I solves the problem with pgAgent and unfortunately documentation is not sufficient.

What is the proper methodology for creating demon pgAgent under Unix? One demon at all DB jobs, or for each job should I run standalone daemon?

I was dealing with errors from the log and I did not find solution:

ERROR: Failed to query jobs table!
WARNING: Query error: SSL SYSCALL error: EOF detected

WARNING: Query error: server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.
I will be very grateful for any advice.