SessionIdGeneratorBase.createSecureRandom Creation of SecureRandom instance for session ID generation
The Tomcat SessionID is obtained by calculating SHA1PRNG algorithm, SHAl algorithm requires a key, which is randomly generated when a start Tomcat, Linux generated using a random function generator / dev / random. It generates a random number corresponding to the read. / Dev / random will generate a random number based on noise, the noise is not enough if it will be blocked. Linux is the noise collected by the I / O, keypad terminals, memory usage, CPU utilization, etc., if the noise is not generated when a random number will be blocked.
The reason is not enough noise, it would increase the entropy pool.
the install RNG-Tools yum
systemctl enable rngd.service
systemctl Start rngd.service
systemctl Status rngd.service