[#CORE-2498] Make a single attachment usabe by more than one simultaneous threads in embedded

Firebird Core

Make a single attachment usabe by more than one simultaneous threads in embedded

Created: 06/Jun/09 03:17 AM Updated: 12/Nov/09 03:05 PM

Component/s:

None

Affects Version/s:

2.5 Beta 1

Fix Version/s:

2.5 Beta 2

Time Tracking:

Not Specified

Planning Status:

Unspecified

Description

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It was throwing "attachment handle is busy" error. Now callers will block until others requests are completed.

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Alexander Peshkov added a comment - 08/Jun/09 08:50 AM

Adriano, is it tested anyhow / anyway except SAS? I do not see any code problems at the first glance, but agree that we are trying to walk on a very thin ice at beta stage.

Next, I see at least one potential problem with this improvement - it makes possible to have bad programming style. Imagine MT application, which is using single attachment in all threads. With this improvement it will be very hard to notice any problem as long as such application is not running on SMP system under high load. And I can imagine a ticket like 'FB 2.5 badly supports SMP in MT environment'.

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Dmitry Yemanov added a comment - 08/Jun/09 10:59 AM

Alex, I somewhat disagree. Surely we should clearly document that we don't support concurrent access to an attachment, regardless of whether we block or throw an error. As soon as it's documented, everybody stepping on this rake can be reasonably blamed in the support lists or the tracker. I'm not sure we can (or even should try to) protect from whatever stupid application users can code.