[#CORE-2018] Only one client can access a readonly database

Firebird Core

Only one client can access a readonly database

Created: 28/Jul/08 12:59 PM Updated: 08/Nov/09 07:13 PM

Component/s:

Engine

Affects Version/s:

2.1.0, 2.1.1

Fix Version/s:

2.5 Beta 1

Time Tracking:

Not Specified

Environment:

Windows XP SP3, own Delphi application created with IBObjects

Planning Status:

Unspecified

Description

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Multiple access to a READONLY database (dialect 3, ODS > 10.) is not possible -> application hang-up.
Readonly is set by a batch using gfix.exe -mode read_only. Same problem exists with classic and superserver 2.1.0 and 2.1.1.
Using the same application with firebird 2.0.3 or 2.5 beta it works.
What can be the problem?

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Dmitry Yemanov added a comment - 30/Jul/08 05:03 AM

Are you sure it works with v2.0.3 Classic?

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Guido Maucher added a comment - 30/Jul/08 06:03 AM

I just tried it again: v2.0.3 Classic is fine.

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Vlad Khorsun added a comment - 14/Oct/08 06:10 AM

When new attachment\transaction started, engine creates lock using this att\tx's ID as a key. This new IDs derives from numbers stored on header page. For readonly databases this numbers incremented but never written back to the header page. Thus SS worked ok while two different processes of CS got the same numbers and then wait in lock manager indefinitely.

Solution is to introduce common database-wide counter in shared memory. All processes of CS is able to assign att\tx ID's using this common counter and don't conflict with each other.

Such counter is implemented using existing lock manager facilities.