Re: swingbench connection issue

  • From: De DBA <dedba@xxxxxxxxxx>
  • To: kylelf@xxxxxxxxx
  • Date: Wed, 14 Nov 2012 15:01:26 +1000

Kyle,

I don't know charbench, or how it uses randomness, but perhaps this may 
go some way to explaining it:

(quote from http://linux.about.com/library/cmd/blcmdl4_urandom.htm )

"...When the entropy pool is empty, reads to /dev/random will block 
until additional environmental noise is gathered."

( from wikipedia )
"... A counterpart to /dev/random is /dev/urandom 
("unlocked"/non-blocking random source[4]) which reuses the internal 
pool to produce more pseudo-random bits. This means that the call will 
not block, but the output may contain less entropy than the 
corresponding read from /dev/random. "

As I understand it, at some point on the one database you could have 
exhausted the entropy pool and the process blocks until some more 
entropy is gathered? Perhaps due to better performance on that one 
database than the other, or different test data settings?

Usn/Martin Klier also has some suggestions on his blog on how to ensure 
that Oracle JDBC won't exhaust the entropy on a server: 
http://www.usn-it.de/index.php/2009/02/20/oracle-11g-jdbc-driver-hangs-blocked-by-devrandom-entropy-pool-empty/


Hth,
Tony

On 13/11/12 4:17 PM, kyle Hailey wrote:
> This seems to have solved it
> https://kr.forums.oracle.com/forums/thread.jspa?threadID=941911
>
> *rm /dev/random*
> *ln -s /dev/urandom /dev/random
>
>
> *strange that the problem arises with one database on the box but not
> another on the same box
>
>
> --
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>
>
>
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