Tuesday, August 23, 2016

Faster Weblogic Server Startup on Linux VM


Weblogic server running on a Linux Virtual Machine is stuck while startup. For instance a Oracle SOA 12.2.1 weblogic manage server may take upto 12 minutes to startup on a Linux VM. A Weblogic 12C manage Server running nothing may take upto 4 minutes to start. The virtual machines are all equipped with enough CPUs and memory. 

Applies To 

Weblogic 12.1.x,12.2.x
RHEL X86,X86_64 Virtual Machines


Linux has two devices to provide random data at any time: /dev/random and /dev/urandom. Both ways should be secure enough to use them in generating PGP keys, ssh challenges, and other applications where secure random numbers are required. Starting on kernel 2.6, default entropy is 4096 bits and problem arises when the entropy available on the system is minimum (around 100 bits or less).

How to verify if you are encountering this issue?

1. Check the default system entropy

$ cat /proc/sys/kernel/random/poolsize 

2. Check the available entropy.

$ cat /proc/sys/kernel/random/entropy_avail 

3. On previous example, entropy is too low.

Monitor the current entropy of the system by using the following command:

$ for i in $(seq 500); do cat /proc/sys/kernel/random/entropy_avail ; sleep 5; done

4. Start a WebLogic server instance. You should see that entropy decreases or stalls (use script in step 3)


1. Temporary Solution (Use for testing purpose)

Start the WLS Server with below startup arguments.


Override the JAVA_OPTIONS environment variable before starting WebLogic Server via shell scripts.

export JAVA_OPTIONS="${JAVA_OPTIONS} -Djava.security.egd=file:/dev/./urandom"

Start the Weblogic Server and note the timings!

2. Permanent Solution (Use if Step 1 works)

If the above solution works it is time to setup the fix permanently in the env. The fix can be applied in the JAVA_HOME the Weblogic server refers to.

i.   Edit the Java Security Properties file ($JAVA_HOME/jre/lib/security/java.security)

ii.  The securerandom.source property specifies the source of seed data for secure random.




iii.  Save changes and start the WebLogic Server instances.


We could see the startup tiings for Weblogic server improved dramatically. For instance the SOA Manage Server now took only less than 3 minutes as against 12 minutes before the fix was applied! The bare Weblogic manage servers took less tha 20 seconds to start !


How to Diagnose a Linux Entropy Issue on WebLogic Server Instances (Doc ID 1574979.1)


  1. Your way of explanation is so interesting thank you for sharing useful content


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