[c++-pthreads] Restating the Jason model

[Wil Evers]

Jason Merrill wrote:

> On Tue, 13 Jan 2004 07:47:17 -0500, Dave Butenhof <David.Butenhof at hp.com> wrote:
 >
>>Cancellation should NOT be disabled in destructors? Did you mean to say
>>that?
> 
> Yes.  Destructors can be run under two different situations: 
> 
>  1) when the object goes out of scope during normal execution; 
>  2) when unwinding the stack during exception handling.
> 
> In #1, an exception thrown out of a destructor is propagated normally.  In
> the #2, it causes a call to terminate().  So we need to suppress
> cancellation for #2, but not (necessarily) #1.

It is true that an exception escaping from a destructor will not trigger 
immediate program termination when the program/thread in question is not 
unwinding; however, that doesn't mean there's nothing to worry about. 
The most likely symptom is a resource leak; in a multi-threaded 
environment, that could mean a deadlock.

- Wil