valgrind

I'm following 'Learn C the Hard Way', specifically the chapter on Valgrind . This chapter gives you a deliberately wrong program to show how Valgrind works. When I run the exercise under Valgrind I do not get line numbers in my stack trace, just '(below main)' for the errors. I am definitely compiling with the -g flag. My Valgrind output is as follows: djb@twin:~/projects/Learning/C$ valgrind ./ex4 ==5190== Memcheck, a memory error detector ==5190== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al. ==5190== Using Valgrind-3.6.1-Debian and LibVEX; rerun with -h for copyright info

Can someone provide a quick top level explanation of how Valgrind works? An example: how does it know when memory is allocated and freed? Valgrind basically runs your application in a "sandbox." While running in this sandbox, it is able to insert its own instructions to do advanced debugging and profiling. From the manual: Your program is then run on a synthetic CPU provided by the Valgrind core. As new code is executed for the first time, the core hands the code to the selected tool. The tool adds its own instrumentation code to this and hands the result back to the core, which coordinates

I have developed a pure-C implementation of FIFO lists (queues) in files fifo.h and fifo.c , and have written a test programme testfifo.c which I compile to ./bin/testfifo . The node structure is defined in list.h . I run my programme through Valgrind on OS X 10.6 like this valgrind --tool=memcheck --leak-check=full --show-reachable=yes ./bin/testfifo and get the following output ==54688== Memcheck, a memory error detector ==54688== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al. ==54688== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info ==54688== Command: bin

c++ newbie here. I've been improving my memory management skills over the last few days, and my program no longer leaks memory according to valgrind. In fact, I get no warnings from valgrind at all. However, when I add openmp loops into my code, I start to get the following errors in valgrind (memcheck): (but no definitely lost blocks) ==6417== 304 bytes in 1 blocks are possibly lost in loss record 3 of 4 ==6417== at 0x4C279FC: calloc (vg_replace_malloc.c:467) ==6417== by 0x4011868: _dl_allocate_tls (dl-tls.c:300) ==6417== by 0x6649871: pthread_create@@GLIBC_2.2.5 (allocatestack.c:570) ==6417=