Build class.
my $build = Apache::Build->new;
dir Top level directory where source files are located.
my $dir = $build->dir;
-d $dir or die "can't stat $dir $!
";
find
Searches for apache source directories, return a list of those found.
Example:
for my $dir ($build->find) {
my $yn = prompt "Configure with $dir ?", "y";
...
}
inc Print include paths for MakeMaker's INC argument to "WriteMakefile".
Example:
use ExtUtils::MakeMaker;
use Apache::Build ();
WriteMakefile(
'NAME' => 'Apache::Module',
'VERSION' => '0.01',
'INC' => Apache::Build->new->inc,
);
module_magic_number
Return the MODULE_MAGIC_NUMBER defined in the apache source.
Example:
my $mmn = $build->module_magic_number;
httpd_version
Return the server version.
Example:
my $v = $build->httpd_version;
otherldflags
Return other ld flags for MakeMaker's dynamic_lib argument to "WriteMakefile". This might be needed on systems like AIX that need spe-
cial flags to the linker to be able to reference mod_perl or httpd symbols.
Example:
use ExtUtils::MakeMaker;
use Apache::Build ();
WriteMakefile(
'NAME' => 'Apache::Module',
'VERSION' => '0.01',
'INC' => Apache::Build->new->inc,
'dynamic_lib' => {
'OTHERLDFLAGS' => Apache::Build->new->otherldflags,
},
);
AUTHOR
Doug MacEachern
mod_perl-1.99_07 2002-08-28 Apache::Build(3)