Re: [OT] Massive Startup Time after Server Reboot

[Christopher Schultz <ch...@christopherschultz.net>]

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Markus,

On 5/18/19 17:39, info@flyingfischer.ch wrote:
> apt-get install haveged update-rc.d haveged defaults
> 
> This increases the system entropy for random generation and reduces
> boot time for Tomcat considerably.

I'm a -1 on this solution because it takes a reliable source of
entropy and converts it into an unreliable source of entropy. There is
a reason that *NIX* systems usually have both /dev/random (a good,
secure source of randomness) and /dev/urandom (a *fast* source of
randomness which is reasonably good).

When there are reasons to use /dev/random -- such as generating a new
long-lived encryption key like PGP, RSA, ECC, etc. -- it's important
that these kinds of "artificial" sources of randomness aren't used.
That's why we don't use /dev/urandom for those purposes.

But haveged basically turns /dev/random into /dev/urandom and
therefore programs have no choice.

It's better to leave hadeged out of the mix and choose the right
source of randomness for your application.

- -chris

> Am 18.05.19 um 22:18 schrieb Rainer Jung:
>> Most likely it hangs waiting for enough entropy for random
>> number generator seeding.
>> 
>> Try whether the problem goes away if you add
>> 
>> -Djava.security.egd=file:/dev/urandom
>> 
>> to you process flags. If you are using older Java than Java 8
>> (not possible for Tomcat 9 but just in case you also have older
>> software stacks running), then it would be
>> 
>> -Djava.security.egd=file:/dev/./urandom
>> 
>> The cryptic /./ is not a typo, you would need it for Java before
>> Java 8.
>> 
>> If this doesn't help, then you should try capturing a few stack
>> dumps (thread dumps) during the long startup time. People here
>> can help interpret them.
>> 
>> Regards,
>> 
>> Rainer
>> 
>> Am 18.05.2019 um 21:55 schrieb Jerry Malcolm:
>>> This is a weird one.  It started a few months ago.   I have TC
>>> 9 running on Windows Server 16.  After I reboot the entire
>>> server, Tomcat takes forever on startup.  It normally starts in
>>> about 30 seconds.  But after a server reboot it takes up to 15
>>> minutes... chugging along at a snail's pace starting up all of
>>> the apps on all of the virtual hosts.  It always finally gets
>>> there with everything successfully running.  Other servers on
>>> the same box (Apache, JAMES, ISC BIND, MySQL) don't have any
>>> problem starting up.  CPU, Disk, Memory, etc. usages are barely
>>> showing on the performance graphs. There's nothing in the
>>> Catalina log or system.err other than showing a couple of
>>> minute gap in the time stamp between each app as it starts up.
>>> If I need to reboot again later, it boots again in about 30 sec
>>> as expected.
>>> 
>>> First question... any ideas off the top of your head that might
>>> be causing this?
>>> 
>>> Second question... is there any other logging I can turn on
>>> that might explain what TC is blocking on?
>>> 
>>> Thanks.
>>> 
>>> Jerry
>> 
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