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Log Error “fork: Cannot allocate memory”

Last updated: 2022-04-06 20:30:26

    Error Description

    Log contains the error message “fork: Cannot allocate memory”.

    Possible Reasons

    This issue may be caused by excessive threads. If a new thread is created after the pid_max value is reached, the error message “fork: Cannot allocate memory” appears.


    1. Perform the troubleshooting procedure to check the memory utilization.
    2. Check the number of threads and modify the pid_max configuration.

    Troubleshooting Procedure

    1. Check the memory utilization as instructed in High Memory Utilization. If the memory utilization is normal, proceed to the next step.
    2. Run the following command to obtain the value of pid_max.
      sysctl -a | grep pid_max

    The default value of pid_max is 32768, as shown below:

    3. Run the following command to view the total number of threads.

    pstree -p | wc -l

    When the total number of threads has reached pid_max, a new thread will cause the “fork: Cannot allocate memory” error.


    You can use the ps -efL command to locate the programs for which many threads are running.

    1. Change the kernel.pid_max value in the /etc/sysctl.conf configuration file to 65535 to increase the number of threads. The result should be as follows:
    2. Run the following command for the configuration to take effect immediately.
      sysctl -p
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