Submitted by: @pavel-zotov

Attachments:
memory-leak-when-use-show-grants-in-FB_301-or-FB_400.7z
firebird.conf.files.7z

1) Run ProcessExplorer or similar tool for monitoring process resources

2) create empty database, add it to databases.conf (aliases.conf for 2.5)

3) Run following .sql script several times:

set wng off;
set list on;
set echo on;

connect 'localhost:e25' user sysdba password 'masterke';
show grants;
quit;

Sample of batch for this ('fbc' variable stored path to different FB binaries on the same host ):

@echo off
set fbc=C:\MIX\firebird\fb25sS\bin
::set fbc=C:\MIX\firebird\fb25\bin
::set fbc=C:\MIX\firebird\fb30
::set fbc=C:\MIX\firebird\fb30sC
::set fbc=C:\MIX\firebird\fb40
::set fbc=C:\MIX\firebird\fb40sc

for /l %%i in (1,1,10) do (
echo %%i
%fbc%\isql -q -i memotrouble.sql 1>memotrouble.log 2>&1
)

On WI-T4.0.0.267 and WI-V3.0.1.32542 you will find noticable memory leak for FB process (I've tested bothSS and SC).
No such trouble on WI-V2.5.6.27017 SC or SS.

Please see screenshots in attached .7z file.

Commits: a8fdbdf ee105dd

====== Test Details ======

No way to detect memory leak using FB monitoring; it seems that Python 'psutil' package could help but it's not supplied in standard Python kit.