Re: [Rlib-devel] [PATCH] Use ZLIB to compress page contents

[Zoltan B. <zb...@du...>]

Hi,

the previous patch needed a little fix.
I replaced c_stream.avail_out with c_stream.total_out
two places after the compressing was done, so the correct
stream size is used. Updated patch is attached.

Also I did a little benchmarking:

Best time out of 5 runs for uncompressed streams:

time for i in `seq 1 1000`; do ./test >test4.pdf ; done

real    0m2.108s
user    0m0.862s
sys     0m1.240s

Best time out of 5 runs for compressed streams:

$ time for i in `seq 1 1000`; do ./test >test3.pdf ; done

real    0m2.475s
user    0m1.073s
sys     0m1.393s

Difference in total time: 367 msec or 17% increase

$ ls -l test3.pdf test4.pdf
-rw-rw-r--  1 zozo zozo 2569 jan 18 12:14 test3.pdf
-rw-rw-r--  1 zozo zozo 3004 jan 18 12:12 test4.pdf

About 14.5% decrease in size.

Here is the results of one of my reports that has a very small recordset.

Uncompressed:

$ time for i in `seq 1 1000`; do ./ptgriport Bolt2 szallitolista 0=20
2005-01-01 2005-12-31 ; done

real    1m3.501s
user    0m32.082s
sys     0m18.655s

Compressed:

$ time for i in `seq 1 1000`; do ./ptgriport Bolt2 szallitolista 0=20
2005-01-01 2005-12-31 ; done

real    1m4.142s
user    0m32.178s
sys     0m18.393s

The performance difference is negligible, 642 msec, about 1% increase.
The database access times dominate here mostly. But look at the file size=
s:

$ ls -l /tmp/szallitolista.pdf*
-rw-rw-r--  1 zozo zozo 1676 jan 18 12:54 /tmp/szallitolista.pdf
-rw-rw-r--  1 zozo zozo 5402 jan 18 12:49=20
/tmp/szallitolista.pdf.uncompressed

With a much larger recordset that produce more than one pages,
or when the pages contain more information, the much larger
decrease in size will justify the time spent in compression
as less data will be written out.

Also if used from PHP through a browser, the smaller file
will be transferred faster. The network is slower than disks.

Best regards,
Zolt=C3=A1n B=C3=B6sz=C3=B6rm=C3=A9nyi