Big Threads_connected (1 reply)

Hello. From time to time (couple times per month) there is a problem with the work of mysql.
First, a dramatic increase Threads_connected until it reaches the limit max_threads = 250. moreover, the usual Threads_connected value does not exceed 5.

It freezes (I waited for 10 minutes) when I try to restart it with message "Waiting for PIDS: 99125." and I have to kill process (and then restore a bunch of tables)

In the Show processlist requests attended to different tables in all sorts of different statuses: end, Locked, update, NULL