[Python-ideas] Async API: some code to review

[Cesare Di Mauro]

2012/10/29 Mark Hackett <mark.hackett at metoffice.gov.uk>

> On Monday 29 Oct 2012, Richard Oudkerk wrote:
> > Writing (short messages) to a pipe also
> > has atomic guarantees that can make having multiple writers perfectly
> > reasonable.
> >
> > --
> > Richard
> >
> > _______________________________________________
> > Python-ideas mailing list
> > Python-ideas at python.org
> > http://mail.python.org/mailman/listinfo/python-ideas
> >
>
> Is that actually true? It may be guaranteed on Intel x86 compatibles and
> Linux
> (because of the string operations available in the x86 instruction set),
> but I
> don't thing anything other than an IPC message has a "you can write a
> string
> atomically" guarantee. And I may be misremembering that.
>


x86 and x64 string operations aren't atomic. Only a few, selected,
instructions can be LOCK prefixed (XCHG is the only one that doesn't
require it, since it's always locked) to ensure an atomic RMW memory
operation.

Regards,
Cesare
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