[Bug translator/2056] avoid locking within foreach iteration for maps & pmaps

[hunt at redhat dot com]

------- Additional Comments From hunt at redhat dot com  2006-01-05 06:08 -------
(In reply to comment #3)

> Regarding the pmap deadlock, one possible fix is to have foreach() iterating
> over a pmap hold an exclusive lock around the whole loop, and the @extraction
> operators to hold none, when they're nested within foreach().  In fact, ordinary
> array reads enclosed within foreach() don't need to be locked either.  Let's
> transmute this bugzilla entry to track this bug.

Maybe I'm missing something, but the problem is the writelock.  Why does the
generated code take a writelock on the pmap when it is reading stats?

I suspect the reason is confusion over reading from a map and a pmap.  You need
a writelock when doing _stp_pmap_agg() or _stp_pmap_get().  However,
_stp_pmap_agg() creates a normal map and you only want to readlock it when reading.

Until this gets fixed, pmaps of stats are broken because we cannot print without
using foreach.


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http://sourceware.org/bugzilla/show_bug.cgi?id=2056

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