Debugging Dynamic Memory Usage Errors Using HP WDB (5900-1474; WDB 6.2; January 2011)

1. Run the debugger and load the program by entering the following command:

$ gdb <executable> <arguments>

$ gdb –leaks <executable> <arguments>

2. Enable leak checking by entering the following command:

(gdb) set heap-check leaks on

(if the –leaks option is not used in Step 1)

NOTE: Alternatively, you can use the set heap-check on command to

automatically enable the detection of leaks by toggling the set heap-check

leaks on command. This command enables the detection of leaks, heap profiles,

bounds checking, and checking for double frees.

3. Set breakpoints in the code at probe-points where you want to examine cumulative

leaks by entering the following command:

(gdb) b <probe-points>

4. Run the program in the debugger by entering the following command:

(gdb) run

5. When the breakpoint triggers, enter the following info leaks command to display

the list of memory leaks:

(gdb) info leaks

The following output is displayed:

Scanning for memory leaks...done

2439 bytes leaked in 25 blocks

No. Total bytes Blocks Address Function

0 1234 1 0x40419710 foo()

1 333 1 0x40410bf8 main()

2 245 8 0x40410838 strdup()

[...]

The debugger assigns a numeric identifier for each leak. To view a stack trace for

a specific leak, specify the leak number from the list of leaks, as follows:

(gdb) info leak 2

245 bytes leaked in 8 blocks (10.05% of all bytes leaked)

These range in size from 26 to 36 bytes and are allocated in strdup ()

in link_the_list () at test.c:55

in main () at test.c:13

in _start ()