Re: [Caml-list] Thread behaviour

[Tom Ridge <tom.j.ridge+caml@googlemail.com>]

On 30 September 2013 10:18, Xavier Leroy <Xavier.Leroy@inria.fr> wrote:
> On 2013-09-27 12:10, Tom Ridge wrote:
>> I have a little program which creates a thread, and then sits in a loop:
>> [...]
>> When I run the program I get the output:
>>
>> 1
>> 2
>>
>> and the program then sits in the loop.
>
> On my machine (OCaml 4.01.0, Ubuntu 12.04 LTS), I sometimes see what
> you see, and sometimes I see the expected output:
>
> 1
> 2
> 3
> hello
> 4
>
> It all depends on the whim of the OS scheduler.  OCaml has no control
> over it.  And you shoudn't expect any kind of fairness from the OS
> scheduler, esp. Linux's, which gladly jettisons any pretense of
> fairness in the hope of getting better throughput.
>

Ah! You are saying that the problem (maybe) lies with the Linux scheduler.
This had never occurred to me. Probably because I assumed the Linux
phrase "completely fair scheduler" meant something (although
admittedly, I never tried to find out what).

Thanks