We are troubleshooting a MySQL issue where some queries are taking a very long time complete and I see many of these entry in /var/log/messages:
Jan 28 05:52:15 64455-alpha01 kernel: [2529273.616327] INFO: task mysqld:4123 blocked for more than 120 seconds. Jan 28 05:52:15 64455-alpha01 kernel: [2529273.616525] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. Jan 28 05:52:15 64455-alpha01 kernel: [2529273.616813] mysqld D 000000000000000d 0 4123 3142 0x00000080
What does it mean? How does it affect that MySQL thread (4123 is the thread id?)
The value in
/proc/sys/kernel/hung_task_timeout_secs when I checked now is:
$ cat /proc/sys/kernel/hung_task_timeout_secs 120
I specifically would like to know how does it affect the process?
I read in a forum that it means it happens when that process is holding up too much memory.