Re: multithreaded EH is still broken on Linux/Alpha and other platforms

[Jason Merrill <jason at cygnus dot com>]

>>>>> H J Lu <hjl@lucon.org> writes:

 >>  > The bug is in /omniORB-980827. Here is the patch. I don't know why
 >>  > static omni_thread::init_t omni_thread_init;
 >>  > is in the header file.
 >> 
 >> So that anything that #includes the header is guaranteed that the
 >> thread stuff will have been initialized.  This is a common C++ idiom; it's
 >> even used by many iostream implementaitons.

 > Well, it depends on what omni_thread_init does. I don't think that
 > particular omni_thread_init is designed for having more than one
 > copies or in any random files.

It sure looks to me like that's what it's designed for.  That line is the
canonical form for the idiom I'm talking about.

 >>  > It seems ok for compiler to generate
 >>  > static omni_thread::init_t omni_thread_init;
 >>  > for each source file which includes that header file.
 >> 
 >> I don't understand you.  Your patch just moves the line from the header
 >> into the .cc files, which is unmaintainable.  Why is it useful?

 > Well, that particular .cc file I moved omni_thread_init into will
 > be linked in by every program which uses omni_thread.

 > If you take a closer look at the files I moved omni_thread_init into,
 > and try it on both Linux/x86 and Linux/alpha, you may understand it.

Oh, I see; you just moved it into the various thread port files.  That
makes more sense, but subverts the intent of the original code; it relies
on extra-linguistic means of assuring that the thread package gets
initialized first.

 > Strangely enough, egcs 1.1 only generates one copy of omni_thread_init
 > on Linux/x86 and it happens to be for that particular .cc file where I
 > moved omni_thread_init into. However, on Linux/alpha, omni_thread_init
 > is generated for every .cc file where the header file defining
 > omni_thread_init is included. That is one reason why it works on x86.
 > I think it may be an egcs bug. But I don't have the time to dig into.

That's OK, but please don't call it a fix when it is in fact a workaround.

Jason