ID: 33070
User updated by: lindsay at bitleap dot com
Reported By: lindsay at bitleap dot com
-Status: Bogus
+Status: Open
Bug Type: Performance problem
Operating System: Linux 2.6.10 kernel
PHP Version: 5.0.3
New Comment:
sniper at php dot net:
I'll suggest a faster cpu is not the solution. On the same machine,
the bunzip2 binary decodes the same 4MB bzip'd file in under 2
seconds.
time bunzip2 4M.bz2
real 0m1.198s
user 0m1.162s
sys 0m0.034s
And bzdecompress did it in:
476 seconds or 7 minutes and 56 seconds.
Almost 8 minutes versus 2 seconds on the same machine with the same
data sample would suggest a problem with bzdecompress.
Previous Comments:
------------------------------------------------------------------------
[2005-05-27 09:11:43] [EMAIL PROTECTED]
Get faster machine or use some other compression method than bz2.. (try
your test using the bunzip2 binary and you'll see it's equally slow..)
------------------------------------------------------------------------
[2005-05-23 21:19:02] lindsay at bitleap dot com
I noticed the new code was crashing. You can reliably reproduce the
results by creating a file which compresses well. I created my data
sample with the following commands:
dd if=/dev/zero bs=1024 count=65536 of=large
bzip2 large
When I run the script on this, I get the following crash:
file length 256K ran in: 0 seconds
file length 512K ran in: 1 seconds
file length 1M ran in: 1 seconds
file length 2M ran in: 2 seconds
file length 3M ran in: 2 seconds
file length 4M ran in: 3 seconds
file length large ran in: *** glibc detected *** double free or
corruption (!prev): 0x0853f418 ***
------------------------------------------------------------------------
[2005-05-23 20:09:43] lindsay at bitleap dot com
I applied the patch suggested by jeff at vertexdev dot com. I also
added another test for 64M data chunks. Just to be sure, I verified
php's bzdecompress w/ the patch produces data creating the same md5sum
as bzunzip.
file length 256K ran in: 0 seconds
file length 512K ran in: 0 seconds
file length 1M ran in: 2 seconds
file length 2M ran in: 1 seconds
file length 3M ran in: 3 seconds
file length 4M ran in: 3 seconds
file length 64M ran in: 38 seconds
------------------------------------------------------------------------
[2005-05-23 16:50:02] lindsay at bitleap dot com
It looks like BZ2_bzRead() requires a file to read from. Would:
BZ2_bzDecompressInit
loop BZ2_bzDecompress //decompress in chunks
BZ2_bzDecompressEnd
work?
The source code for BZ2_bzBuffToBuffDecompress seems like it could
almost be used if the BZ2_bzDecompress was looped through 'source' in
chunks.
------------------------------------------------------------------------
[2005-05-23 10:02:56] [EMAIL PROTECTED]
jeff at vertexdev dot com:
Yes. And now look at the code.
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the rest of the comments, please view the bug report online at
http://bugs.php.net/33070
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