Using Valgrind and GDB together to fix a segfault and memory leak

[@ricktierney6508]

Thank you for this explanation! You are a great teacher and this helped me fix my memory leak in one hour instead of one week

[@MikeShah]

Cheers!

[@shawnkuo6566]

Seriously, how do you resize the left half screen at 5:54 ?

[@MikeShah]

Check out my tmux tutorial: kzbin.info/www/bejne/bpfdp4OwarVjh5Y (Around the 3 minute mark I show you how to move and split windows)

[@MrNaderz]

You're a great educator Mike

[@MikeShah]

Thank you Salim!

[@parul9455]

After adding printf, why memory allocated is 1056 bytes, earlier it was 32 bytes

[@MikeShah]

timestamp? I suspect printf allocates, or at least on first use could allocate memory.

[@tweetyguy7347]

@@MikeShahit’s at the very end of the video

[@MikeShah]

@@tweetyguy7347 It seems that in printf (which is a call to vfprintf) there are several calls to malloc (example implementation: github.com/lattera/glibc/blob/master/stdio-common/vfprintf.c) -- so I suspect somewhere there's a buffer of 1024 bytes that must get allocated.

[@stepside6874]

Thank you so much. It helps me a lot.

[@MikeShah]

Cheers!

[@amitrastogi1405]

Excellent Video. Thanks!

[@MikeShah]

Cheers!

[@sallaklamhayyen9876]

Thank you So Mike you are a great teacher by NATURE 😘

[@MikeShah]

Cheers, thank you for the kind words!

[@saranshgautam3011]

nice tutorial. very helpful!

[@MikeShah]

Cheers!

[@_Anna_Nass_]

Do you have a video that covers what you did in the first few seconds of this video? I understand the C code and why we got a seg fault but I'm not as familiar with the Linux command line.

[@MikeShah]

Ah, as far as the terminal goes, check out: the Terminal Masterclass in this playlist: kzbin.info/aero/PLvv0ScY6vfd-GGT-aUH31X2yXgBSYXo6t

[@_Anna_Nass_]

@@MikeShah will do, thanks!

[@shaharrefaelshoshany9442]

AMAZING !! best explanation

[@MikeShah]

Cheers!

[@JackSparrow-tt3xg]

Professionals Use : GDB Legends use : printfs logs

[@MikeShah]

🤣 Sometimes all you have is printf :)

[@eddyecko94]

Thanks. I’m a C++ guy but I like this

[@MikeShah]

Cheers!

[@vkatasonov]

Hello, Mike. I wanted to ask if you having some problems using leaks on Mac 💻 with M chip? I was trying to use memory leaks monitoring using methods you were speaking about in other videos, but it seems with Sonoma I don’t have access to usr/bin 🤷‍♂️

[@MikeShah]

I can't remember if in that video I elevated my privileges to super user (sudo or su). That may have been necessary, or otherwise is one thing you can try. There's probably a better fix though than to have to get elevated priveleges -- though that is something I'll have to test when I upgrade my Mac.

[@vkatasonov]

@@MikeShah Thx a lot, if you will have answer to this issue I would be very appreciate. I'm trying to solve this problem as soon as I'm passing a huge course of C programming and that tool was absolutely magic for me. Everytime I run leaks --atExit-- , I have that crazy 2185 segmentation fault sudo leaks --atExit-- . I was trying to switch off SIP, but it still doesn't work. And it seems that $PATH I have introduce correctly because there is leaks tool in the system which leaks /usr/bin/leaks

[@MikeShah]

@@vkatasonov Worse case if you can use a VM on valgrind that should immediately reveal answers. Otherwise, this may be a helpful post in regards to Mac and Sonoma: forums.developer.apple.com/forums/thread/738804

[@vkatasonov]

@@MikeShah I was trying to use VM on UTM but valgrind there doesn’t work. The only solution I see is Docker with Linux or idx from google

[@CarlosLeePerez]

I have two follow up questions about Valgrind. I am currently having difficulty getting to the stage you are on, thanks to my Linux Lite naivete. How would you recommend, I create the right environment on Linux Lite to go from merely having Valgrind installed to allowing the terminal to recognize the valgrind command, which you used? Secondly, is my asking this sort of question here in the comments a good way of reaching out to you?

[@MikeShah]

Hi Carlos, yes comments are a good way to reach out, I try to give one response to as many as I can--though cannot debug 1:1 with folks :) If Ubuntu is an option, that'll setup the environment right away. If you're constrained to Linux Lite, then my guess is you're missing some base packages or dependencies for Valgrind. I'd reach out directly through their contact otherwise: www.valgrind.org/downloads/current.html

[@matheens6689]

How to check vptr and v table in c++

[@MikeShah]

info vtbl will do the trick. I show some of this on my "Hands on Debugging" course on courses.mshah.io/

[@paulfloyd9258]

Even more fun (for users): using valgrind vgdb and gdb together.

[@MikeShah]

Cheers -- agreed!

[@sallaklamhayyen9876]

Mike since you are a professional C++ developer can you make a practical and hands on Object Oriented programming course and share with us your experience ?

[@MikeShah]

Will consider developing something in the future :)

[@sallaklamhayyen9876]

@@MikeShah thank you for your time and efforts

[@Quancept]

thanks Mike :)

[@MikeShah]

You are most welcome!

[@cprn.]

I'm disappointed you didn't mention you can run `valgrind --vgdb=yes` and connect gdb to valgrind.

[@MikeShah]

Will have to be another video :)

[@HsuChiChen]

thx a lot!!

[@MikeShah]

Cheers!