[erlang-questions] : Subtle behaviour of Erlang scheduler

Bjorn Gustavsson <>
Tue May 29 11:55:10 CEST 2007


KatolaZ <> writes:
> 
> Well, maybe it does not matter for telecom apps, maybe it does not
> matter for 90% of Erlang code, maybe it is a so rarely used feature,
> but ERLANG HAS A BUGGY SCHEDULER, EVEN IF YOU DON'T WANT TO ADMIT IT. 

Using capitals letters doesn't make your statement more true.
Rather it seems that you are shouting.

That the scheduler does not have all the features you think you'll need
does not mean that it is buggy.

If we just had unlimited time, people and money, we would fix everything
that every single user demanded so that Erlang could be used for every
possible application. The reality is that we must base our developement
on priorities and first work on features that will benefit the majority
of the users.

In this case, the behaviour of the code loader is unfortunate, but it is
extremely easy to work around once you know about it. Trying to fix the
issue in OTP by giving the code server higher priority is not as trivial
as it might seem. We would have to make sure that the change would not
break existing applications. Also, the code server in turn calls other
processes to actually load the code from the disk, so those processes
would have to have their priorities raised too. All this means that there
is a risk of breaking old applications if you make a careless "fix" to
the problem.

Regarding the suggested new features, such as priority propagation or
more priority levels, those are new FEATURES that could be considered for
a future release. Obviously, they would have been to been weighted against
other new features.

/Bjorn
-- 
Björn Gustavsson, Erlang/OTP, Ericsson AB




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