Do database calls to MS/SQL via ODBC block?

[PhotonDemon]

Hi All,

Can anyone tell me if database calls to MS/SQL via ODBC block other forks?

Lou

[waynej]

Blocking would be terrible for our application. See references to AllCallsThreaded, and also implementors of #allCallsThreaded*.

[PhotonDemon]

Hi Wayne,

It seems the default is that the database calls are not threaded and therefor do block. From your note:

Blocking would be terrible for our application. See references to AllCallsThreaded, and also implementors of #allCallsThreaded*.

it seems that you change the default so all database calls are threaded. Is this the case and can you tell me if there is anything I should know before I try this myself?

Thanks, Lou

[waynej]

Right, we change the preference such that we thread database calls, so a database call can run concurrently with other things including other database calls.

It works fine, but it may open your application to concurrency problems you will have to think about. We did it so long ago, I forget what other hurdles you may face.

[PhotonDemon]

Hi Wayne,

Thanks for the info. One more question. I assume that with the database calls set to be threaded, that the fork that calls the database will block for the duration of the call but that other forks will continue?

If this is the case, my code should be fine. I don't make more than one database call from more than one fork at the same time. But having forks that don't make database calls be able to run will be nice.

Lou

[waynej]

Right, Lou.

[marten]

Hi Wayne,

Thanks for the info. One more question. I assume that with the database calls set to be threaded, that the fork that calls the database will block for the duration of the call but that other forks will continue?

If this is the case, my code should be fine. I don't make more than one database call from more than one fork at the same time. But having forks that don't make database calls be able to run will be nice.

Lou

They use static future calls (the external call is always done by the same external native thread) - because some databases MUST be called from the SAME thread (they started the connection with ...) every time - or have other limitations.