ubuntu mysql too many connections

I am using django with mysql on ubuntu 12.04.

It's strange that when I tried to do very simple command in mysql, it will suggest error "ERROR 1040 (HY000): Too many connections"

All I want to do is create about 20 tables using a django mysql framework, south. I am the only user connecting mysql, how come there are too many connections?

I did not change the configuration file in mysql, so the max connections should be default 150, I believe.

Could anyone help me with that? Thanks a million

update 1:
After I restart mysql server and run show processlist, I found 26 connections even though I am not doing anything. Sometimes the number would drop to 10, and come up again at 25 or something. Is that normal?

update 2:

Okay, I found what's the problem. Thanks for your help.

Answer

Okay, let me answer my problem.

Later I found that I run another python script which I forgot to terminate. The script run every 1 second to query mysql database.

+-----+------+-----------------+----------+---------+------+-------+------------------+
| Id  | User | Host            | db       | Command | Time | State | Info             |
+-----+------+-----------------+----------+---------+------+-------+------------------+
| 384 | root | localhost       | EZ_Green | Sleep   | 2682 |       | NULL             |

| 407 | root | localhost       | EZ_Green | Sleep   | 2052 |       | NULL             |
| 411 | root | localhost:47347 | NULL     | Sleep   |    3 |       | NULL             |
| 412 | root | localhost:47350 | NULL     | Sleep   |    1 |       | NULL             |
| 445 | root | localhost       | EZ_Green | Sleep   |  972 |       | NULL             |
| 448 | root | localhost       | EZ_Green | Sleep   |  882 |       | NULL             |
| 451 | root | localhost       | EZ_Green | Sleep   |  792 |       | NULL             |
| 454 | root | localhost       | EZ_Green | Sleep   |  702 |       | NULL             |
| 457 | root | localhost       | EZ_Green | Sleep   |  612 |       | NULL             |
| 460 | root | localhost       | EZ_Green | Sleep   |  522 |       | NULL             |
| 463 | root | localhost       | EZ_Green | Sleep   |  432 |       | NULL             |

| 466 | root | localhost       | EZ_Green | Sleep   |  342 |       | NULL             |
| 469 | root | localhost       | EZ_Green | Sleep   |  252 |       | NULL             |
| 472 | root | localhost       | EZ_Green | Sleep   |  162 |       | NULL             |
| 475 | root | localhost       | EZ_Green | Sleep   |   72 |       | NULL             |
| 476 | root | localhost       | EZ_Green | Sleep   |   42 |       | NULL             |
| 478 | root | localhost       | EZ_Green | Sleep   |   12 |       | NULL             |
| 479 | root | localhost       | NULL     | Query   |    0 | NULL  | show processlist |
+-----+------+-----------------+----------+---------+------+-------+------------------+

But I still don't understand why it takes so many connections and they are all sleeping? I use python thread to execute another function that query database every 1 second. There are 2 active python threads running constantly, and all the other threads are terminated when they finish. The script is here.

while True: 
    now = time.time() 
    if now < next: 
        time.sleep(next - now) 
        t = Thread(target=my_function,)
        t.start()# start a thread

    next += interval