Re: Locks and threads

[Neil Jerram <neil@ossau.uklinux.net>]

Andy Wingo <wingo@pobox.com> writes:

> Hey Neil,
>
> On Thu 12 Mar 2009 01:53, Neil Jerram <neil@ossau.uklinux.net> writes:
>
>> Thanks to a hint from helgrind, I think the problem might be that the
>> symbols obarray is not thread-safe.  But surely using a mutex for
>> every symbol that Guile reads would be terrible for performance...
>
> Dunno, in GStreamer we found that uncontended locks are cheap cheap
> cheap. AFAIU they don't even cause context switches. And the reader will
> be less important in terms of e.g. startup time once the VM lands.

Hi Linas, Andy,

Many thanks for your input on this.  I'll go ahead with a mutex or
rwlock.  First thing is to see if it fixes the problem; if it does,
I'll try to measure the performance impact.

      Neil

PS. And thanks Clinton too - although I'd prefer not to have to do
such a big rewrite if we can manage without it.