[erlang-questions] Ideas for a new Erlang

Richard A. O'Keefe <>
Thu Jun 26 07:32:38 CEST 2008


> I wrote:

> I hope that we can rely on Erlang garbage collection to
>>
>> collect any process suspended in a receive construct and not  
>> registered
>> and not referenced by any other process.  If we can, the  
>> distinction is
>> only useful to people and not really needed by the computer.
>

Perhaps I should make it clear that I was not entirely serious in that
hope.  It *would* be nice, but it was really a stick to beat the  
'channels'
proposal with.  Since channels can be used in the way that processes are
now, and since a reference to a Nystrom channel amounts to a reference  
to
its process, channels have much the same consequences for/problems with
distributed GC as processes.

On 26 Jun 2008, at 4:35 pm, Matthew Reilly wrote:
> This will doubtfully ever happen. Since erlang is distributed, a pid  
> may be referenced via a process on a completely different node, so  
> any garbage collection of pids would therefore need to be distributed.

Distributed GC is no longer rocket wizardry.
(Well, it _is_, but the wizards have published.)

> Adding on to this term_to_binary,  mnesia, ... pids could be stored  
> in different formats or even on disk.

The same, of course, applies to channels.  So when DO channels go away?
>
>
> You also may wish to have pids that are unreferenced by any other,  
> but still do important work e.g.
>
> loop() ->
>   after 1000 ->
>      % Touch the hardware watchdog to prevent the system from  
> reboooting
>      file:read_file("/dev/watchdog"),
>      ?MODULE:loop()
> end

Imprecise wording on my part; I didn't intend waiting for a timeout to  
count,
only waiting for a message.

Interestingly, if you have channels, and a process is waiting for a  
message
on a channel, and no other process has a reference to that channel, the
process is effectively dead, no matter how many other channels it has or
how many other processes have references to them.





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