MySQL连接太多

Question

I'm preparing chat system with comet style programming.It delays(sleeps) page for a 60 second and I use mysql queries in this loop and it approximately sends 245.000 queries to mysql. Mysql status is like below:

Aborted_connects - 179391
Connections - 15673040
Max_used_connections - 59
Threads_connected - 6

May it be problem that Connections tab is 15 million, but I can't kill them. Can I solve this problem adding mysql_close to end of while() ?

set_time_limit(60);
mysql_connect("...");
while(true){
  usleep(60000);
  clearstatcache();
  mysql_query("...");
  mysql_close();//<= this one
}

Answer 1

There are few things.

1. Your code somehow connects to mysql way too much. Debug your code.
2. Try to pool your connections. Read this Connection pooling in PHP

Answer 2

Seeing your code and your problem, we should take into account and differentiate between connection and query .

It's useless to close the conection on the while true loop and it's an error.

Your code should be something like this:

mysql_connect("...");
while(true){
  //do stuff like:
  mysql_query("...");
}
//in case of we exit while true...
mysql_close();//<= this one

If we read the mysql_close manual, we can find this:

Using mysql_close() isn't usually necessary, as non-persistent open links are automatically closed at the end of the script's execution.

So, for now, don't take into account when to close the mysql_connection. We should see how the connections are being created and where.

I recomend you to check inside your MySQL and debbug it. You can with this commands:

show status where `variable_name` = 'Threads_connected';

With this you can check the current connections. Also you could check with:

show processlist;

And you will see all the process list.

Maybe with that we can start to debug and find the problem :)