# PHP-FPM software Architecture



## Fleshdoom (May 14, 2013)

Hello all, does anybody have any documentation that describes PHP-FPM software architecture? I have some doubts concerning pools and master process interactions. 

In particular, I noticed that all processes of a certain pool write at their FD 3 when a request for that pool comes. ltrace clearly shows that only one process writes an HTML page, but strace instead shows a really confusing output. I have also noticed that the PHP-FPM master process listens to the same port as the pool, I think it does this, in order to know when to spawn dynamic processes. 

What I have found about PHP-FPM process interaction on the Web, presents a too high-level description, mostly oriented towards Web developers. FPM's official page describes only module directives. I would like instead to know how things are really working. 

Regards.


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