In general, if the system is functioning normally but starts freezing during certain operations (somehow related to encryption), it is a good idea to check the amount of available entropy on the server/client using the command:

cat /proc/sys/kernel/random/entropy_avail

The available entropy should be in the thousands — if it is lower, this may be the cause of the freezing.

When running ABRA Flexi on Linux servers, it is important to ensure a sufficient amount of "entropy" is available. The specific distribution and Java version determine what is configured as the entropy source. Typically, this is /dev/random, which blocks when entropy runs low.

The best solution we have found is to use the rng daemon.

CentOS 8: rngd is active in the system by default

CentOS 7: yum -y install rng-tools; systemctl enable --now rngd

CentOS 6: yum -y install rng-tools; v /etc/sysconfig/rngd doplnit EXTRAOPTIONS="-r /dev/urandom" ; service rngd start; chkconfig rngd on