To answer my own question, this functionality is used to allow
detach/reattach from {cl}hsdb. Which seems to work on linux but not
windows with this code removed.
The next question is whether this is useful functionality to justify all
this code (900+ and this new code that Magnus has added). Can't you
just exit and restart the clhsdb process on the core file or process?
For the record, this is me playing with python to remove this code.
http://cr.openjdk.java.net/~coleenp/2020/01/webrev/index.html
Thanks,
Coleen
On 3/30/20 3:04 PM, coleen.phillim...@oracle.com wrote:
I was wondering why this is needed when debugging a core file, which
is the key thing we need the SA for:
/** This is used by both the debugger and any runtime system. It is
the basic mechanism by which classes which mimic underlying VM
functionality cause themselves to be initialized. The given
observer will be notified (with arguments (null, null)) when the
VM is re-initialized, as well as when it registers itself with
the VM. */
public static void registerVMInitializedObserver(Observer o) {
vmInitializedObservers.add(o);
o.update(null, null);
}
It seems like if it isn't needed, we shouldn't add these classes and
remove their use.
Coleen
On 3/30/20 8:14 AM, Magnus Ihse Bursie wrote:
No opinions on this?
/Magnus
On 2020-03-25 23:34, Magnus Ihse Bursie wrote:
Hi everyone,
As a follow-up to the ongoing review for JDK-8241618, I have also
looked at fixing the deprecation warnings in jdk.hotspot.agent.
These fall in three broad categories:
* Deprecation of the boxing type constructors (e.g. "new Integer(42)").
* Deprecation of java.util.Observer and Observable.
* The rest (mostly Class.newInstance(), and a few number of other
odd deprecations)
The first category is trivial to fix. The last category need some
special discussion. But the overwhelming majority of deprecation
warnings come from the use of Observer and Observable. This really
dwarfs anything else, and needs to be handled first, otherwise it's
hard to even spot the other issues.
My analysis of the situation is that the deprecation of Observer and
Observable seems a bit harsh, from the PoV of jdk.hotspot.agent.
Sure, it might be limited, but I think it does exactly what is
needed here. So the migration suggested in Observable (java.beans or
java.util.concurrent) seems overkill. If there are genuine threading
issues at play here, this assumption might be wrong, and then maybe
going the j.u.c. route is correct.
But if that's not, the main goal should be to stay with the current
implementation. One way to do this is to sprinkle the code with
@SuppressWarning. But I think a better way would be to just
implement our own Observer and Observable. After all, the classes
are trivial.
I've made a mock-up of this solution, were I just copied the
java.util.Observer and Observable, and removed the deprecation
annotations. The only thing needed for the rest of the code is to
make sure we import these; I've done this for three arbitrarily
selected classes just to show what the change would typically look
like. Here's the mock-up:
http://cr.openjdk.java.net/~ihse/hotspot-agent-observer/webrev.01
Let me know what you think.
/Magnus
