Subject Re: [firebird-support] *** possible bug in FB 2.5.2 supperclassic with UDF *** solved
Very glad you solved this problem with my tip =)
Also, there are more pitfalls when building a UDF using Delphi (maybe another languages too). I agree with you that this must be added to Firebird's FAQ, maybe with a link to some document explain all pitfalls.

2013/11/28 ICAMSoft <icamsoft@...>

Thanks for anybody who replied and

again my apology for the easiness i charged firebird for the problem...


The problem's reason and the solution for any who may concern:


As some of repliers said the problem was in memory management of delphi under concurrent threads.

After  15 years using delphi,  i discovered by googling the variable IsMultiThread


Adding in initialization section the following line

IsMultiThread :=true;

everything is ok, also using superclassic (at least in my machine).


PS1: <IsMultiThread :=true> is silently done by Delphi itself, if threads exist in the uses list. Bad for me, my functions where pretty simple and so threads unit was not declared in uses.

PS2:  I think that this could be a major trap for many delphi programmers and that a relative note in documentation about UDF with Delphi in should be added


Best Regards



Athens, Greece