Observer cost too much CPU even if no user request at all

[raywill]

I am testing observer in a 12core machine. While there is no request, observer still cost 60% CPU of one core.

here are details (top -H):

I wrote a script to limit its cpu usage. seems that it works.

( this method requires that cgroup is enabled in your machine. create a cgroup named oceanbase)

PIDS=`top -d 10 -H -b -n1 | awk 'NR>6 { print $1,$12 }' | grep -E '(WeakReadSvr|LogStateDri|KVCacheWash|BRPC4|KVCacheRep|ObTimer|WeakReadService|ObLockWaitMgr|IODISK30|PartSerLargeCb3|CLGWR)' | awk '{print $1}'`
for i in $PIDS; do echo $i > /sys/fs/cgroup/cpu/oceanbase/tasks; done
echo 10000 > /sys/fs/cgroup/cpu/oceanbase/cpu.cfs_quota_us
> this limit max-cpu usage to 10% of a single core ( cpu.cfs_quota_us / cpu.cfs_period_us = 10000/100000 = 0.1)

# check
cat /sys/fs/cgroup/cpu/oceanbase/tasks
> should output many pids
cat  /sys/fs/cgroup/cpu/oceanbase/cpu.cfs_period_us
> should output 100000
cat  /sys/fs/cgroup/cpu/oceanbase/cpu.cfs_quota_us
> should output 10000