kthreaddk in postgres uses high cpu

Question

I used Postgres in node.js project but my cpu is 100% in ubuntu server

I used this command

killall -9 kthreaddk

I stopped my project and stop postgresql service, after killing kthreaddk cpu is 0% but after 30 second kthreaddk run again and cpu will be 100% agian

what is khtreaddk and how to stopped it forever?

I try many ways that here is in stackoverflow but I can't solve it

Answer 1

kthreaddk is started by cron job. After it runs, it usually places its code in different directories and keeps updating crontab all the time.

To get rid of it follow these steps:

1. Identify which user crontab is running it.

$ cd /var/spool/cron/crontabs
# Preview each file here, e.g.
$ cat www-data
* * * * * /run/c8aaf4bea

The /run/c8aaf4bea looks weird, but do not remove it yet...

2. Block specific user from updating crontab (e.g. www-data). Edit cron.deny file

$ sudo vim /etc/cron.deny

and add a user name

www-data

Now the threaddk process is not able to edit crontab anymore.

3. Kill all the threaddk processes

$ sudo pkill -9 threaddk

4. Remove suspected line from the crontab

$ sudo vim /var/spool/cron/crontabs/www-data
* * * * * /run/c8aaf4bea     <- remove this line

5. Remove the user from cron.deny file