WebLogic/Node Manager Server startup is very slow on Linux

Started WebLogic (startWebLogic.sh) and it took close to 20 minutes to start and 15 minutes to start node manager. Came across below MOS document that helped resolve the issue. The slowness was due to depletion of the entropy pool provided by the OS. We need at least 500 for WebLogic.

Entropy is randomness from keyboard timings, mouse movements, and IDE timings and makes the random character data available to OS system processes through the /dev/random and /dev/urandom When there is not enough random bits left it will block and the process that are reading from it will hang until bits that are more random has been generated.

Monitoring entropy

The default size of the entropy pool is 4096 bits. You can see the size here.

[oracle@ussvr137 ~]$ cat /proc/sys/kernel/random/poolsize

4096

You can see how much entropy is available via:

[oracle@ussvr137 ~]$ cat /proc/sys/kernel/random/entropy_avail

2136

Or use watch if you want to display it every second:

watch -n 1 cat /proc/sys/kernel/random/entropy_avail

If you monitor with watch during WebLogic startup, you can check to see if entropy gets drained on the server for entropy.

Solution available in the following MOS notes.

How to diagnose a Linux entropy issue on WebLogic Server instances? (Doc ID 1574979.1)

Integrated WebLogic Server startup is very slow on Linux (Doc ID 1997349.1)

E1: OS: Linux Servers Hang or Have Delays on Any JAVA Process Affecting Performance (Doc ID 1525645.1

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