[RHEL] fork() System Call Slow Under Certain Workload

Solution Verified - Updated -


  • In software using fork() system call to spawn child processes to handle client queries, a situation can arise in which the fork() can take an unreasonably long time. Under an idle situation, this process of spawning a child took a couple of milliseconds. However, as parent process' memory size increases, fork() will take more and more time to complete. A majority of time appears to be spent on copying the parent's memory page table for the child.
  • Eventually, fork() can be seen to take upwards of 1-5 seconds to complete, drastically reducing performance of the overlying application.


  • Red Hat Enterprise Linux (all versions)

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