Meyer, OO and concurrency

Bjorn Gustavsson <>
Mon Aug 1 16:04:16 CEST 2005

Alex Arnon <> writes:

> On 01 Aug 2005 14:32:16 +0200, Bjorn Gustavsson <> wrote:
> > "Richard A. O'Keefe" <> writes:
> > > and there are still issues about copying.
> > 
> > Some customer requested that we should make the process dictionary more
> > efficient, and so we did.
> > 
> 1) I understood that the process dictionary is on-heap. So, what
> copying issues are there?

The keys and values are never copied, but there is some internal copying of
cons cells when two or more keys hash to the same hash value. Copying is necessary
to avoid creating references from the oldest generation heap to the youngest.

> 2) How is it implemented? Put another way, what performance impact
> will number of keys have?

2a. It is a hash table. 2b. Not much.


Björn Gustavsson, Erlang/OTP, Ericsson AB

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