From https://www.elastic.co/blog/we-are-out-of-memory-systemd-process-limits

  • ulimit -a which reported a limit of 64140 maximum user processes.
  • /proc/sys/kernel/pid_max which reported 32768. This means that the highest PID on the system can be 32768. After that PIDs wrap. Given that ulimit allows 64140 processes per user, this number was too low, and we increased it temporarily to 131072.
  • /proc/sys/kernel/threads-max which reported 128280. As this is above the limit of maximum user processes, we kept the value.