CPUUtilization high and jobs failed - AWS - knime server 4.9

i know its good but… knime supposed to play role in both ways…

i guess i found isseu -
swap memory not freeing after workflow execution done , even after closing knime. - i need to reboot for this…
every ttime i check swape memory is above 85%
then i reboot machine then it come back to normal and jobs run fine…

but after many job execution again swap memory above 85%

any solution for this…