[erlang-questions] hybrid heap question

Kenneth Lundin <>
Wed Feb 28 13:25:18 CET 2007


Hi,

>From our view (OTP team at Ericsson) the Hybrid heap version of the
emulator is experimental. With expreimental I mean that:
 - it is definately
not as stable and well tested as the mature separate heap solution.
- it is not used in any products as far as I know.
- The hybrid heap can be a very good solution when it is finished. The lack of
compiler support (identifying data that will be sent in a message and
can be put on shared heap from the beginning) and the lack of
incremental GC makes it less useful in real products. There will for
example be very long GC's in the current system, which interrupts all
other execution in the VM.
- We have no immediate plans to make Hybrid heap and SMP work together
for several reasons. 1) The separate heap and SMP works very very well
and  we see no problems with using that for any type of application.
2) We are dependent on the competence from the HiPE group in Uppsala
University regarding the Hybrid heap ,we will happily include their
contribution if
they make Hybrid heap work together with SMP , add incremental GC etc.

In summary: Today the separate heap (default) solution is the stable
and recommended one for both SMP and non SMP cases.
Hybrid heap is experimental from our point of view. Might be very
stable on non SMP but that is nothing we guarantee.

/Regards Kenneth (OTP team at Ericsson)

On 2/23/07, Yariv Sadan <> wrote:
> Are there any plans to support both?
>
> Yariv
>
>
> On 2/23/07, Ulf Wiger (TN/EAB) <> wrote:
> >
> > Hybrid is currently not supported in combination
> > with SMP. I hope that will change eventually.
> >
> > BR,
> > Ulf W
> >
> > > -----Original Message-----
> > > From: 
> > > [mailto:] On Behalf Of Yariv Sadan
> > > Sent: den 22 februari 2007 17:46
> > > To: Erlang Questions
> > > Subject: [erlang-questions] hybrid heap question
> > >
> > > Hi,
> > >
> > > Is there any reason not to use 'erl -hybrid'? Also, has
> > > anyone measured the performance difference it gives to some
> > > application that relies on message passing?
> > >
> > > Side note: I suspect that using a hybrid heap would improve
> > > the performance of applications that use the MySQL and/or
> > > Postgres drivers as the database queries and result sets
> > > wouldn't have to be copied when sent between processes. What
> > > do you think?
> > >
> > > Thanks,
> > > Yariv
> > > _______________________________________________
> > > erlang-questions mailing list
> > > 
> > > http://www.erlang.org/mailman/listinfo/erlang-questions
> > >
> >
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