Re: [boost] Comments about N2320

From: Alexander Terekhov (terekhov_at_[hidden])
Date: 2007-11-02 10:04:09

Anthony Williams wrote:
[...]
> N2420 (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2420.pdf)
> covers some of the relevant ground --- it's the minutes of the POSIX/C++
> liaison committee.

"Gnu gcc and Solaris pthreads: The Gnu gcc and Solaris pthreads 
implementations are two known implementations that attempt to map 
POSIX pthread cancellation onto C++ exception handling, but both 
do so at the cost of breaking the exception model (i.e., they no 
longer conform to ISO C++) because the alternative appears to be 
that C++ destructors and catch blocks would not be invoked for 
cancellation which would mean that resources would be leaked."

Uhmm. Don't know about (modern) Solaris, but glibc (presumably 
that is meant by "Gnu gcc pthreads implementation") does invoke 
C++ destructors and catch blocks. But instead of using ordinary
exceptions, it uses "forced unwinding" for thread cancel and
exit. For some unknown reason (other than "I say it must be 
so"), glibc maintainer Drepper of Red Hat simply refuses to
even contemplate changing it to use ordinary exceptions instead 
of "forced unwinding"... and I suspect that is the reason why 
WG21 was asked to drop standardization of thread cancel (and exit) 
as exceptions.

regards,
alexander.