MIT develops new tool that can interrupt infinite loops
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MIT develops new tool that can interrupt infinite loops
1–10 of 72 posts
Re: MIT develops new tool that can interrupt infinite loops
#2Seems to me like this sort of thing could be pretty good for advanced users who understand it's limitations and potential failure modes, but a nightmare waiting to happen for everyone else.
And of course I'm also inclined to suggest that advanced users would be better off attaching gdb to the process to get done what they need to, then coredumping and contacting the developer...
Re: MIT develops new tool that can interrupt infinite loops
#3First of all the solution of this problem is computationally impossible so this tool makes me feel realy uneasy I'd never use it -- it would actually make predictable easily reproducible bugs impossible to report when this tool is activated. It makes an assumption that infinite loops are just stuck with a false condition and nothing else is affected by that, which I believe is fundametally false.
Re: MIT develops new tool that can interrupt infinite loops
#4I thought the message at the end about people expecting full correctness was a bit off; after all, if we expected fully-correct programs, we would be proving them instead of writing C.
Re: MIT develops new tool that can interrupt infinite loops
#5Can't think of a use-case for this? .... maybe if you have some seriously "legacy" process running somewhere that loves to stall but patching is not an option for some obscure reason? ... space probes?
Re: MIT develops new tool that can interrupt infinite loops
#6The RunStop key?
Re: MIT develops new tool that can interrupt infinite loops
#7First of all the solution of this problem is computationally impossible so this tool makes me feel realy uneasy I'd never use it -- it would actually make predictable easily reproducible bugs impossible to report when this tool is activated. It makes an assumption that infinite loops are just stuck with a false condition and nothing else is affected by that, which I believe is fundametally false.
It appears to take memory snapshots. If it detects a repeat in the snapshots it knows that the program will loop indefinitely. Of course it can't detect all infinite loops, but a sizeable subset.
Re: MIT develops new tool that can interrupt infinite loops
#8Not even a single mention of the halting problem?
Re: MIT develops new tool that can interrupt infinite loops
#9I've done this with MS Word and the VS debugger. Word crashed while I was editing a huge document. I simply skipped a few instructions down, returned to Word, saved the document, and restarted Word. When your options are either 1) crash, or 2) possibly recover to some working state, it's pretty easy to choose option 2.
Re: MIT develops new tool that can interrupt infinite loops
#10First of all the solution of this problem is computationally impossible so this tool makes me feel realy uneasy I'd never use it -- it would actually make predictable easily reproducible bugs impossible to report when this tool is activated. It makes an assumption that infinite loops are just stuck with a false condition and nothing else is affected by that, which I believe is fundametally false.
It appears to take memory snapshots. If it detects a repeat in the snapshots it knows that the program will loop indefinitely. Of course it can't detect all infinite loops, but a sizeable subset.
In theory I believe it can actually detect all infinite loops, for an extremely generous definition of "can detect". On a finite-memory machine, a computation fails to halt iff it eventually repeats a state, which it must do in finite time, since there are only finitely many possible states (the finite-ness is what makes the halting problem not apply). However, that finite time might be extremely large, perhaps longer than the age of the universe. A http://en.wikipedia.org/wiki/Busy_beaver function gives an upper bound on how long it can be.
But yeah, the practical use is to tell you when a computation is already looping, for the large subset of infinite loops that result in states being repeated relatively quickly.