Tuesday, August 23, 2016

Faster Weblogic Server Startup on Linux VM


Problem


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


Cause


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 
4096

2. Check the available entropy.

$ cat /proc/sys/kernel/random/entropy_avail 
160

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)

Solution


1. Temporary Solution (Use for testing purpose)

Start the WLS Server with below startup arguments.

-Djava.security.egd=file:/dev/./urandom

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.

Change
securerandom.source=file:/dev/random

To

securerandom.source=file:/dev/urandom

iii.  Save changes and start the WebLogic Server instances.

Observation


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 !



References


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

3 comments:

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