mysql processes still alive from processlist

[ZER09]

I have this in my my.cnf

wait_timeout=1800
interactive_timeout=1800;
net_read_timeout=1800;
net_write_timeout=1800

but when i execute

show processlist;

I have processes that still running more than 4500sec even they are in 'Sleep' command.

please help about this, thank you.

[rubberman]

Just because a process is "sleeping" doesn't mean it isn't running. It is just waiting for a timer or wakeup event to happen.

[ZER09]

but i thought if it reached a certain timeout, it should be killed to free-up a connection slot.