kkjcre1p: unable to spawn jobq slave process,ORA-01034: ORACLE not available,ORA-03114: not connected to ORACLE

I observed the database connections and rman backups failing with below error.

ORA-01034: ORACLE not available 
ORA-27102: out of memory  Linux-x86_64 Error: 12: Cannot allocate memory 

and rman backups failing as below.

RMAN-12001: could not open channel ORA_DISK_1

RMAN-10008: could not create channel context

RMAN-10003: unable to connect to target database

ORA-03114: not connected to ORACLE

But database is running fine, when i check alertlog i found the message like below.

Process J000 died, see its trace file

2020-06-17T07:29:21.805339+02:00

kkjcre1p: unable to spawn jobq slave process

Cause: you might have set MEMORY_TARGET parameter and you may not have sufficient swap space required for the instance. 

Solution: as per oracle note 2356025.1, we need to allocate swap 0.75 times of memory_target size or you may need apply patch 24921392.

In my case i have reduced MEMORY_TARGET. issue got fixed.