Why Is PHP-FPM Only Using One Process?

Question

Looking at my PHP-FPM stats page, it looks like only one process is handling all of the connections right now.

My guess is that requests are being executed so quickly, thus far, that it doesn't need to use another process yet. Would this be the case?

Here's what I'm seeing in my PHP-FPM stats page:

pool                    www
process manager         static
start since             432796
accepted conn           90399
listen queue            0
max listen queue        1
listen queue len        128
idle processes          63
active processes        1
total processes         64
max active processes    6
max children reached    0

This is what my PHP-FPM Config looks like:

[General]
 pid = /var/run/php5-fpm.pid
 error_log = /var/log/php5-fpm.log
 syslog.ident = php-fpm
 syslog.facility = 24
 log_level = unknown value
 emergency_restart_interval = 0s
 emergency_restart_threshold = 0
 process_control_timeout = 0s
 process.max = 0
 process.priority = undefined
 daemonize = yes
 rlimit_files = 30000
 rlimit_core = 0
 events.mechanism = epoll

[www]
 prefix = undefined
 user = www-data
 group = www-data
 listen = 127.0.0.1:9000
 listen.backlog = 128
 listen.owner = undefined
 listen.group = undefined
 listen.mode = undefined
 listen.allowed_clients = 127.0.0.1
 process.priority = undefined
 pm = static
 pm.max_children = 64
 pm.start_servers = 8
 pm.min_spare_servers = 4
 pm.max_spare_servers = 10
 pm.process_idle_timeout = 10
 pm.max_requests = 12800
 pm.status_path = /fpm
 ping.path = undefined
 ping.response = undefined
 access.log = undefined
 access.format = undefined
 slowlog = /var/log/www.log.slow
 request_slowlog_timeout = 5s
 request_terminate_timeout = 120s
 rlimit_files = 30000
 rlimit_core = 0
 chroot = undefined
 chdir = /
 catch_workers_output = yes
 security.limit_extensions = .php .phar

Answer 1

Why Is PHP-FPM Only Using One Process?

Because... 1 is enough. But it doesn't mean that the number of active processes always is 1.

Split the terminal into 2 regions: in the first one type:

$ watch 'lynx -dump http://domain.com/fpm'

and in the second one, try something like this:

$ ab -c 1000 -n 10000 http://domain.com/fpm

then see what's going on in the first region:

pool:                 www
process manager:      dynamic
start time:           04/Sep/2012:23:19:24 +0700
start since:          3441
accepted conn:        42296
listen queue:         0
max listen queue:     8
listen queue len:     128
idle processes:       18
active processes:     3
total processes:      21
max active processes: 21
max children reached: 0