Author: stas Date: Mon Dec 6 08:35:40 2004 New Revision: 109986 URL: http://svn.apache.org/viewcvs?view=rev&rev=109986 Log: perrin has ported Apache::SizeLimit
Added: perl/modperl/docs/trunk/src/docs/2.0/api/Apache/SizeLimit.pod Modified: perl/modperl/docs/trunk/src/docs/2.0/api/config.cfg Added: perl/modperl/docs/trunk/src/docs/2.0/api/Apache/SizeLimit.pod Url: http://svn.apache.org/viewcvs/perl/modperl/docs/trunk/src/docs/2.0/api/Apache/SizeLimit.pod?view=auto&rev=109986 ============================================================================== --- (empty file) +++ perl/modperl/docs/trunk/src/docs/2.0/api/Apache/SizeLimit.pod Mon Dec 6 08:35:40 2004 @@ -0,0 +1,172 @@ +=head1 NAME + +Apache::SizeLimit - Because size does matter. + +=head1 Synopsis + +This module allows you to kill off Apache httpd processes if they grow +too large. You can choose to set up the process size limiter to check +the process size on every request: + + # in your startup.pl, or a <Perl> section: + use Apache::SizeLimit; + # sizes are in KB + $Apache::SizeLimit::MAX_PROCESS_SIZE = 12000; # 12MB + $Apache::SizeLimit::MIN_SHARE_SIZE = 6000; # 6MB + $Apache::SizeLimit::MAX_UNSHARED_SIZE = 5000; # 5MB + + # in your httpd.conf: + PerlCleanupHandler Apache::SizeLimit + +Or you can just check those requests that are likely to get big, such +as CGI requests. This way of checking is also easier for those who +are mostly just running CGI scripts under C<ModPerl::Registry>: + + # in your script: + use Apache::SizeLimit; + # sizes are in KB + Apache::SizeLimit::setmax(12000); + Apache::SizeLimit::setmin(6000); + Apache::SizeLimit::setmax_unshared(5000); + +Since checking the process size can take a few system calls on some +platforms (e.g. linux), you may want to only check the process size +every N times. To do so, put this in your startup.pl or CGI: + + $Apache::SizeLimit::CHECK_EVERY_N_REQUESTS = 2; + +This will only check the process size every other time the process +size checker is called. + +=head1 Description + +This module is highly platform dependent, please read the +L<CAVEATS|/Caveats> section. It also does not work under threaded +MPMs, as explained below. + +This module was written in response to questions on the mod_perl +mailing list on how to tell the httpd process to exit if it gets too +big. + +Actually there are two big reasons your httpd children will grow. +First, it could have a bug that causes the process to increase in size +dramatically, until your system starts swapping. Second, it may just +do things that requires a lot of memory, and the more different kinds +of requests your server handles, the larger the httpd processes grow +over time. + +This module will not really help you with the first problem. For that +you should probably look into Apache::Resource or some other means of +setting a limit on the data size of your program. BSD-ish systems +have setrlimit() which will croak your memory gobbling processes. +However it is a little violent, terminating your process in +mid-request. + +This module attempts to solve the second situation where your process +slowly grows over time. The idea is to check the memory usage after +every request, and if it exceeds a threshold, exit gracefully. + +By using this module, you should be able to discontinue using the +Apache configuration directive B<MaxRequestsPerChild>, although you +can use both if you are feeling paranoid. Personally, I just use the +technique shown in this module and set my MaxRequestsPerChild value to +0. + +=head1 Shared Memory Options + +In addition to simply checking the total size of a process, this +module can factor in how much of the memory used by the process is +actually being shared by copy-on-write. If you don't understand how +memory is shared in this way, take a look at the extensive +documentation at http://perl.apache.org/. + +You can take advantage of the shared memory information by setting a +minimum shared size and/or a maximum unshared size. Experience on one +heavily trafficked mod_perl site showed that setting maximum unshared +size and leaving the others unset is the most effective policy. This +is because it only kills off processes that are truly using too much +physical RAM, allowing most processes to live longer and reducing the +process churn rate. + +=head1 Caveats + +This module is platform dependent, since finding the size of a process +is pretty different from OS to OS, and some platforms may not be +supported. In particular, the limits on minimum shared memory and +maximum shared memory are currently only supported on Linux and BSD. +If you can contribute support for another OS, please do. + +Currently supported OSes: + +=over 4 + +=item linux + +For linux we read the process size out of /proc/self/status. This +seems to be fast enough on modern systems. If you are worried about +performance, try setting the CHECK_EVERY_N_REQUESTS option. + +=item Solaris 2.6 and above + +For solaris we simply retrieve the size of /proc/self/as, which +contains the address-space image of the process, and convert to KB. +Shared memory calculations are not supported. + +NOTE: This is only known to work for solaris 2.6 and above. Evidently +the /proc filesystem has changed between 2.5.1 and 2.6. Can anyone +confirm or deny? + +=item *BSD* + +Uses BSD::Resource::getrusage() to determine process size. This is +pretty efficient (a lot more efficient than reading it from the /proc +fs anyway). + +=item AIX? + +Uses BSD::Resource::getrusage() to determine process size. Not sure +if the shared memory calculations will work or not. AIX users? + +=item Win32 + +Uses Win32::API to access process memory information. Win32::API can +be installed under ActiveState perl using the supplied ppm utility. + +=back + +If your platform is not supported, and if you can tell me how to check +for the size of a process under your OS (in KB), then I will add it to +the list. The more portable/efficient the solution, the better, of +course. + + + + +=head1 Threaded MPMs + +At this time, Apache::SizeLimit does not support use under threaded +MPMs, including "worker." This is because there is no efficient way +to get the memory usage of a thread, or make a thread exit cleanly. +Suggestions and patches are welcome on the mod_perl dev mailing list. + + + +=head1 Copyright + +mod_perl 2.0 and its core modules are copyrighted under +The Apache Software License, Version 2.0. + + +=head1 Author + +Doug Bagley <doug+modperl bagley.org>, channeling Procrustes. + +Brian Moseley <ix maz.org>: Solaris 2.6 support + +Doug Steinwand and Perrin Harkins <perrin elem.com>: added support for +shared memory and additional diagnostic info + +Matt Phillips <mphillips virage.com> and Mohamed Hendawi +<mhendawi virage.com>: Win32 support + +=cut Modified: perl/modperl/docs/trunk/src/docs/2.0/api/config.cfg Url: http://svn.apache.org/viewcvs/perl/modperl/docs/trunk/src/docs/2.0/api/config.cfg?view=diff&rev=109986&p1=perl/modperl/docs/trunk/src/docs/2.0/api/config.cfg&r1=109985&p2=perl/modperl/docs/trunk/src/docs/2.0/api/config.cfg&r2=109986 ============================================================================== --- perl/modperl/docs/trunk/src/docs/2.0/api/config.cfg (original) +++ perl/modperl/docs/trunk/src/docs/2.0/api/config.cfg Mon Dec 6 08:35:40 2004 @@ -34,7 +34,6 @@ Apache/RequestIO.pod Apache/RequestRec.pod Apache/RequestUtil.pod - Apache/Resource.pod Apache/Response.pod Apache/ServerRec.pod Apache/ServerUtil.pod @@ -87,7 +86,9 @@ Apache/compat.pod Apache/porting.pod Apache/Reload.pod + Apache/Resource.pod Apache/Status.pod + Apache/SizeLimit.pod )], group => 'Internal Modules', --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
