Re: [Crash-utility] crash-7.3.2 very long list iteration progressively increasing memory usage
On Tue, 2018-06-26 at 11:27 -0400, Dave Anderson wrote:
----- Original Message -----
> On Tue, 2018-06-26 at 15:34 +0100, Jeremy Harris wrote:
> > On 06/26/2018 03:29 PM, David Wysochanski wrote:
> > > On Tue, 2018-06-26 at 09:21 -0400, Dave Anderson wrote:
> > > > Yes, by default all list entries encountered are put in the built-in
> > > > hash queue, specifically for the purpose of determining whether
there
> > > > are duplicate entries. So if it's still running, it hasn't
found any.
> > > >
> > > > To avoid the use of the hashing feature, try entering "set hash
off"
> > > > before kicking off the command. But of course if it finds any, it
> > > > will loop forever.
> > > >
> > >
> > > Ah ok yeah I forgot about the built-in list loop detection!
> >
> > For a storage-less method of list loop-detection: run two walkers
> > down the list, advancing two versus one elements. If you ever
> > match the same element location after starting, you have a loop.
>
> I agree some algorithm [1] without a hash table may be better
> especially for larger lists.
I'll await your patch...
Do you see any advantage to keeping the hash table for loop detection
or would you accept a patch that removes it completely in favor of a
another algorithm?