Fixing memory leaks with FastMM4

[Alberto Paganini 3]

I have started removing memory leaks in my application and installed and configured FastMM4. 

I ran the application and the following is an excerpt from the memory leaks report.

--------------------------------2020/6/20 21:24:00--------------------------------
A memory block has been leaked. The size is: 100

This block was allocated by thread 0x13C4, and the stack trace (return addresses) at the time was:
404DA6 [System.pas][System][@GetMem$qqri][3454]
406E0F [System.pas][System][TObject.NewInstance$qqrv][13000]
40747E [System.pas][System][@ClassCreate$qqrpvzc][14164]
45926E [System.Classes.pas][System.Classes][Classes.TStringList.$bctr$qqrv][6408]
EAF697 [uBetFairAPIHorseHelperBL.pas][uBetFairAPIHorseHelperBL][TBetFairAPIHorseHelperBL.ResetEventID$qqrv][921]
EAED20 [uBetFairAPIHorseHelperBL.pas][uBetFairAPIHorseHelperBL][TBetFairAPIHorseHelperBL.ListEvents$qqr20System.UnicodeString][611]
D4C0EB [DBAccess][TCustomDADataSet.GetRecordCount$qqrv]
E92D6A [uTokenBL.pas][uTokenBL][TTokenBL.GetTokenID$qqrv][34]
E5A73D [Main.pas][Main][TMainForm.btnFindRacesClick$qqrp14System.TObject][190]
E5B5C5 [Main.pas][Main][TMainForm.FormActivate$qqrp14System.TObject][418]
557E7D [Vcl.Forms][Forms.TCustomForm.Activate$qqrv]

The block is currently used for an object of class: System.Classes.TStringList

The allocation number is: 199660

Current memory dump of 256 bytes starting at pointer address 7F322C00:
2C A7 44 00 00 00 00 00 00 00 00 00 40 B7 A9 7F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 01 00 00 00 88 40 34 7F 01 00 00 00 04 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FF FC CD 79
80 80 80 80 80 80 80 80 00 00 00 00 01 33 32 7F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
99 E6 0B 00 A6 4D 40 00 0F 6E 40 00 7E 74 40 00 6E 92 45 00 18 6E 40 00 7E 74 40 00 2D 37 D7 00
CA 53 D7 00 A3 11 DA 00 93 E9 D3 00 A8 4F D4 00 C4 13 00 00 C4 13 00 00 C2 4D 40 00 2D 6E 40 00
C9 74 40 00 23 8B 45 00 73 6E 40 00 8E 37 D7 00 73 6E 40 00 67 54 D7 00 ED 11 DA 00 73 6E 40 00
EB 37 CD 00 5C 00 00 00 2C A7 44 00 26 3A 59 8A 94 A2 F1 00 80 80 80 80 80 80 80 80 80 80 80 80
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As this is the first time I use FastMM4 I don't know how to start to fix the leaks.

Can somebody point out a tutorial that starts from scratch on this topic?

 

Many thanks

Alberto

[Alexander Sviridenkov 356]

Looks like TStringList is created in TBetFairAPIHorseHelperBL.ResetEventID and never destroyed.

[Alberto Paganini 3]

26 minutes ago, Alexander Sviridenkov said:

Looks like TStringList is created in TBetFairAPIHorseHelperBL.ResetEventID and never destroyed.

Thank you very much for your answer, Alexander. Is there anything on the web that teaches how to read the report?

[Alexander Sviridenkov 356]

Report is quite simple. First part is call stack, Usually top items are from RTL and gives you little info, so skip items from top until you'll find your own unit, this will be class/method where leaked block was created,

Second section is (possible) class that uses this block.