From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Zelphir Kaltstahl Newsgroups: gmane.lisp.guile.user Subject: Re: map-par slower than map Date: Thu, 10 Nov 2022 10:52:58 +0000 Message-ID: <8a9b470f-44a4-ac85-c0d1-955724390235@posteo.de> References: <5608809c-89a2-118c-5c05-c46ac3a0e21b@posteo.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="15199"; mail-complaints-to="usenet@ciao.gmane.io" Cc: guile-user To: Damien Mattei Original-X-From: guile-user-bounces+guile-user=m.gmane-mx.org@gnu.org Thu Nov 10 11:53:57 2022 Return-path: Envelope-to: guile-user@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1ot5C0-0003eg-Fa for guile-user@m.gmane-mx.org; Thu, 10 Nov 2022 11:53:56 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ot5BJ-0001HH-KW; Thu, 10 Nov 2022 05:53:13 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ot5BH-0001H7-IW for guile-user@gnu.org; Thu, 10 Nov 2022 05:53:11 -0500 Original-Received: from mout01.posteo.de ([185.67.36.65]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ot5BC-00081s-OX for guile-user@gnu.org; Thu, 10 Nov 2022 05:53:11 -0500 Original-Received: from submission (posteo.de [185.67.36.169]) by mout01.posteo.de (Postfix) with ESMTPS id EEC57240026 for ; Thu, 10 Nov 2022 11:53:00 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.de; s=2017; t=1668077583; bh=9173qZYwYbzDnmwLPE8J3DDOClJAM2M3cbrP7MWs3Tk=; h=Date:Subject:To:Cc:From:From; b=mZyM84Cd4FkVx4J7BklJAtvGk3dvyrAG6UNeWMboQ5UdfdwhdLtQrraPi4b4dY+WG BGI+bwutSnaWmeqE4fy4u/SgVXRQNwG7wHTKxeYYnOSSNqGo5JtcAIqitRF7C2AlYL T6xmzXriRsP8CxVBy5g0tHk0A9+Nl7ZJaosOqv/tZeOTdn6RuLl4Umz5dtmrxp1X+r RbXGTtkwabn6OSnaz3omHbfnPfnBBtnIeZT1Kk2vvcYC6cNqIDpNYm0D3W834AEaEG vFaboBsN37gr4pKCrQH48/zf5c7Dpx0XN2q3cKuRWG0T+06XCE6LmU6L25NTVn2E8N kh8RGD9QsU04w== Original-Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4N7JZz0HCpz9rxR; Thu, 10 Nov 2022 11:52:58 +0100 (CET) Content-Language: en-US In-Reply-To: Received-SPF: pass client-ip=185.67.36.65; envelope-from=zelphirkaltstahl@posteo.de; helo=mout01.posteo.de X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: guile-user@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Guile related discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guile-user-bounces+guile-user=m.gmane-mx.org@gnu.org Original-Sender: guile-user-bounces+guile-user=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.lisp.guile.user:18713 Archived-At: Hi Damien! I think Racket futures and Guile futures are a bit different. According to the Racket documentation "The level of parallelism available from those constructs, however, is limited by several factors, and the current implementation is best suited to numerical tasks." (https://docs.racket-lang.org/guide/parallelism.html#%28part._effective-futures%29). So I am not sure, if they will work well for your use-case. I think I remember there having been a discussion on the Guile mailing list, where I asked, whether the Guile futures suffer from the same limitations, but I am not sure, that this question was sufficiently answered. I personally haven't noticed any blocking in my pure mathematical project Euler code. That said. If you can send me some example code, which does not require me to set up the whole thing of Scheme+, then I can take a look and check on my end, how what when blocks. Or at least send me some snippet, which I can run without setting up lots of things, maybe with 1 simple command, where the entry point to `run-in-parallel` is obvious. Regards, Zelphir On 11/10/22 11:41, Damien Mattei wrote: > note that it is not a Guile problem, the same code give also no speed up with > Racket 'future ,i have not already test it but it should block also on 'touch > future... > > On Thu, Nov 10, 2022 at 11:32 AM Damien Mattei wrote: > > Hello Zelphir, > > i finally find a possible