I was interested to see if I could determine what was happening with this. After some playing around, I noticed the code was running significantly faster if I *didn't* compile it, but ran it with 'runghc' instead (running under ghci was also fast).<br>
<br>Here are the running times I found. The 'Zip.hs' program comes with the zip-archive package. The runtime of the compiled version didn't seem to be affected by optimisations. Regardless, I'm quite surprised running interpreted was significantly faster than compiled.<br>
<br>> time runghc ./Zip.hs -l ~/jdk1.6.0_05-src.zip<br> 1.48s user 0.17s system 97% cpu 1.680 total<br><br>> time ./dist/build/Zip/Zip -l ~/jdk1.6.0_05-src.zip <br> 89.00s user 1.06s system 98% cpu 1:31.84 total<br>
<br>The file 'jdk1.6.0_05-src.zip' was just an 18MB zip file I had lying around. I'm using ghc 6.12.1<br><br>Cheers,<br><br clear="all">-- <br>David Powell<br>
<br><br><div class="gmail_quote">On Tue, Aug 10, 2010 at 12:10 PM, Jason Dagit <span dir="ltr"><<a href="mailto:dagit@codersbase.com">dagit@codersbase.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br><br><div class="gmail_quote"><div class="im">On Mon, Aug 9, 2010 at 4:29 PM, Pieter Laeremans <span dir="ltr"><<a href="mailto:pieter@laeremans.org" target="_blank">pieter@laeremans.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Hello,<br><br>I'm trying some haskell scripting. I'm writing a script to print some information <br>from a zip archive. The zip-archive library does look nice but the performance of zip-archive/lazy bytestring <br>
doesn't seem to scale.<br><br>Executing : <br><br> eRelativePath $ head $ zEntries archive <br><br>on an archive of around 12 MB with around 20 files yields <br><br>Stack space overflow: current size 8388608 bytes.<br>
</blockquote><div><br></div></div><div>So it's a stack overflow at about 8 megs. I don't have a strong sense of what is normal, but that seems like a small stack to me. Oh, actually I just check and that is the default stack size :)</div>
<div><br></div><div>I looked at Zip.hs (included as an example). The closest I see to your example is some code for listing the files in the archive. Perhaps you should try the supplied program on your archive and see if it too has a stack overflow.</div>
<div><br></div><div>The line the author uses to list files is:</div><div>List -> mapM_ putStrLn $ filesInArchive archive</div><div><br></div><div>But, you're taking the head of the entries, so I don't see how you'd be holding on to too much data. I just don't see anything wrong with your program. Did you remember to compile with optimizations? Perhaps try the author's way of listing entries and see if performance changes?</div>
<div class="im">
<div><br></div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br><br>The script in question can be found at :<br><br><a href="http://github.com/plaeremans/HaskellSnipplets/blob/master/ZipList.hs" target="_blank">http://github.com/plaeremans/HaskellSnipplets/blob/master/ZipList.hs</a><br clear="all">
<br>I'm using the latest version of haskell platform. Are these libaries not production ready, <br>or am I doing something terribly wrong ? <br></blockquote><div><br></div></div><div>Not production ready would be my assumption. I think an iteratee style might be more appropriate for these sorts of nested streams of potentially large size anyway. I'm skeptical of anything that depends on lazy bytestrings or lazy io. In this case, the performance would appear to be depend on lazy bytestrings.</div>
<div><br></div><div>You might want to experiment with increasing the stack size. Something like this:</div><div>./ZipList +RTS -K100M -RTS foo.zip</div><div><br></div><font color="#888888"><div>Jason</div></font></div>
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