[freetds] FreeTDS on Core 2 Duo problem
Medvidek Pu
Pu.Medvidek at seznam.cz
Fri Feb 16 08:37:51 EST 2007
Hi all,
I've just come accross a strange behavior of FreeTDS running on Core 2 Duo CPU. I'm using it from PHP. The pages with sql queries were generated much faster on my older machine than on my brand new Core 2 Duo PC. I've done a little investigation and I found that queries take an unreasonable amount of time. Looking more closely into the matter I found the following strange behavior:
1. I've created a script sql-test with the following content:
<code>
#!/bin/sh
for ((i=1; i<100; i++)); do sqsh -U sa -S my_server -D my_db -P my_passwd -i my_query.sql -p; done
</code>
It runs the same query repeatedly (100 times) and prints some statistcs (how much time it took).
2. While running the sql-test script above, the time a single query takes grows and grows. Sometimes it drops to reasonable time (0.1s) but then it grows upto several seconds.
3. But, running the sql-test script on two consoles concurrently, makes each single query complete in reasonable time. As the two sql-test processes take different time, one of them stops earlier then the other. After one of the two sql-test processes stops, the queries from the other sql-test process immediately start to run much slower.
4. Moreover, when I run the sql-test script while a PHP page with sql queries is being generated, then the PHP page is generated fast. When I do *not* run the sql-test script while a PHP page is being generated, then the PHP page is generated slowly.
5. When I generate two PHP pages with sql queries simultaneously, the pages are generated fast.
Summary: It is clearly not PHP-related thing, because the problem appears even in SQSH alone. It is clearly also not a SQSH-related thing, because PHP-SQSH is fast and PHP-PHP is fast. Therefore, I think it is a FreeTDS-related problem.
Is it a bug in FreeTDS? Is it a misconfiguration? Any ideas, solutions?
Thanks
Pavel
FreeTDS 0.64 and 0.63
SQSH 2.1.4
OpenSuSE Linux 10.2 x86
CPU: Core 2 Duo @ 2.4
RAM: 2GB
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