[REBOL] Re: [series] Series performance was Re: MySQL-protocol.r
From: tim:johnsons-web at: 3-Jan-2004 8:15
* Ashley Trüter <[atruter--labyrinth--net--au]> [040102 21:46]:
> Hi Tim,
> > But I believe that lists and blocks are implemented
> > differently internally, but I'm ignorant as to how.
> > any comments on this?
> Conceptually, a block is just a collection of values where the sequence is
> directly known (ie. like an "array" REBOL knows where the Nth value is). A
> list on the other hand ensures that each value knows where the previous
> and next values are (finding the Nth value in this case involves "walking"
> the list one value at a time).
That much I'm aware of. What I didn't know is if blocks are single or
multiple dereferences, and if lists are single or double-linked lists.
Your *very nice* test results gives some clues
My guess is that the lists are double linked, and the block items
are dereferenced just once. (resizable arrays?)
My thought had been that perhaps using a list instead of a block
for mysql-protocol in converting data types might be more
efficient, however, from your test results, it's apparent that
would not be the case.
Whereas 'insert entails resizing the entire block and reallocating
memory, big overhead.
Nice work! Thanks. We should archive this somewhere.
I sure will. :-)
> The following test attempts to highlight the strength and weakness of each
> series! type (keep in mind that the memory cost of list! / hash! is higher
> than block!).
> Test Data
> One million numbers from one through to one million in a 6.75MB file.
> Test Environment
> Intel Pentium 3.0 GHz with 1GB of RAM.
> Operations Per Second
> Operation Block! List! Hash!
> ================== ========= ========= > first / last 1,961,614 2,038,423
> pick / poke / at 1,844,334 504 1,846,456
> find / select (1) 1,546,259 1,538,385 1,399,606
> find / select (2) 52 51 1,402,559
> foreach 13 20 19
> insert 81 1,087,684 19
> insert tail 1,032,956 861,769 723,152
> change 1,572,834 1,569,881 1,307,086
> head / tail / next 1,883,858 1,916,338 1,816,748
> remove 80 1,493,110 54
> remove tail 1,127,093 1,187,992 1,115,157
> (1) First value in series
> (2) Last value in series
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Tim Johnson <[tim--johnsons-web--com]>