MySQL High CPU Usage

Hi All
Centos 6 server that is showing high CPU usage in top for “mysqld” by user “mysql”

23506 mysql     20   0 1203m  58m 5384 S 142.2  0.2  22:27.25 mysqld 

Can anyone help me find out what is causing high mysqld cpu usage please?

I ran

strace -p 23506

and get the below over and over again

getsockname(65, {sa_family=AF_FILE, path="/var/lib/mysql\1"}, [28]) = 0
fcntl(65, F_SETFL, O_RDONLY)            = 0
fcntl(65, F_GETFL)                      = 0x2 (flags O_RDWR)
fcntl(65, F_SETFL, O_RDWR|O_NONBLOCK)   = 0
setsockopt(65, SOL_IP, IP_TOS, [8], 4)  = -1 EOPNOTSUPP (Operation not supported)
clone(child_stack=0x7ff050882f10, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7ff0504dc9d0, tls=0x7ff0504dc700, child_tidptr=0x7ff0504dc9d0) = 30933
select(13, [10 12], NULL, NULL, NULL)   = 1 (in [12])
fcntl(12, F_SETFL, O_RDWR|O_NONBLOCK)   = 0
accept(12, {sa_family=AF_FILE, NULL}, [2]) = 66
fcntl(12, F_SETFL, O_RDWR)              = 0


I truly don’t know if this article will help you at all because their traces are not similar to yours.

The interesting part is what he says at the end

It turns out there are known problems with mutexes in MySQL 5.5, with a couple of proposed solutions: tweak the innodb_sync_spin_loops and innodb_spin_wait_delay variables (which affect mutex loops), or manually specify a value for innodb_thread_concurrency

I wonder if that may have anything to do with your issue.

Is the high CPU usage constant? If it’s not does it coincide with when any cron jobs are due to run?

Hi, Yes it is constant… the lowest it gets is about 30% cpu and upto 180% cpu

Are there any queries in your slow query log?

Had any queries been changed or added around the time the CPU usage went crazy?

slow query log?? where do I find that?

Nothing that we know of has changed,…

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