Logs missing from files

I am using a custom logger(basically a script snap in which i write) which logs to a certain file . This logger is used in 4 pipelines of a project . The problem is that when I run all the pipelines together at same time logs come initially to the file but after a certain stage they donot occur. Can any one throw some light on this issue. What might be the problem?

PS the logger is said to be thread safe. ( I have integrated java.util.logger in the script snap)