On 3/31/20 4:55 PM, Chris Plummer wrote:
On 3/31/20 1:32 PM, coleen.phillim...@oracle.com wrote:
On 3/31/20 12:19 PM, Poonam Parhar wrote:
Hello Coleen,
Does the removal of this code only impact the 'reattach'
functionality, and it does not affect any commands available in
'clhsdb' once it is attached to a core file? If that's true, then I
think it should be okay to remove this code.
Hi Poonam, Thank you for answering. Yes, this patch only removes the
reattach functionality. I tried out the other clhsdb commands from
your wiki page, and they worked fine, including object and heap
inspection.
I'm trying to understand exactly when all these static initializes are
triggered. Is it only after you do an attach?
The implementation of clhsdb reattach is exactly the same as doing a
detach followed by an attach to the same process. I'm not sure how
much value it has, but I think in general the removal of this code
means you can't detach and then attach to anything, even a different
pid. So "detach" might as well become "detach-and-exit", because your
clhsdb session is dead once you detach. Do we really want to do this?
Well, that was my question. It seems like you could just exit and start
up jhsdb again and that's more like something someone would do just as
easily. Given the use cases that we've seen from sustaining, this
appears to be unneeded functionality.
The original mail was proposing adding more code to work around the
deprecation messages. It seems like more code should not be added for
something that is unused.
thanks,
Coleen
Chris
Thanks,
Coleen
Thanks,
Poonam
On 3/31/20 5:34 AM, coleen.phillim...@oracle.com wrote:
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
