Sounds like the _tempnam() function could be a lot smarter in creating
temporary filenames. Is that our function or is it provided by Windows?
Wade.
On Fri, 23 Jan 2015 20:13:17 +1100, Sergey Logichev <[email protected]>
wrote:
Jafar,
I am very appreciate for your investigations! Actually, my Windows %TMP%
folder included ~135000 temporary files, so when I cleaned it my run
>time decreased from ~40 secs to ~20. And the very first open() was
instant, then its time increased as number of temporary files increases
too. My >proposal to purge all temporary files after program finishes or
instead use virtual storage at RAM, as on every searched subdirectory is
created single >temporary file. After very short time TMP folder will
contain a myriad of such files.
Nevertheless I confirm that number of threads practically do not
influence on execution time. Probably, it's the problem of "lazy
cleanup", as you >mentioned. Hope you could find solution. Compared with
Linux - Windows is quite a bag of different bugs! Which runs from every
holes :-)
Thank you,
Sergey
23.01.2015, 10:19, "Jafar Al-Gharaibeh" <[email protected]>:
Sergey,
Thanks for the report. I had in mind to look at why we don't get much
speed up with more threads. I did look and found that the main >>thread
was grabbing most "new thread tokens" and not recycling them fast
enough. I have to tweak my algorithm to allow quick >>cleanup and reuse
of threads. I will do that when I get a chance.
Now the second issue - and you've gotta love this!-, I was able to
confirm the slow open(). With the help of gdb and after spending a
>>couple of hours digging into the C code and the Windows API calls, I
found that the problem is in a call to _tempnam() to create a
>>temporary file name. The call was taking so long to finish. It
creates the tmp file under your system TMP folder (%TMP% on >>Windows).
I looked in that folder and found that it has more than half a million
files (~2.7GB)!It turned out that every time my program runs, Windows
was looping through that huge pile of tmp files to find a name that
doesn't >>exist so that it can give it to the program. Of course I
think most of those tmp files were generated by my program during
previous runs >>the last couple of days. As a bonus, I discovered a
memory leak in the process of tracking the open() problem. I committed
a fix for that leak. This is only >>affecting Windows.
Short term solution: flush your TMP folder.
Long term: we will into ways to improve our tmp file strategy to
overcome the shortcoming of Windows API. This will come in a later
>>date! :)
Cheers,
Jafar
On Thu, Jan 22, 2015 at 4:43 AM, Sergey Logichev <[email protected]>
wrote:
Jafar,
You've provided very interesting version of walk directory algorithm.
Communication with active threads' is a great thing!
I have checked your program under Windows 7. I was confused the fact
that execution time is negligibly depended on number of >>>concurrent
threads. I dug into and discovered that the first operation open(s)
takes near ALL execution time! 95% at least. Check it >>>yourself when
you slightly edit getdirs():
...
if ( stat(s).mode ? ="d" ) & ( tm := &time, d := open(s) ) then {
if n=1 then write(s," : ",&time-tm)
...
So, if first open() is so long then all other enhancements have no
sense. Please clarify if I am wrong.
Best regards,
Sergey
22.01.2015, 00:58, "Jafar Al-Gharaibeh" <[email protected]>:
Here is a slightly tweaked/reformatted version. It now by default
auto-detect the number of available cores in the >>>>machine and
launch twice as many threads.
--Jafar
On Wed, Jan 21, 2015 at 12:17 PM, Jafar Al-Gharaibeh
<[email protected]> wrote:
David,
I added a threaded solution @
http://rosettacode.org/wiki/Walk_a_directory/Recursively#Icon_and_Unicon
Please review/edit as you see fit. (The source file is attached).
Combining recursion with thread might not be the >>>>>best solution
for this problem. If I were to put this in real use I'd go with an
iterative approach using master/workers >>>>>model. Anyway, this is
a excellent demonstration on how to use threads!. The key features
are:
1- How to create threads, limit their numbers, self-load balanced
(new threads are spawned at the time/place >>>>>where needed. One
they are done, they vanish allowing new threads to pop up in new
places in the directory >>>>>structure)
2- pass data and collect results to/from the threads using the new
language features.
Here is some sample output from my desktop machine (quad-core with
mechanical HDD. I will try another machine >>>>>with an SSD and see
if more threads scale better).the first argument to the program is
the target directory. The second is the maximum number of
concurrent threads >>>>>to use at any given moment. (soft limit! my
counters are "unmutexed", so the actual number might deviate). Note
>>>>>that this is different from the actual number of threads used
during the run which is reported at the end. The >>>>>program can
create/destroy threads as needed, but cannot use more than "max" #
of threads at any given moment, >>>>>and again "max" is "soft". :)
Cheers,
Jafar
c:\proj>tdir c:\ 1
39708 directories in 99867 ms using 1 threads
c:\proj>tdir c:\ 4
39708 directories in 62222 ms using 4 threads
c:\proj>tdir c:\ 4
39708 directories in 87650 ms using 4 threads
c:\proj>tdir c:\ 1
39708 directories in 92525 ms using 1 threads
c:\proj>tdir c:\ 4
39708 directories in 95655 ms using 4 threads
c:\proj>tdir c:\ 16
39708 directories in 66138 ms using 21 threads
c:\proj>tdir c:\ 8
39708 directories in 69307 ms using 8 threads
c:\proj>tdir c:\ 4
39708 directories in 70539 ms using 4 threads
c:\proj>tdir c:\ 16
39708 directories in 76392 ms using 32 threads
On Sun, Jan 11, 2015 at 1:25 PM, David Gamey
<[email protected]> wrote:
Sergey,
I am responsible for much of the Rosetta code contributions (thanks
also to Steve, Andrew, Matt, Peter, >>>>>>and about 4 others) and
this one in particular dating from 2010. As I recall this was
before the multi->>>>>>threading versions were widely available. I
think multi-threading is underrepresented in Rosetta/Unicon.
