Strange behaviour in DeferredCompletionFailureHandler

[Dmitry Batkovich]

ok, but what's about WeakHashMap? I've lots of stale keys which should be
collected but they are not because they had strong references in values.

On Mon, Nov 12, 2018 at 6:57 PM Jan Lahoda <jan.lahoda at oracle.com> wrote:

> Hi Dmitry,
>
> The overall goal is to avoid CompletionFailures to be thrown to the user
> code. This requires to "spit" a Symbol into user code version and an
> javac internal version and to use the user-code version while in user
> code, and javac internal version while in javac. (Because javac needs
> the CompletionFailures for correctness.)
>
> There was an issue that even "hypothetical" Symbol were kept in the
> maps, which should be fixed now. Please see:
> https://bugs.openjdk.java.net/browse/JDK-8209055
>
> Please let me know how it works in your usecase.
>
> Thanks,
>      Jan
>
> On 12.11.2018 16:10, Dmitry Batkovich wrote:
> > Hi all,
> >
> > I've faced with javac 11 performance problem
> > in DeferredCompletionFailureHandler. I have a project with google dagger
> > dependency injection and with some javac task listener (You may see
> > https://youtrack.jetbrains.com/issue/IDEA-201978). In this case I see
> > lots FlipSymbolDescription#flip() traces in compiler profile snapshot.
> > I've tried to investigate the problem by myself and found next things:
> >
> > 1)
> > Map
> com.sun.tools.javac.code.DeferredCompletionFailureHandler.Handler#class2Flip
> > produces memory leaks because keys of the map are present as a part of
> > value object. So, keys are always strongly referenced. And usage of
> > WeakHashMap is useless here.
> >
> > 2)
> com.sun.tools.javac.code.DeferredCompletionFailureHandler.Handler#class2Flip
> > does nothing. Any information inside FlipSymbolDescription is never used
> > (DefferedCompleter is never used).
> >
> > 3) Handler.install/uninstall method usages (see setHandler() usages in
> > MultiTaskListener) produces lots of odd cycles where we have only field
> > reassignment. Sure we need at least one TaskListener here.
> >
> > So, I've found that fix for
> > https://bugs.openjdk.java.net/browse/JDK-8187950 is very dirty in point
> > view of compiler performance. And I don't understand what's the purpose
> > of class2Flip map introduction. Could you clarify, help me, please?
> >
> > Cheers,
> > Dmitrii Batkovich
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.openjdk.java.net/pipermail/compiler-dev/attachments/20181113/54270109/attachment.html>