I know it may be asked before that for Magento 1 and I remember that I had this problem and fixed it by below config in php.ini
session.gc_probability = 1 session.gc_divisor = 1000 session.gc_maxlifetime = 1440
after many times I am facing a similar issue. I change session config like above but it still creates many session files (about 20-30 file in each minute). how I can fix it?