Samuel Merlet

I recomand this article about circular references that explain why you need a garbage collector to be enable. http://www.alexatnet.com/articles/optimize-php-memory-usage-eliminate-circular-references

In real life it's needed for background batch operation that could run for hours for example .

Note that this doesn't wroks if php run as CGI,
Persistent connections are only supported if you’re using PHP in the mod_php variety, and not the CGI wrapper.