If you get this error
Can't save in background: fork: Cannot allocate memory
it means that your current database is bigger than memory you have. To fix the issue enable vm.overcommit_memory:
sysctl vm.overcommit_memory=1
To have if after reboot add this line to /etc/sysctl.conf:
vm.overcommit_memory=1
Create a log:
touch /var/log/mysqld-general.log
Set the permissions:
chown mysql:mysql /var/log/mysqld-general.log
Run in mysql console:
mysql> SET GLOBAL general_log_file='/var/log/mysqld-general.log'; mysql> SET GLOBAL general_log = 1;
‘show procecclist‘ can be quite long in MySQL. Here’s simple way to filer out sleeping processes:
mysql> pager grep -v Sleep mysql> show processlist;