Hallo,
When I caught an exception in methode Execute and re-raise it
in a synchronised TThreadMethode, the RTL tries to free the
Exception-Objekt twice. Does anybody have some tip what's wrong
with my code? Thanks in advance.
procedure TWorkerThread.Execute;
[..]
if Assigned(FJobObj) and (not Terminated) then
begin
FJobObj.FThread := Self;
try
try
FJobObj.Execute;
raise Exception.Create('TestTest');
except
on E: Exception do
begin
if Assigned(FJobObj) and (not Terminated) then
begin
FJobObj.FLastException := E;
SyncResult;
end;
end;
end;
finally
{ Following conditions return false, }
{ and Execute is exited (FreeOnTerminate = TRUE) }
if Assigned(FJobObj) and (not Terminated) then
SyncResult;
if Terminated then
FreeAndNil(FJobObj);
end;
end;
[..]
procedure TWorkerThread.SyncResult;
begin
if Assigned(FJobObj.FOnResult) then
Synchronize(TriggerResult);
end;
procedure TWorkerThread.TriggerResult;
begin
FJobObj.FOnResult(FJobObj, FJobObj.FLastException);
end;
procedure TForm1.JobResults(AJobObj: TJobObject; E: Exception);
begin
try
{ Now the developer is a fool and he re-raises the Exception, }
{ causes the RTL to free the exception object twice, see trace }
{ below. If I create and throw a new exception there won't be a }
{ problem. }
if E <> nil then
raise E;
finally
{ Needs to be freed here! Since the destruktor will nil }
{ object variabel "FJobObj" of the thread, important! }
AJobObj.Free;
end;
end;
--------------------------------2008/4/1
14:20:46--------------------------------
FastMM has detected an attempt to call a virtual method on a freed object.
An access violation will now be raised in order to abort the current
operation.
Freed object class: Exception
Virtual method: Destroy
Virtual method address: 403830
The allocation number was: 505
Stack trace of when the object was allocated (return addresses):
402D58 [EMAIL PROTECTED]
4037E7 [system.pas][System][TObject.NewInstance][8360]
403B6A [EMAIL PROTECTED]
4105EA [sysutils.pas][SysUtils][Exception.Create][13251]
463AD8 [Pooltest1.pas][Pooltest1][TMyJob.Execute][50]
462E91 [ThreadPool.pas][ThreadPool][TWorkerThread.Execute][344]
7C91E21F [ZwQueryVirtualMemory]
7C80B9BD [VirtualQueryEx]
7C80B9E6 [VirtualQuery]
Stack trace of when the object was subsequently freed (return addresses):
402D83 [EMAIL PROTECTED]
403805 [system.pas][System][TObject.FreeInstance][8366]
403BB5 [EMAIL PROTECTED]
40383E [system.pas][System][TObject.Destroy][8379]
40384B [system.pas][System][TObject.Free][8385]
403FBC [EMAIL PROTECTED]
7C9137BF [RtlConvertUlongToLargeInteger]
7C91378B [RtlConvertUlongToLargeInteger]
7C947B48 [RtlUnwind]
The current stack trace leading to this error (return addresses):
40384B [system.pas][System][TObject.Free][8385]
40405F [EMAIL PROTECTED]
420690 [classes.pas][Classes][TThread.Synchronize][9599]
7C9137BF [RtlConvertUlongToLargeInteger]
7C91378B [RtlConvertUlongToLargeInteger]
7C947860 [LdrAddRefDll]
7C9137BF [RtlConvertUlongToLargeInteger]
7C91EAFA [KiUserExceptionDispatcher]
7C812A5B [RaiseException]
--
Arno Garrels
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