Is your WebLogic Server slooow? Might be because of low entropy

Peter Lorenzen

I have written a new more detailed post about this πŸ™‚

{ 7 comments… read them below or add one }

Jacco H. Landlust February 13, 2013 at 23:07

Usually I change securerandom.source in $JAVA_HOME/jre/lib/security/ to file:/dev/./urandom . This means that whoever runs WLS doesn’t have to bother about this parameter πŸ™‚ It is supposed to be a little less random than /dev/random , but I really don’t know what is the real risk in that.

Also I noticed that you have more issues with slowness caused by low entropy on VM’s than on physical hardware.

Anyway, great post. You have a new subscription to your blog πŸ™‚

Peter Lorenzen February 14, 2013 at 20:20

Thanks Jacco. I updated the post with your tip πŸ™‚

KM May 9, 2013 at 17:11

Hi Peter,

Could you please expand on why


should not be used in production … ? Is it because the gets overwritten? Performance issues?

I’m using

in with “securesource.source=file:/dev/urandom” commented out, which seems to work, but is that the right way of doing things?

Many thanks!

Peter Lorenzen May 10, 2013 at 09:57

It is not real random numbers so it is not as secure. I do not know how big a risk this is.
Oracle writes “Note that this workaround should not be used in production environments because it uses pseudo-random numbers instead of genuine random numbers.”
Regards Peter

Edwin Biemond September 15, 2013 at 19:39


Great post, rngd also helps for me

# install the package, its probably already there
yum install rng-tools

After installation you can try to start and get such error:
service rngd start

Starting rngd: can’t open entropy source(tpm or intel/amd rng)
Maybe RNG device modules are not loaded

Edit /etc/sysconfig/rngd
EXTRAOPTIONS=”-r /dev/urandom -o /dev/random -b”

# start the service
service rngd start

# also when it reboots
chkconfig rngd on

# check the settings
chkconfig –list rngd


Peter Lorenzen September 15, 2013 at 20:00

Thanks for the tip Edwin πŸ™‚

Matthew V July 2, 2018 at 07:00

Thanks for the tip on, it have been customized for my case on ODI 12 runs (on :
if [ “X${USER_MEM_ARGS}” = “X” ] ; then
USER_MEM_ARGS=”-Xms1024m -Xmx4096m”

In addition, an interesting comparision between randow and urandom :

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