apache with libapache2-mod-fastcgi uses unlimited memory on http multipart streaming

[Markus Bienst]

Hello,
it seems to be a general issue with libapache2-mod-fastcgi serving big responses like long running motion-jpeg streams via http.
The Apache Processes combined with mod-fastcgi will eat up unlimited memory till system crash during transmission. Using the Module 'libapache2-mod-fcgid', the Apache Processes will keep their Memory usage. That is what i expect, but mod-fcgid is not a suitable replacement for our application.

To investigate the Apache Memory Consumption with our fcgi application, i used a modifed version (included in the attachment) of tiny-fcgi.c from http://www.fastcgi.com/devkit/doc/fcgi-devel-kit.htm to generate continous content.
As a test data sink i used httpservertest.py.

The Package in Ubuntu 15.04 has the same issue.

Note: tiny-fcgi.c needs libfcgi-dev.

1.
The Ubuntu Release:
Description: Ubuntu 12.04.5 LTS
Release: 12.04

2.
The Package:

Package: libapache2-mod-fastcgi
Status: install ok installed
Priority: optional
Section: non-free/web
Installed-Size: 256
Maintainer: Ubuntu Developers <email address hidden>
Architecture: i386
Source: libapache-mod-fastcgi
Version: 2.4.7~0910052141-1
Depends: apache2.2-common (>= 2.2.4), libc6 (>= 2.4)
Conffiles:
 /etc/apache2/mods-available/fastcgi.load d653aa349dd9978fea3c933833b4b93f
 /etc/apache2/mods-available/fastcgi.conf 87bcf3377d158797580ef2d9271562fd
Description: Apache 2 FastCGI module for long-running CGI scripts
 This is a FastCGI module for the Apache 2.x web server. FastCGI is an
 open standard for communicating between a web server and a long-running
 web application. CGI scripts supporting FastCGI can be started as a
 daemon and process multiple requests without restarting. This is
 particularly useful for scripts written in languages like Perl, as it
 saves the cost of recompiling the scripts and its loaded modules with
 each invocation.
Original-Maintainer: Tatsuki Sugiura <email address hidden>
Homepage: http://www.fastcgi.com/