Memory problem

Hanne Berthelsen · Post by **Hanne Berthelsen** » Tue 20 Jun 2006 08:46

I am using MySQL Data Access Component (MyDAC) v. 4.00.1.6 / Borland C++ Builder 5

My application slowly "eats up memory" if regularly accessing a field that does not exist even though there is a try ... catch around accessing the nonexisting field.

try
{
GroupID = MyTable->FieldByName("GroupID")->AsInteger;
}
catch (...)
{
GroupID = 0;
}

Would it help to upgrade to latest version of MyDAC ?

Antaeus · Post by **Antaeus** » Tue 20 Jun 2006 09:50

We couldn't reproduce described problem using the current MyDAC build. Try downloading current version of MyDAC (4.30.1.15) and test the problem once more. If it persists then send us (evgeniyD*crlab*com) please a complete small sample to demonstrate it, including script to create and fill table.

Hanne Berthelsen · Post by **Hanne Berthelsen** » Wed 21 Jun 2006 08:30

I have tried MyDAC v. 4.30.1.15 - problem still exists.

I have sent an example to 'evgeniyD*crlab*com'

Regards Hanne

Antaeus · Post by **Antaeus** » Wed 21 Jun 2006 12:59

We have thoroughly tested this problem. This is memory leak of C++Builder error handling system. It appears when handling exceptions that are raised from functions in dcu made by Delphi. It can be easily reproduced using ADO components instead of MyDAC or by calling

Code: Select all

DatabaseError("Some text");

instead of

Code: Select all

GroupID = MyTable->FieldByName("GroupID")->AsInteger;

Hanne Berthelsen · Post by **Hanne Berthelsen** » Wed 21 Jun 2006 13:15

Does anybody know :
Would it also happen for if upgrading to C++ Builder 6 or Borland Developer Studio 2006?

Antaeus · Post by **Antaeus** » Wed 21 Jun 2006 14:49

We can reproduce this problem in C++Builder 6 but not in Borland Developer Studio 2006. We have tested the solution you have sent us by e-mail. Changing

Code: Select all

catch (...)

to

Code: Select all

catch (Exception &E)

really helps to avoid the memory leak.

Hanne Berthelsen · Post by **Hanne Berthelsen** » Thu 22 Jun 2006 07:00

I have tested during the last 15 hours. No memory has been lost at all.

Exception has been raised more than 125,000,000 times.

So it is the catch (...) for Borland C++ Builder 5/6 that is the problem and should be substituted by catch (Exception &E).