[Jprogramming] Performance Issues!

[Henry Rich]

I don't think I changed anything in @: or [: .  But I did make lots of 
changes in memory management, and especially in counting the allocated 
space.  I'll look into it.

Henry Rich

On 8/8/2016 2:32 PM, Jose Mario Quintana wrote:
> Apparently, the performance of @: vs [: has taken a turn for
> the worse under the beta-10 engine.
>
> One the one hand, this discussion should have been in the Beta forum.  On
> the other hand, general performance of programs is entertained; so, it
> might belong here as well (alright, alright, I am having difficulty logging
> in to my mail associated to the beta forum, my apologies).
>
> I was surprised when I was checking out some performance comparison in the
> JWithATwist thread in the Chat forum. First, I noticed that there were a
> straw-man verb comparisons of between [: and @ (as opposed to @:). I guess
> that is unfortunately unavoidable because, apparently, most
> J programmers use @ by default.  In addition, it was not taken
> into consideration that forks naturally associate to the right whereas
> conjunctions naturally associate to the left.
>
> However, the under performance of @: vs [: persisted after addressing these
> omissions and an alarm went off in my head!
>
> First a comparison running J4:
>
>     JVERSION
> Engine: j804/j64/windows
> Release: commercial/2015-12-21 16:18:48
> Library: 8.04.15
> Qt IDE: 1.4.10/5.4.2
> Platform: Win 64
> Installer: J804 install
> InstallPath: j:/program files/j
> Contact: www.jsoftware.com
>
>     stp=. ([ ((<;._1 '|Sentence|Space|Time|Space * Time') , (, */&.:>@:(1
> 2&{))@:(] ; 7!:2@:] ; 6!:2)&>) (10{a.) -.&a:@:(<;._2@,~) ]) ".@:('0 : 0'"_)
>
>
>     stp 1
> ([: - [: - [: - [: - ])      i. 10000000
> (- @: (- @: (- @: (- @: ]))))i. 10000000
> ([: ([: ([: ([: - -) -) -) ])i. 10000000
> (- @: - @: - @: - @: ])      i. 10000000
> (- @  - @  - @  - @  ])      i. 10000000
> )
> ┌────────────────────────────────────────┬─────────┬────────┬────────────┐
> │Sentence                                │Space    │Time    │Space * Time│
> ├────────────────────────────────────────┼─────────┼────────┼────────────┤
> │([: - [: - [: - [: - ])      i. 10000000│402656512│0.178322│7.18024e7   │
> ├────────────────────────────────────────┼─────────┼────────┼────────────┤
> │(- @: (- @: (- @: (- @: ]))))i. 10000000│402657024│0.178733│7.1968e7    │
> ├────────────────────────────────────────┼─────────┼────────┼────────────┤
> │([: ([: ([: ([: - -) -) -) ])i. 10000000│671092864│0.185165│1.24263e8   │
> ├────────────────────────────────────────┼─────────┼────────┼────────────┤
> │(- @: - @: - @: - @: ])      i. 10000000│671092352│0.176141│1.18207e8   │
> ├────────────────────────────────────────┼─────────┼────────┼────────────┤
> │(- @  - @  - @  - @  ])      i. 10000000│268439936│5.73629 │1.53985e9   │
> └────────────────────────────────────────┴─────────┴────────┴────────────┘
>
> The sentences are performing as I expected in both terms, space and time.
> The corresponding versions of [: and @: have the same performance whereas @
> uses less than half of the space but has a (relative) pretty bad time
> performance.
> Now the same comparison running J5 (the one I was originally using):
>
>     JVERSION
> Engine: j805/j64/windows
> Beta-10: commercial/2016-08-01T13:13:21
> Library: 8.04.15
> Qt IDE: 1.4.10/5.4.2
> Platform: Win 64
> Installer: J804 install
> InstallPath: j:/program files/j
> Contact: www.jsoftware.com
>
>     stp=. ([ ((<;._1 '|Sentence|Space|Time|Space * Time') , (, */&.:>@:(1
> 2&{))@:(] ; 7!:2@:] ; 6!:2)&>) (10{a.) -.&a:@:(<;._2@,~) ]) ".@:('0 : 0'"_)
>
>
>     stp 1
> ([: - [: - [: - [: - ])      i. 10000000
> (- @: (- @: (- @: (- @: ]))))i. 10000000
> ([: ([: ([: ([: - -) -) -) ])i. 10000000
> (- @: - @: - @: - @: ])      i. 10000000
> (- @  - @  - @  - @  ])      i. 10000000
> )
> ┌────────────────────────────────────────┬─────────┬────────┬────────────┐
> │Sentence                                │Space    │Time    │Space * Time│
> ├────────────────────────────────────────┼─────────┼────────┼────────────┤
> │([: - [: - [: - [: - ])      i. 10000000│402656000│0.22633 │9.1133e7    │
> ├────────────────────────────────────────┼─────────┼────────┼────────────┤
> │(- @: (- @: (- @: (- @: ]))))i. 10000000│671091840│0.168359│1.12985e8   │
> ├────────────────────────────────────────┼─────────┼────────┼────────────┤
> │([: ([: ([: ([: - -) -) -) ])i. 10000000│671091840│0.177579│1.19172e8   │
> ├────────────────────────────────────────┼─────────┼────────┼────────────┤
> │(- @: - @: - @: - @: ])      i. 10000000│671091840│0.191088│1.28238e8   │
> ├────────────────────────────────────────┼─────────┼────────┼────────────┤
> │(- @  - @  - @  - @  ])      i. 10000000│268439296│1.34543 │3.61167e8   │
> └────────────────────────────────────────┴─────────┴────────┴────────────┘
>
> One difference is the much improved time performance of @; that is the good
> news.  The other difference is the one related to the second sentence; the
> space use cannot longer match the one of the first sentence.
>
> Needless to say that if this latter issue implies under performance under
> certain broad conditions and it persists in J5 after the beta then it will
> be a huge disappointment for programmers (such as yours truly) who avoid [:
> like the plague.
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