On Fri, 4 May 2001, Chris Stith wrote:
> My suggestion is to let libraries that are threadsafe (system
> libraries as well as Perl moduels would be nice) be used as such
> so the advantages of that can be realized, while at the same time
> defaulting to serialized calls for libraries which are not, so
> your threaded programs which need to call nonreentrant functions
> can do so with some level of safety.
I still don't buy it. Consider a non-thread-safe getpwnam(), and
serialized access from two threads:
Thread | Operation
1 | struct passwd *ent = getpwnam("valid");
2 | struct passwd *ent = getpwnam("invalid");
1 | printf("home: %s\n", ent->pw_dir); /* boom; ent is NULL */
So to make the Perl code C<$id = getpwnam()> safe, I think perl would not
only have to serialize calls, but copy the data from the static pointer
into thread-local storage.
Should perl be given this overhead on all platforms just for the benefit
of those with non-thread-safe libcs? Probably not; it should probably
call a reentrant interface if available. But the reentrant interfaces are
all different. Hence the foam frothing from Jarkko's mouth.
Cheers,
-Ben
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signer: can't create ~/.sig: Wrong medium type
