System crashes when running notebook using mojo kernel in vs code.

I tried to run mojo codes in notebook .pynb (inside vs code). I am using ubuntu 20.04 and I have 32 gb ram. I noticed ram uses suddenly increased from 6gb to 32 gb and hence system froze. This happens everytime I run my codes in vs code using mojo server and also in jupyter notebook (inside browser). What I should do to fix it?

Thanks!