RFR: JDK-8180709: java -javaagent:agent.jar with run-time that does not contain java.instrument prints confusing error

[serguei.spitsyn at oracle.com]

Hi Gary,

I have the same concern and like Chris's suggestion.

The JMX case must be simpler as there is no need to load the agent 
library early at startup.
So that it is possible to identify the module jdk.management.agent is 
absent in the image.
I think, it happens in the java.lang.Module.Resolver.

The instrument library is loaded early at startup when the Module system 
is not
up yet, so we don't know if the module java.instrument is present or not.
The instrument library can be not found because of other reasons.

Other than that the fix looks okay to me.

Thanks,
Serguei


On 12/18/17 11:39, Chris Plummer wrote:
> Hi Gary,
>
> Overall looks good. There's one minor change you might wanted to 
> consider. It's possible the library failed to load for reasons other 
> than java.instrument not being included. I see the error output 
> already includes the error message from the failed dll_open() call, so 
> why not just suggest that it *may* be due to java.instrument missing 
> rather than implying that is known to be the reason why.
>
> thanks,
>
> Chris
>
> On 12/18/17 6:38 AM, Gary Adams wrote:
>> Here's a simple fix to include additional information when the 
>> instrument library is
>> missing from the jre and the command line requests -javaagent.
>>
>>  Issue: https://bugs.openjdk.java.net/browse/JDK-8180709
>>  Webrev: http://cr.openjdk.java.net/~gadams/8180709/webrev.00/
>>
>>
>
>