Re: Re: JDBC Performance - Mailing list pgsql-general
| From | Keith L. Musser |
|---|---|
| Subject | Re: Re: JDBC Performance |
| Date | |
| Msg-id | 008e01c032bd$e6218ca0$0201a8c0@quantum.idisys.com Whole thread Raw |
| Responses |
Re: Re: JDBC Performance
|
| List | pgsql-general |
Gunnar,
Sorry about getting the wrong name. Yes, I was referring to the modifications you posted. I ran a few more tests, which I think will clarify things:
Test #1 Test #2 Test #2 w/ GC
---------- --------- -----------
jdbc7.0-1.2.jar 1.89 ms 5.0 ms 3.9 ms
postgresql.jar (191450 bytes) 1.36 ms 3.1 ms 3.2 ms
postgresql.jar (204223 bytes) 1.78 ms 3.9 ms 4.1 ms
In Test #2 w/ GC, I purposefully ran System.gc() every 150 msec during the test. This reduces my dependence on how often I create and free objects. It also made the original driver faster than the new one.
The times depend significantly on what I do in my program -- if I cache results, I can see execution times slow down significantly (sometimes slower by a factor of 20!). (The numbers above are with the cache turned OFF.) That's why I'm running the GC frequently; with it, I get consistently good times.
The two versions of postgresql.jar are both less sensitive to memory allocation in my part of the program. That is, the times do no grow when I use a cache with these drivers.
I conclude the following:
-----------------------------
(1) the older postgresql.jar is faster than the newer one (the 191450 byte version is older). I don't know what's the difference; I didn't every realize I had two different versions until this morning.
(2) both are faster than jdbc7.0-1.2.jar in most circumstances
(3) use of System.gc() can significantly alter execution times, making benchmarking very difficult.
Hope this helps. I've attached the source for "Test #1". Test #2 is more
complicated, and probably not worth your effort -- it depends so heavily on how System.gc() is called.
- Keith
P.S. My system is RH Linux 6.2, PostgreSQL 6.5.3 on i686-pc-linux-gnu, JVM is JDK1.2.2_006 with green threads.
-----Original Message-----
From: Gunnar R|nning <gunnar@candleweb.no>
To: Keith L. Musser <kmusser@idisys.com>
Cc: PGSQL-General <pgsql-general@postgresql.org>
Date: Monday, October 09, 2000 11:17 PM
Subject: Re: [GENERAL] Re: JDBC Performance
>"Keith L. Musser" <kmusser@idisys.com> writes:From: Gunnar R|nning <gunnar@candleweb.no>
To: Keith L. Musser <kmusser@idisys.com>
Cc: PGSQL-General <pgsql-general@postgresql.org>
Date: Monday, October 09, 2000 11:17 PM
Subject: Re: [GENERAL] Re: JDBC Performance
>
>> I did try out Peter's new JDBC driver on two very simple query-only
>> applications. It was about 15% slower on one of the apps and 10% faster
>> on the other, compared with jdbc7.0-1.2.jar. It worked correctly on
>> both tests.
>>
>> Neither is particularly representative, but the fact that one's faster
>> an one's slower is surprising. I have not had the time to dig into why
>> the discrepancy.
>>
>
>I assume you mean the driver the modifications I posted, unless Peter
>hasn't checked in anything to CVS recently that I am unaware off ? (I'm not
>online with my CVS snapshot at the moment...)
>
>I would sure like to see your applications(or the differences between
>them), so I can take a look at analyzing the discrepancies. Also platform
>information like jdk version, vendor and OS information is interesting. I
>suspect that the optimizations I did can have different effects depending
>on the cost of allocating new objects in a specific environment.
>
>Regards,
>
> Gunnar
>
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