cause of no speed up of my code, i find that > using your code the procedure keep blocked on the first 'touch at line 27 > here: > > https://notabug.org/ZelphirKaltstahl/guile-project-euler-solutions/src/ebb19b11b465903105924adb6252f1e2ecf63859/lib/parallelism.scm#L27 > > if i add a 'display i got this output, see the second part ,i cut it > waiting the rest of output , it is blockers on the first 'touch until it > return ,after all the touch are fast as if all the job is done in the > first 'touch > > unct-unify-minterms-set-1-unit-future : begin > set1-length = 930 > set2-length = 1270 > before Cartesian product set > after Cartesian product set > minterms-set-length = 1181100 > minterms-set-first = ((1 1 1 x x 0 0 0 0 1) (1 1 1 1 x x 0 0 0 1)) > segmts = ((0 . 196850) (196851 . 393701) (393702 . 590552) (590553 . > 787403) (787404 . 984254) (984255 . 1181099)) > before // > run-in-parallel : making future > run-in-parallel : making future > run-in-parallel : making future > run-in-parallel : making future > run-in-parallel : making future > run-in-parallel : making future > run-in-parallel : touching future > run-in-parallel : touching future > run-in-parallel : touching future > run-in-parallel : touching future > run-in-parallel : touching future > run-in-parallel : touching future > after // > unified-minterms-vector-1-length = 1181100 > > funct-unify-minterms-set-1-unit-future : end > funct-unify-minterms-set-1-unit-future : begin > set1-length = 1270 > set2-length = 888 > before Cartesian product set > after Cartesian product set > minterms-set-length = 1127760 > minterms-set-first = ((1 1 1 1 x x 0 0 0 1) (1 1 1 1 1 x x 0 0 1)) > segmts = ((0 . 187960) (187961 . 375921) (375922 . 563882) (563883 . > 751843) (751844 . 939804) (939805 . 1127759)) > before // > run-in-parallel : making future > run-in-parallel : making future > run-in-parallel : making future > run-in-parallel : making future > run-in-parallel : making future > run-in-parallel : making future > run-in-parallel : touching future > > blocking just above > > i find no explanation in Guile doc: > > Scheme Procedure: *touch* /f/ > > Return the result of the expression embedded in future f. > > If the result was already computed in parallel, |touch| returns > instantaneously. Otherwise, it waits for the computation to complete, > if it already started, or initiates it. In the former case, the > calling thread may process other futures in the meantime. > > perheaps 'map is not the good way to "launch" futures? > > here is my version of code with display that genrate the output above: > > (define run-in-parallel >   (λ (segments map-proc) ;;reduce-proc reduce-init) >     "Use futures to run a procedure in parallel, if > multiple cores are available. Take a list of SEGMENTS as > input, which are ranges of values to work on. MAP-PROC is > applied to the SEGMENTS using map. When the MAP-PROC calls > for all segments finished and returned values, the > REDUCE-PROC is applied to the map result using reduce and > the REDUCE-INIT argument." >     (let ([futures >   (map (λ (seg) >  (display-nl "run-in-parallel : making future") >  (make-future >   ;; Need to wrap in a thunk, to not >   ;; immediately start evaluating. >   (λ () (map-proc seg)))) > segments)]) >       ;;(let ([segment-results (map touch futures)]) >       (let ([segment-results (map (lambda (f) >    (display-nl "run-in-parallel : touching future") >    (touch f)) >  futures)]) > segment-results > ;; (reduce reduce-proc > ;; reduce-init > ;; segment-results) > )))) > > > Best regards, > > Damien > > On Wed, Oct 12, 2022 at 11:29 PM Zelphir Kaltstahl > wrote: > > Hi! > > On 10/12/22 22:27, Damien Mattei wrote: > > > https://github.com/damien-mattei/library-FunctProg/blob/master/guile/logiki%2B.scm#L1674 > > > > i commited