How to track down a "double free or corruption" error

Solution 1:

If you're using glibc, you can set the MALLOC_CHECK_ environment variable to 2, this will cause glibc to use an error tolerant version of malloc, which will cause your program to abort at the point where the double free is done.

You can set this from gdb by using the set environment MALLOC_CHECK_ 2 command before running your program; the program should abort, with the free() call visible in the backtrace.

see the man page for malloc() for more information

Solution 2:

There are at least two possible situations:

1. you are deleting the same entity twice
2. you are deleting something that wasn't allocated

For the first one I strongly suggest NULL-ing all deleted pointers.

You have three options:

1. overload new and delete and track the allocations
2. yes, use gdb -- then you'll get a backtrace from your crash, and that'll probably be very helpful
3. as suggested -- use Valgrind -- it isn't easy to get into, but it will save you time thousandfold in the future...