Re: [Crash-utility] crash-7.3.2 very long list iteration progressively increasing memory usage

On 06/26/2018 10:40 AM, David Wysochanski wrote: > 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? Could the same algorithm be modified so that it can slow down after a certain number of list members, say maybe saving only every 10th element to the hash (but checking every new one)?