What are the possible effects of setting the pid.max value too high or too low?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux

Issue

  • Are there any kernel parameters that are set automatically based on the value of pid.max?
  • What are the possible effects of setting pid.max too high or too low?

Resolution

  • Changing the value of pid_max does not impact other kernel parameters.

  • In Linux, PIDs monatomically increase as new processes are allocated. (PID randomization is available in some Unixlike systems, but has never appeared in a mainline Linux kernel.)

  • If the number reaches the maximum, the next process allocated is assigned the lowest available PID.

  • If there are so many processes running concurrently that each available PID has been allocated, no further processes will be allowed to start. This is generally the only reason to increase pix_max.

  • Setting a high pid_max shouldn't have any significant impact on a system.

See also: What is the maximum value of "pid_max" which can be set in RHEL systems?

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