At 12:32 PM 29/03/2003 +0530, you wrote:

>Hi,
>
>I face a strange problem.
>Sometimes Firebird server crashes with an access violation.
>(This happens under Windows 98 as well Windows 2000)
>I am using FB Server 1.0 Build 794.
>
>It is something that I am doing in my code which is causing this problem.
>
>It is replicable at my end if certain conditions are met.
>There are four sections of code interacting which causes the condition to
>be met.
>
>I am including the four sections
>
>In section one I am creating a connection to the database.
>After that now under 98 if i click on fbserver icon on the tray I can see
>the number of attachments.
>Firebird properties page now show number of attachments is 1
>
>Section one
> try
> If Not IB_Connection1.Connected then
> IB_Connection1.Connect;
> except
> on e:EIB_ISCError do
> HandleAllErrs(self,e);
> on e:Exception do
> Raise;
> ENd;
>------------------------------------------------------------------------------------------------------
>
>
>Section two is first creating a transaction.
>
>Section two
>
>TranMain is a global variable
>
>if not Assigned(TranMain) then
> TranMain:=TIBOTransaction.Create(self);
>TranMain.IB_Connection := IB_Connection1;
>
>TranMain.ExecuteImmediate('update tblconfiguration set NUSERS = ' +
>InttoStr(NumUsers) + ' , NTASKS=0, NMESSAGES=0');
>
>TranMain.CommitRetaining ;
>TranMain.refresh(false);
>----------------------------------------------------
>
>Section three is used to retrieve some information.
>
>Section 2
>
>var
> Rs:TIBOQuery;
>
>begin
> Rs:=nil;
>Try
> Rs:=TIBOQuery.Create(self);
> Rs.IB_Connection := IB_Connection1;
> rs.SQL.Add('select DBVersion,PersonaldbVersion from tbldbconfig');
> rs.Prepare;
> Rs.Open;
> if rs.RecordCount>0 then
> begin
> <do something with info from rs>
> end;
>finally
> rs.Close;
> if assigned(rs) then freeandnil(rs);
>
>end;
>end;
>------------------------------------------------------------------------------
>I expect that section 2 and section 3 code should not increase the number
>of attachments as shown on the firebird properties page.
>This is true only Sometimes .
>in most of the time the line
>
>TranMain.ExecuteImmediate('update tblconfiguration set NUSERS = ' +
>InttoStr(NumUsers) + ' , NTASKS=0, NMESSAGES=0');
>
>or the line
>
>Rs.Open;
>
>causes the number of attachments to increase (+1 each).
>
>Not able to identify when. I am just going through the debugger. No change
>in the code but sometimes attachments will show 1, sometimes it will show
>morethan that
>
>
>If the number of attachments are morethan one then a line from Section 4
>will cause Firebird server to give a gp fault and shut down
>
>Section 4
>Var
> IBDB:TIBDatabase;
> DbInfo:TIBDatabaseInfo;
> SParams:Tstrings;
> DbSize:int64;
>begin
>Try
>Try
> IBDB:=nil;
> DbInfo:=nil;
> DbSize:=0;
> IBDB:=TIBDatabase.Create(nil);
> SParams:=TStringList.Create;
> SParams.Add('user_name=sysdba');
> SParams.Add('password=masterkey');
> with IBDB Do
> Begin
> DatabaseName :=RServerIP + ':' +
> IncludeTrailingPathDelimiter(RDBPath) + RDBName;
> Params:=SParams;
> AllowStreamedConnected:=false;
> LoginPrompt:=false;
> Open ;
> End;
>
> DbInfo := TIBDatabaseInfo.Create(nil);
> DbInfo.Database := IBDb;
>
> try
> CurrentNoOFDBCxns := DbInfo.UserNames.Count-1;
> Except on e:exception Do
> Application.terminate;
> End;
>Except
> On E:EIBInterBaseError Do // 336331022
> raise EIBInterbaseError.Create(e.SQLCode,e.IBErrorCode,'['+
> inttostr(e.IBErrorCode) + ']' + e.Message);
> on E:Exception Do
> Raise Exception.Create(e.Message);
>End;
>Finally
>Begin
> if Assigned(IBDB) then
> Begin
> if IBDB.Connected then
> IBDB.Connected:=false;
> freeandnil(IBDB);
> End;
> if Assigned(DbInfo) then
> FreeandNil(DbInfo);
> If Assigned(sPArams) then
> FreeAndnil(sparams);
>End;
>End;
>end;
>--------------------------------------------------------------
>The exact line which will cause Firebird Server to crash is the following line
>
>CurrentNoOFDBCxns := DbInfo.UserNames.Count-1;
>
>Any help much appreciated.
>
>Helen,
>Can is cross post this in ib-support

No, it's a problem with your application, not a database problem. If you
post in ib-support I will move you back here.

My initial observation of your code is that it is an unholy jumble of
native IBO, TDataset-compatible IBO and IBXpress. IOW, your AVs are coming
from your Delphi application - most likely from the utter confusion of
connections and transactions you have there....and that's only in the code
we can actually *see*.

Not sure why you need to drag in an IBDatabase in Section 4 (which will
certainly give you a new connection each time you create it); but in that
block of code you have three try.. keywords + one except and one finally,
i.e. you have one improperly finished try block.

Also in that section you are referencing two objects before they have been
created.
IBDB:=nil;
DbInfo:=nil;
Both would cause an AV but the first one will crash the program before the
second one gets a chance to do it.

This looks weird too:
CurrentNoOFDBCxns := DbInfo.UserNames.Count-1;

In any case, you can get the *correct* count without resorting to
IBX. Once you get your data access objects sorted out (using TIBODatabase
instead of TIB_Connection, you only have to read the Users property (a
TStrings) to count the usernames logged in...

That's not all, actually. The transactions are a dog's dinner...

Helen