[erlang-patches] Re: gen:call({global, Name}, ...)

[Ulf Wiger]

Hi Geoff,

I agree. Safe_whereis_name/1 doesn't really protect against anything. It does, perhaps reduce the window of some unwanted events, but it doesn't eliminate them.

We did some interesting tests with QuickCheck PULSE on a predecessor of Gproc. Basically, with true concurrency, and even more so in a distributed setting, these sorts of races are not possible to eliminate - at least not without exorbitant costs.

For this reason, gproc:where/1 simply does an ets:lookup(), even in the global case.

BR,
Ulf W

On 31 Mar 2011, at 20:16, Geoff Cant wrote:

> To my mind, this doesn't seem to add much safety. The whereis_name/1
> operation is a single ets:lookup, and ets guarantees us that this read
> is atomic, so the result of the lookup can't be affected by operations
> that require the global lock anyway.

Ulf Wiger, CTO, Erlang Solutions, Ltd.
http://erlang-solutions.com