On 4/27/06, Willy Tarreau <[email protected]> wrote:
> On Thu, Apr 27, 2006 at 06:10:07PM +0300, Denis Vlasenko wrote:
> > On Tuesday 25 April 2006 20:53, Avi Kivity wrote:
> > > Very often one needs to acquire a resource, do something with it, and
> > > then free the resource. Here, "resource" can mean a file descriptor, a
> > > reference into a reference counted object, or, in our case, a spinlock.
> > > And we want "free" to mean "free no matter what", e.g. on a normal path
> > > or an exception path.
> >
> > ...
> >
> > > Additionally, C++ guarantees that if an exception is thrown after
> > > spin_lock() is called, then the spin_unlock() will also be called.
> > > That's an interesting mechanism by itself.
> >
> > Life gets even more interesting when you hit another exception
> > inside destructor(s) being executed due to first one.
> > Say, spin_unlock() discovers that lock is already unlocked
> > and does "throw BUG_double_unlock".
> >
> > Even if you
> > (a) remember what standard says about it
> > (b) implemented nested exception handling correctly,
> > then you are still left with
> > (c) let's pray gcc has no bugs in stack unwinding
> > and nested exceptions and nested destructor calls.
> >
> > Mozilla crashes over such things. For Mozilla, crash is not
> > *that* catastrophic. For OS kernel, it is.
>
> Mozilla is written in C++ ? I start to better understand where the
> 160 MB bloat comes from...
Evolution is written in C.
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