I have a postgresql server and i'm trying to disable the overcoomit_memory on my server.

It should be simple, a single line command: sysctl -w vm.overcommit_memory=2
No need to reboot.

But as i ran the command, my server will "stop" and then the only way to get it responding again is rebooting the droplet.

Does anyone knows why it happen and how to fix?

1: https://www.postgresql.org/docs/9.6/kernel-resources.html
2: https://www.hivelocity.net/kb/how-does-memory-overcommit-affect-postgresql/
3: http://engineering.pivotal.io/post/virtual_memory_settings_in_linux_-_the_problem_with_overcommit/