[jboss-as7-dev] Changed arguments…can we do better ? :P

Stuart Douglas stuart.w.douglas at gmail.com
Wed Feb 1 16:17:07 EST 2012


Did you consider having byteman instrument the Class Loaders in the target vm, to always delegate to the system class loader if the class being loading starts with "org.byteman" ? 

I am pretty sure this is how JProfiler gets around the need for this setting.  

Stuart

On 01/02/2012, at 11:14 PM, Andrew Dinn wrote:

> Someone just mentioned that Max posted this question regarding AS7 startup:
> 
>> Going over the AS7.1 server and how startup arguments has changed we
>> noticed besides the -logmodule not being needed the following two was
>> added:
>> 
>> -Djboss.modules.system.pkgs=org.jboss.byteman
>> -Djava.awt.headless=true
>> . . .
>> Any reason why byte man gets added and not the others ?
> 
> Yes. If you don't add this at startup then the module loader will hide 
> all the Byteman classes from all JBoss classloaders. This means that you 
> cannot decide to install a Byteman agent after AS startup in order to 
> debug/trace behaviour in a broken App Server. It just won't work (TM). 
> That's going to give our support team (not to mention our developers who 
> need to use Byteman for testing) a major headache.
> 
> Of course, we could always advise all AS7 users to configure this 
> setting in their own startup and leave it undefined by default but in 
> practice that's just going to be a FAIL. David Lloyd and I discussed 
> this some months back (July 11?) and having checked that adding this to 
> the startup had *negligible* overhead it was added as a default.
> 
> Also, I think the idea of adding this via a properties file sounds nice 
> at first but actually it is just splitting up the config by another 
> name. One file to rule them all . . .
> 
> 
> regards,
> 
> 
> Andrew Dinn
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