php - How can I see how many MySQL connections are open?

Question

How can I see how many connections have been opened during the current request via mysql_connect in PHP running on Apache?

I know that if I call mysql_connect function 100 times with the same parameters, it will always return the same connection link. It will not start new connection once the connection already exists.

But I just want to make sure mysql_connect is not starting a new one.

I am working with a legacy system which contains many mysql_connect function calls.

Is there any setting in Apache or is there any way I can log this number of connections in Apache or MySQL log file?

Answer 1

I think there are a couple of ways:

SHOW STATUS WHERE `variable_name` = 'Threads_connected'

or you can do a SHOW PROCESSLIST and find out unique values in the Id column. In old PHP API mysql, there is mysql_list_processes function that does the same as SHOW PROCESSLIST, too.

But first one should work for you. And perhaps you might like to check on other STATUS variables