The plugin plots three values:
- Wait for connection
- Idle connections
In order to authenticate to pgpool, we need to provide the username for
pcp_pool_status in plugins.conf and set .pcppass for postgres user.
env.pcppath is not specified, the plugin executes
[pgpool_*] user postgres env.host MyDBServer env.port 9898 env.user pooladm env.pcppath /path/to/pcp_pool_status env.pid_file /var/run/pgpool/pgpool.pid
There are two requirements for this plugin to work.
The first one is the Python library 'psutil'.
This can be easily installed using:
pip install psutil
... or if you prefer easy_install:
The second requirement is
pcp_pool_status, which is part of pgpool-II. This is used to access information about the pool.
It should also be said that this plugin must run on the server running pgpool since we look for processes (see below).
How the values are derived
This value is simply retreived from
Wait for connection
This one is a bit more tricky. What the plugin does is to simply look for processes named "wait for connection request" (with some filtering).
We then just count the number of occurrences and plot the value.
This works just as the above plugin, but we look for the string "idle in transaction".