If you come up with a multi-threading version, we should add it to
the post as an alternative version. If >>>>>>you don't feel
comfortable doing this, post the code and I can add it.
David
From: Sergey Logichev <[email protected]>
To: Jafar Al-Gharaibeh <[email protected]>Cc: Unicon group
<[email protected]>Sent: Sunday, January 11, 2015
1:16 AM
Subject: Re: [Unicon-group] Walk of file directory
Jafar,
Thank you for a whole bundle of advices and suggestions! Threads
are worth to >>>>>>>try. The thought of search by file attributes
is very useful too. Your suggestion >>>>>>>about slow I/O partly
is right. For UNIX I tried the program on Raspberry Pi with
>>>>>>>6 Class microSD as HDD (it's slow, agree). But for Windows
it was quite fast >>>>>>>HDD. It would be interesting to compare
performance of the program on >>>>>>>Windows with classic approach
based on Win32 _FINDFIRST, _FINDNEXT >>>>>>>functions. I have
threaded Delphi/Lazarus implementations of this algorithm.
>>>>>>>Feel that it will be faster but in which degree?
Sergey
10.01.2015, 21:50, "Jafar Al-Gharaibeh" <[email protected]>:
Sergey,
There are so many things that came to mind when I saw your
>>>>>>>>program.
1- At the end of your email, sourceforge ad says "Go Parallel",
>>>>>>>>Which is not a bad idea for this highly parallel
application.There is a similar program "wordcount" listed in my
dissertation >>>>>>>>(available on unicon.org) that go through
directories and count >>>>>>>>words in every file using threads
(Chapter 7, page 107)
2- Unicon open() already supports " pattern matching that would
>>>>>>>>greatly (I believe) speedup your program. For example you
can do >>>>>>>>this:
L := open("*.icn")
to get a list of all of Unicon source files in the current
directory. Note: It would be nice if there were a way to tell
open() to return files >>>>>>>>not only based on a pattern, but
also on file attribute to allow >>>>>>>>something like "get me
all directories in the current directory", or >>>>>>>>"get me all
read only file". There are a lot of situations where filtering
>>>>>>>>directory names for example is very useful - like this
program
3- The program on Rosetta Code is not optimized for speed. You
>>>>>>>>can minimize the number of lists created and put() by
careful >>>>>>>>rewriting of the code.
4- Depending on how deep the directory tree is, there might be a
lot >>>>>>>>of I/O going on. A slow disk might limit how fast you
can go >>>>>>>>regardless of how optimized your code is.
I will share results if get around trying any of these options.
Cheers,
Jafar
On Sat, Jan 10, 2015 at 5:51 AM, Sergey Logichev
>>>>>>>><[email protected]> wrote:
Hello all!
Now I investigate the best approach to get list of files in
specified >>>>>>>>>directory and beneath in Unicon.
I found excellent example at rosettacode.org:
http://>>>>>>>>>rosettacode.org/wiki/Walk_a_directory/>>>>>>>>>Recursively#Icon_and_Unicon
I reconstructed this one to implement matching of filenames to
>>>>>>>>>specified pattern (regular expression). My program
recursively >>>>>>>>>walks a directory and prints appropriate
filenames. The same as >>>>>>>>>dir (ls) does. All working fine
except performance. If directory has >>>>>>>>>a lot of subdirs
the search may took 10-20 seconds before >>>>>>>>>starting
output. Could you provide some advices how to enchance
>>>>>>>>>the performance?
Some notes how to make and use. Unpack content of udir.zip to
>>>>>>>>>your local directory. Define which environment you use
in env.icn >>>>>>>>>file - uncomment line "$define _UNIX 1" in
the case of UNIX. >>>>>>>>>Nothing to do in the case of Windows.
Make udir program:
unicon -c futils.icn
unicon -c options.icn
unicon -c regexp.icn
unicon udir.icn
Usage: udir -f<filemask>
for example: udir -f*.icn
shall list of icn files in the current dir and all its
subdirectories.
Best regards,
Sergey Logichev
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Media, is your
hub for all things parallel software development, from weekly
thought
leadership blogs to news, videos, case studies, tutorials and
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look and join the conversation now.
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