jake -> jdk9/dev

Andrew Dinn adinn at redhat.com
Tue May 2 09:29:27 UTC 2017

On 01/05/17 12:48, Stephen Felts wrote:
> I think this statement is very misleading. As part of this "small
> changes", jdk.attach.allowAttachSelf will be set to false and
> everyone that has self-attaching agents will start failing. So to
> repeat myself, I think that the Java community made it clear that
> this feature should not be included in JDK9.

Well, not exactly 'the Java community'. Quite a few people did object to
the EnableDynamicAgentLoading switch being introduced and defaulting to
false and as a result setting of that default was delayed until JDK10 to
ease the transition (so that the switch could be added to scripts in
advance of any need to move backwards and forwards between jdk9 and jdk10).

Now, there was also some discussion of the agent self-hoist restriction
on list but, to my recall, it was not universally addressed or
discredited as you claim. Most of the discussion was concerned with how
the process restrictions would apply. Anyway, at the very least, if you
are going to arrogate any rights on behalf of your conception of who is
'the Java community' then, as Sam Goldwyn said, please "Include me out".

I'm personally less concerned about this change of behaviour than the
EnableDynamicAgentLoading change because retaining the old behaviour
only requires a system property setting to be added to the command line.
Since that setting will be innocuous if you move back to an older
version my view is that coping with this change doesn't cause any major
transition problem.

I can understand the concern to avoid an /irremediable/ transition where
existing, important behaviour is removed. Indeed, I can easily stretch
such concern to cover an /awkward/ transition where straightforward
switching between releases is prejudiced. However, to object to a change
to new behaviour in circumstances where retaining the old behaviour
requires a relatively innocuous change seems to me to be a much less
reasonable approach. If followed repeatedly that sort of behaviour will
paint Java into a corner where we can never achieve important changes in
the JVM and JDK.


Andrew Dinn
Senior Principal Software Engineer
Red Hat UK Ltd
Registered in England and Wales under Company Registration No. 03798903
Directors: Michael Cunningham, Michael ("Mike") O'Neill, Eric Shander

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