MySQL突然连接过多

Question

Hi I a little bit confuse to define my question title, but here is my condition and problem:

I have a cloud app created by PHP and MySQL (I use Google Cloud SQL)

My database is actively get thousand of new data every second (contain a lot of my user location and activities)

I create a PHP program to extract the insight from these data with query like:

SELECT username,time_of_activities FROM (table_name) WHERE latitude>=somevalue AND longitude>=somevalue

For every request I have several queries requested in sequential where each query will process million of rows data in my database. And the PHP program will show several insight information related with the user activities.

My problem is: Some times the PHP program failed to do the request. When the request is failed I check in CloudSQL active connection, the active connection suddenly increase 4000% just in several seconds.

This happen once the PHP request is failed. Once this happen the database will always return "Too many connection" error and I need to manually restart the CloudSQL instance.

Sometimes this PHP program will successfully run, but sometimes not and give the problem like this.

So my question is: what is wrong?

NB. I have putted the mysql_close function to make sure the connection is closed each time the PHP successfully executed the queries.

UPDATE QUESTION: I try to check the connection detail in my database and I found there are a lot of "Waiting for Insert" that happen because the database constantly get new data with insert query every second when at the same time I try to select the data.

Is this what caused my error? If yes how can the active connection suddenly 4000% times bigger while at normal condition I just have active 4-6 connections even though I constantly do the insert process to the database?

Thanks

Answer 1

Did you put the mysql_close inside a finally statement?

http://php.net/manual/en/language.exceptions.php

If you don't put it inside a finally , it may not be executed if there is an error inside the program