[Python-3000] patch: bytes object PyBUF_LOCKDATA read-only and immutable support

[Joel Bender]

> Sounds much like the modes offered by an old operating system that had a 
> very nice lock manager.

Awe, VMS isn't THAT old, is it?  :-)

I have a wrapper around threading.Lock and threading.RLock that I've 
been using that does deadlock detection and have wished for these lock 
modes many times.  I would hesitate to create a PEP to support this 
until I actually new I could pull it off.

I would be happy to share the code that I have with anybody that might 
find it useful, and welcome some help in implementing these modes.

There's one other very useful feature, and that was a callback from the 
lock manager when a lock that you held was blocking a request from some 
other process.


Joel