Hi Christian:
--- On Sun, 3/29/09, Christian Tismer <[email protected]> wrote:
> here comes a little input from me about deadlock detection.
Thanks for the comments!
> Yes. This is what I would do pretty differently.
> Not using a register method to be called by hand.
> Instead, I would overwrite the definition of channels
> and modify the channel methods to do the deadlock
> detection.
I thought about wrapping the channel operations. The problem with automatic
detection is the system can enter a deadlock before all the resources can be
discovered and diagnostics provided.
global ch1
global ch2
def a():
ch1.send() <-- blocked at time T
ch2.receive() <-- never discovered
def b():
ch2.send() <-- blocked at time T + n, now system is deadlocked
ch1.receive() <-- never discovered
> Would it be possible to do that traversal incrementally, updating
> on every channel action?
Yes this could be done. I would imagine a DeadlockException could be thrown and
it is up to the application in question to figure out what to do. In a system
where there is some notion of process (grouping of tasklets), incremental would
be a better approach - 'kill' the deadlocked group of tasklets. An individual
traversal graph would be smaller too.
> Well, isn't that simple approach sufficient: tracking all actions until >the
> deadlock occours, and that's about it? Maybe I was too quick with >something
> :-)
No, you asked similar questions to what I initially asked myself. Since I am
just starting, I wanted to keep things simple :-).
Cheers,
Andrew
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