MESSAGE
| DATE | 2020-12-23 |
| FROM | James Smith
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| SUBJECT | Re: [Hangout - NYLXS] Confused about two development utils [EXT]
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Forgot to add - so our FCGI servers need a lot (and I mean a lot) more memory than the mod_perl servers to serve the same level of content (just in case memory blows up with FCGI backends)
-----Original Message-----
From: James Smith
Sent: 23 December 2020 11:34
To: André Warnier (tomcat/perl) ; 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 thread-safe, so if you use them in your code, at this moment the only safe way to do it is to use the Apache httpd prefork model. This means that each Apache httpd child process has its own copy of the perl interpreter, which means that the memory used by this embedded perl interpreter has to be counted n times (as many times as there are Apache httpd child processes running at any one time).
This isn’t quite true - if you load modules before the process forks 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 functions {this is the case in Linux anyway}. It also speeds up child process generation as the modules are already in memory and converted to byte code.
One of the great advantages of mod_perl is Apache2::SizeLimit which can blow away large child process - and then if needed create new ones. This is not 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 of 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 (or hit swap first)
--
The Wellcome Sanger Institute is operated by Genome Research Limited, a charity registered in England with number 1021457 and a company registered in England with number 2742969, whose registered office is 215 Euston Road, London, NW1 2BE.
--
The Wellcome Sanger Institute is operated by Genome Research
Limited, a charity registered in England with number 1021457 and a
company registered in England with number 2742969, whose registered
office is 215 Euston Road, London, NW1 2BE.
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