=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padd=
ing-left:1ex">
Forgot to add - so our FCGI servers need a lot (and I mea=
n a lot) more memory than the mod_perl servers to serve the same level of c=
ontent (just in case memory blows up with FCGI backends)



-----Original Message-----

From: James Smith <>js5-at-sanger.ac.uk>

Sent: 23 December 2020 11:34

To: Andr=C3=A9 Warnier (tomcat/perl) <arget=3D"_blank">aw-at-ice-sa.com>; he.org" target=3D"_blank">modperl-at-perl.apache.org

Subject: RE: Confused about two development utils [EXT]





> This costs memory, and all the more since many perl modules are not th=
read-safe, so if you use them in your code, at this moment the only safe wa=
y to do it is to use the Apache httpd prefork model. This means that each A=
pache httpd child process has its own copy of the perl interpreter, which m=
eans that the memory used by this embedded perl interpreter has to be count=
ed n times (as many times as there are Apache httpd child processes running=
at any one time).



This isn=E2=80=99t quite true - if you load modules before the process fork=
s then they can cleverly share the same parts of memory. It is useful to be=
able to "pre-load" core functionality which is used across all f=
unctions {this is the case in Linux anyway}. It also speeds up child proces=
s generation as the modules are already in memory and converted to byte cod=
e.



One of the great advantages of mod_perl is Apache2::SizeLimit which can blo=
w away large child process - and then if needed create new ones. This is no=
t the case with some of the FCGI solutions as the individual processes can =
grow if there is a memory leak or a request that retrieves a large amount o=
f content (even if not served), but perl can't give the memory back. So=
FCGI processes only get bigger and bigger and eventually blow up memory (o=
r hit swap first)











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