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From Kevan Miller <kevan.mil...@gmail.com>
Subject Re: Startup time delay in Ubuntu server
Date Tue, 13 Jan 2009 12:55:24 GMT

On Jan 13, 2009, at 5:49 AM, eros wrote:

>
>
>
>> I think you have a problem with system entropy that's causing a
>> problem generating pseudo-random numbers.
>>
>> While the server startup was stalled, I sent a kill -3 signal to the
>> server process (think I mentioned doing this earlier in this thread)
>> and got the following thread stack:
>
> Yep that's it!

Cool.

>
>
> I tried the kill -3 thingy (didn't know about it, thanks!) and got  
> the a
> stack trace just like yours. Having the server do some expensive
> calculations while tomcat starts up seems to improve the situation a  
> bit
> (probably because this activity generates entropy).
>
> The thing that really does the trick is:
>
> mv /dev/random /dev/random.bak
> mv /dev/urandom dev/random
>
> even if I don't particularly like the security implications of this.

Right. From what I've read it's possible that we could also change the  
algorithm being used (e.g. SHA1 which apparently does not use /dev/ 
random) to reduce the likelihood of this happening (prolly with some  
tradeoff on security). I'd also want to better understand what's going  
on in the KeystoreUtil static initializer -- it's new code for me...

>
> The problem seems to be working on underused servers and is  
> apparently more
> debian-related (see
> http://n0tablog.wordpress.com/2007/11/24/running-out-of-entropy-in-debian-etch/)
> than geronimo-related.

You'll want to drop the trailing ')' for this url to work. Thanks for  
the pointer. I've see this basic problem occur on non-debian systems  
also. I'm no entropy expert (though my wife might argue about  
that... ;-).

--kevan


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