Merge of nickrob-async-20060513 to mainline?

[Nick Roberts]

 > > Also it still uses pthreads.  You said previously that it should be done
 > > in one process and, following a remark from Jim Ingham, that ptrace is
 > > non-blocking.  AFAICS the problem is that wait *is* blocking and I can't
 > > see of a way to deal with that without using another thread.
 > 
 > I've stated before that I think that making gdb multi-threaded is a
 > seriously bad idea.

I don't know enough about threads to argue a case for them, but I'd like to
note that:

1) Daniel thinks that he can get the same functionality (on GNU/Linux at least)
   without using them.

2) Apple's GDB is multi-threaded and this doesn't seem to cause them problems.

3) It would only be multi-threaded, at most, for the specific platforms that
   asynchronous behaviour was implemented and only when invoked that way.  It
   could even be added as a compile option.

4) GDB appears to already to be a threaded application (at least, for me, it
   uses the libthread_db library).


-- 
Nick                                           http://www.inet.net.nz/~nickrob