[K42-discussion] Thread object destructor

[Donour Sizemore]

Bryan S Rosenburg wrote:
>
>
> Donour Sizemore wrote on 07/15/2006 05:01:40 PM:
> > Does anybody know why adding a destructor to the base thread object
> > (Thread) would cause the things to overrun the stack fence? 
> According to
> > strategically placed err_printf's, the destructor is never actually
> > getting called.
>
> The base Thread class has no virtual methods, so adding a virtual 
> destructor causes the class to have a vtable pointer where it didn't 
> before.  The "attachment" field may then no longer be the very first 
> word of the structure. 
Oh. Duh, I should have seen that. thanks.

> Code in the Linux module that we import into K42 requires that the 
> attachment field be the first word.  This requirement is documented 
> (but unfortunately not enforced) in lib/libc/scheduler/Thread.H.  I'm 
> guessing that your stack overflow is a consequence of violating this 
> assumption.  Do you really need a virtual destructor in class Thread?
No actually I don't. ThreadMigratable needs one, but I added it to 
Thread by mistake.

donour