Clipper Performance and simultaneous access 1

[ezibecchi]

Hi Guys!

Sorry to bother you with this question but it is really annoying and I have no idea what to do.
The situation is simple: If I access a dbf - for a report for example - and I have that same file

open in another terminal, the performace is 10 times (minimun) slower.

Tech Specs : Clipper 5.2e and Blinker 4.10. Using BLINKER INCREMENTAL OFF and Linking CT.LIB

Test : Windows 2000 Server and 2 WinXP Workstations.

If I run a report from one ot the Workstations, it takes 40 seconds to complete, but if I have

open for share one of the DBFs involving the report in the other workstation..... the report time

goes to 450 seconds!!!!!!!!!!

I have tried different machines, different servers but the difference is the same. I assume that it has to do with how Windows opens the files...

Any help would be great

Thanks
Esteban

 

[GriffMG]

Hello,

I think this is to do with our old favorite 'opportunistic record locking'.

It's a way for Windows on a 4Ghz server with 5 GB or RAM to achieve the same performance as a Netware box on an old 386 with a whole 16MB of RAM!

SO LONG AS THERE IS JUST THE ONE USER! - winge out of the way, you can turn it off.

For the workstations:

REGEDIT4

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkStation\Parameters]
"EnableOplockForceClose"=dword:00000001
"EnableOplocks"=dword:00000000
"UseOpportunisticLocking"=dword:00000000

For the Server:

REGEDIT4

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters]
"EnableOplockForceClose"=dword:00000001
"EnableOplocks"=dword:00000000

If you save the above snippets to files with extensions .reg
you will be able to double click on them and update the registry on the workstations and servers.

I might be slightly different with XP - if so, let me know.

Martin

Regards

Griff
Keep [Smile]ing

 

[ezibecchi]

Thanks Griff for your reply! It gave a lot of info. I found new information from your explanation

Explanation of Opportunistic Logic :

http://support.microsoft.com/kb/129202/en-us

How to disable it in XP (it is slightly different) :

http://itdomino.saleslogix.com/act....25?OpenDocument&ExpandSection=3,2,4#_Section3

I have also found a lot of programs that asks you to disable it!

Now I have a doubt before I test it : As I am not very good at English, I did not fully understand something you just said about "ONE USER". I intend to access the same file from many computers at the same time. Do you think it could lead to some problems with data?. Technically would be many workstations writing to it (lock first!) and many reading it at the same time


Thanks again for your time and your reply. I will let you know as soon as I got all the tests run.


Thanks
Esteban

 

[GriffMG]

No, that shouldn't be a problem - it's one of the things Clipper is designed for.

Martin

Regards

Griff
Keep [Smile]ing

 

[ezibecchi]

Bad news......... I run the tests and when I cancel the OptLock feature of Win2000 what happens is that always takes then longest time to end the processing.

That OptLock feature enhances the reading of a dbf file, except if the file is being already used by another process.......

Too bad, because it is 10 times faster!

Do you have any idea how to enhance it?

See you

 

[GriffMG]

Ezibecchi,

The reference to 'one user' was a mild criticism of MS and that the Opp' File Locking features were meant to make early versions of Lan Manager and Windows Servers look faster than they really were.

There is one other aspect, less well documented, that can cripple the file performance in a multi-user environment.

If a Windows server spots that the first person to open a given file in shared mode is the files 'owner' (generally the user who created it) - it will sometimes do the Opp' locking trick EVEN IF IT IS SWITCHED OFF!

To get around this, get another user to copy the files down to a local drive and then remove the originals from the server - then copy them back logged in as Administrator.

This SHOULD change ownership to the Administrator and everyone should get a fair shot at access!

HTH


Regards

Griff
Keep [Smile]ing