Backend process is still runs even postmaster got killed

Backend processes are still running even if the postmaster got killed and all other server processes are exited by checking the

Postmaster status.

And the backend process is providing  the service to the client.

Is there any problems are possible? If we continue the system for a long  time with the above behavior?

Until all these kind of backend processes are exited, postmaster is failing to start.

Manual cleanup is required for these backend processes? Or is there anyway we can handle?

Regards,

Hari babu.