Slow Startup Times on Older (v4.8 to v5.6) Linux Kernels

Older Linux kernels would block when retrieving random number entropy from the Linux /dev/random/ devices. Since Cadenza uses Java’s SecureRandom implementation to get high quality random numbers for various cryptography protocols this can cause long startup times if the OS is not providing enough entropy.

To improve this by adding more sources of entropy and therefore making startup faster as the random device blocks for a shorter time you can install the rngd daemon. It will take into account many more sources of entropy and should improve startup times as a result.

On Red Hat systems this daemon is located in the rng-tools package and after installation you need to enable its systemd service.

On newer Linux kernels this no longer occurs as the random device no longer blocks and is much faster.

You can read more background on this issue on a Redhat blog entry.