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Plack::Middleware::SizeLimit - Terminate processes if they grow too large


    use Plack::Builder;

    builder {
        enable SizeLimit => (
            max_unshared_size_in_kb => '4096', # 4MB
            # min_shared_size_in_kb => '8192', # 8MB
            # max_process_size_in_kb => '16384', # 16MB
            check_every_n_requests => 2,
            log_when_limits_exceeded => 1,
            callback => sub {
               my ($size, $share, $unshared) = @_;


This middleware is a port of the excellent Apache::SizeLimit module for multi-process Plack servers, such as Starman, Starlet, Gazelle and uWSGI.

This middleware only works when the environment psgix.harakiri is set to a true value by the Plack server. If it's set to false, then this middleware simply does nothing.

You must use at least version 0.2006 of Starman (July 2010), and 0.19 of Starlet (June 2013). Earlier versions ignore the flag to stop the process.



The maximum amount of unshared memory the process can use; usually this option is all one needs.

Experience on one heavily trafficked mod_perl site showed that setting this option 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.


Sets the minimum amount of shared memory the process must have.


The maximum size of the process, including both shared and unshared memory.


Since checking the process size can take a few system calls on some platforms (e.g. linux), you may specify this option to check the process size every N requests. The default value for N is 1, i.e. to check after the processing of every request.


When true, the middleware will log a warning whenever it signals to the server that the process is to be terminated. This is false by default.


A reference to a subroutine that takes the process size information. This can be used to feed this information into a monitoring system, such as statsd.


Starman, Starlet, Gazelle


Audrey Tang <cpan@audreyt.org>


This work is under the CC0 1.0 Universal license.

To the extent possible under law, 唐鳳 has waived all copyright and related or neighboring rights to Plack::Middleware::SizeLimit.

This work is published from Taiwan.