the current version of code here with all files but it is > > huge.... :-/ > > > > On Wed, Oct 12, 2022 at 10:20 PM Damien Mattei > > wrote: > > > >> Mutex? i do not think code has situation where dead lock could > happen, it > >> is a code about minimalising logic expressions, it uses minterms , > minterms > >> set is a set of minterms :like this: > >> > >> example: > >> ((1 1 0) (1 1 1)) will be unified : (1 1 x) > >> because 0 and 1 are replaced by x > >> the minterms-set could have thousands of pair (mathematic not lisp) > >> minterms to unify > >> if there is more than one x as result there is no need to continue so i > >> escape with a continuation: > >> > >> minterms-set = > >> { > >> ((1 0 1 0) (1 1 1 0)) > >> ((1 0 1 0) (1 1 0 1)) > >> ((1 0 1 0) (1 0 1 1)) > >> ((1 0 1 0) (0 1 1 1)) > >> ((0 1 1 0) (1 1 1 0)) > >> ((0 1 1 0) (1 1 0 1)) > >> ((0 1 1 0) (1 0 1 1)) > >> ((0 1 1 0) (0 1 1 1)) > >> ((0 1 0 1) (1 1 1 0)) > >> ((0 1 0 1) (1 1 0 1)) > >> ((0 1 0 1) (1 0 1 1)) > >> ((0 1 0 1) (0 1 1 1)) > >> ((0 0 1 1) (1 1 1 0)) > >> ((0 0 1 1) (1 1 0 1)) > >> ((0 0 1 1) (1 0 1 1)) > >> ((0 0 1 1) (0 1 1 1)) > >> } > >> > >> replace { } by () to have the list, other example at another level : > >> > >> minterms-set = > >> { > >> ((0 x 1 1) (x 1 1 1)) > >> ((0 x 1 1) (1 x 1 1)) > >> ((0 x 1 1) (1 1 x 1)) > >> ((0 x 1 1) (1 1 1 x)) > >> ((x 0 1 1) (x 1 1 1)) > >> ((x 0 1 1) (1 x 1 1)) > >> ((x 0 1 1) (1 1 x 1)) > >> ((x 0 1 1) (1 1 1 x)) > >> ((0 1 x 1) (x 1 1 1)) > >> ((0 1 x 1) (1 x 1 1)) > >> ((0 1 x 1) (1 1 x 1)) > >> ((0 1 x 1) (1 1 1 x)) > >> ((x 1 0 1) (x 1 1 1)) > >> ((x 1 0 1) (1 x 1 1)) > >> ((x 1 0 1) (1 1 x 1)) > >> ((x 1 0 1) (1 1 1 x)) > >> ((0 1 1 x) (x 1 1 1)) > >> ((0 1 1 x) (1 x 1 1)) > >> ((0 1 1 x) (1 1 x 1)) > >> ((0 1 1 x) (1 1 1 x)) > >> ((x 1 1 0) (x 1 1 1)) > >> ((x 1 1 0) (1 x 1 1)) > >> ((x 1 1 0) (1 1 x 1)) > >> ((x 1 1 0) (1 1 1 x)) > >> ((1 0 1 x) (x 1 1 1)) > >> ((1 0 1 x) (1 x 1 1)) > >> ((1 0 1 x) (1 1 x 1)) > >> ((1 0 1 x) (1 1 1 x)) > >> ((1 x 1 0) (x 1 1 1)) > >> ((1 x 1 0) (1 x 1 1)) > >> ((1 x 1 0) (1 1 x 1)) > >> ((1 x 1 0) (1 1 1 x)) > >> } > >> > >> here we see some minterms are already unified > >> > >>   it is not easy to read even by me because i wrote the code many > years ago > >> and is split in many files, but here it is: > >> > >> (par-map function-unify-minterms-list minterms-set) > >> > >> {function-unify-minterms-list <+ (λ (L) (apply > >> function-unify-two-minterms-and-tag L))} > >> > >> (define (unify-two-minterms mt1 mt2) > >>    (function-map-with-escaping-by-kontinuation2 > >>  (macro-function-compare-2-bits-with-continuation) mt1 mt2)) > >> > >> ;; (function-map-with-escaping-by-kontinuation2 > >> (macro-function-compare-2-bits-with-continuation)   '(1 1 0 1 0 1 1 > 0) '(1 > >> 1 0 1 1 1 1 1)) > >> > >> ;; list1 = (1 1 0 1 0 1 1 0) > >> ;; more-lists = ((1 1 0 1 1 1 1 1)) > >> ;; lists = ((1 1 0 1 0 1 1 0) (1 1 0 1 1 1 1 1)) > >> ;; clozure = # > >> > >> ;; #f > >> ;; > >> ;; (function-map-with-escaping-by-kontinuation2 > >> (macro-function-compare-2-bits-with-continuation)    '(1 1 0 1 0 1 > 1 0) '(1 > >> 1 0 1 1 1 1 0)) > >> > >> ;; list1 = (1 1 0 1 0 1 1 0) > >> ;; more-lists = ((1 1 0 1 1 1 1 0)) > >> ;; lists = ((1 1 0 1 0 1 1 0) (1 1 0 1 1 1 1 0)) > >> ;; clozure = # > >> > >> ;; '(1 1 0 1 x 1 1 0) > >> (define (function-map-with-escaping-by-kontinuation2 clozure list1 . > >> more-lists) > >>    (call/cc (lambda (kontinuation) > >>      (let ((lists (cons list1 more-lists)) > >>    (funct-continu ;; this function have the kontinuation in his > environment > >>     (lambda (arg1 . more-args) > >>       (let ((args (cons arg1 more-args))) > >> (apply clozure kontinuation args))))) ;; a tester: (apply clozure (cons > >> conti args)) > >> > >>           ;; (newline) > >>           ;; (dv list1) > >>           ;; (dv more-lists) > >>           ;; (dv lists) > >>   ;; (dv clozure) > >>           ;; (newline) > >> > >>        (apply map funct-continu lists))))) > >> > >> (define-syntax macro-function-compare-2-bits-with-continuation ;; > >> continuation version of macro-compare-2-bits > >>    ;; i need a macro because of external function to the clozure > >>    (syntax-rules () > >>      ((_) (let ((cnt 0)) ;; counter > >>    (lambda (continuation b1 b2) (if (equal? b1 b2) > >>   b1 > >>   (begin > >>     (set! cnt (add1 cnt)) ;; we leave with continuation in case cpt > > 1, we > >> can have used a flag too instead of a counter > >>     (when (> cnt 1) (continuation #f)) ;; escaping with the > continuation > >>     'x))))))) ;; return x in case of (b1,b2) = (O,1) or (1,0) > >> > >> what could have caused mutex if in the latter definition above (let > ((cnt > >> 0)) ;; counter was defined at top level and shared by all > threads!!! yes > >> there could have be some mutex  but this is not the case, i think > even all > >> function are pure so why is it more slow with // than without? > >> Damien > >> > >> On Wed, Oct 12, 2022 at 8:45 PM Maxime Devos > >> wrote: > >> > >>> On 12-10-2022 19:19, Damien Mattei wrote: > >>>> Hello, > >>>> all is in the title, i test on a approximately 30000 element list , i > >>> got > >>>> 9s with map and 3min 30s with par-map on exactly the same piece of > >>> code!? > >>>   > [...] > >>>   > > >>>> translated from Scheme+ to Scheme: > >>>> (define unified-minterms-set-1 (map function-unify-minterms-list > >>>> minterms-set)) ;;(par-map function-unify-minterms-list minterms-set)) > >>> The definition of 'function-unify-minterms-list' and 'minterms-set' is > >>> missing.  Without a test case, we can only speculate what's going on. > >>> (E.g., maybe it grabs a mutex). > >>> > >>> Greetings, > >>> Maxime. > I don't want to scare anyone, just maybe warn about parallel map. I > once tried > to use Guile's parallel map function for a decision tree implementation > (https://notabug.org/ZelphirKaltstahl/guile-ml/src/cf666801fea91c9fa8fa290764ff6c60b7f3949d/decision-tree.scm), > > where each branch while learning the tree would call parallel map > again for sub > branches and so on. Somehow it made Guile crash (I don't have the > error message > any longer, but I did post about it on the mailing list back then.). I > never > figured out, what went wrong. All I had was pure function calls and > math inside > the thing that parallel map was supposed to run. > > Ultimately I simply tried other parallelism constructs and when I > switched to > using futures instead, everything worked fine, no crashes, no errors. > > Since that time, I did not use parallel map and instead used futures. > Recently I > made a parallelization thing for solving exercises of Project Euler using > multiple cores, so that some solutions are calculated faster. Maybe > this can > help or can be adapted to another use case: > > https://notabug.org/ZelphirKaltstahl/guile-project-euler-solutions/src/ebb19b11b465903105924adb6252f1e2ecf63859/lib/parallelism.scm#L11-L30 > > It expects ranges of things, which are called `segments` in the code. > Usually > ranges of numbers for Project Euler things. Here is the code to split > a range > into segments: > > https://notabug.org/ZelphirKaltstahl/guile-project-euler-solutions/src/ebb19b11b465903105924adb6252f1e2ecf63859/lib/segment.scm > > (Check any solution using it for an example.) > > So this might be a bit too specific for general parallel things, but I > guess one > could change the way futures are used in `run-in-parallel`, to fit any > other > purpose. > > Best regards, > Zelphir > > -- > repositories: https://notabug.org/ZelphirKaltstahl > -- repositories:https://notabug.org/ZelphirKaltstahl