Debugging Dynamic Memory Usage Errors Using HP WDB (766161-001, March 2014)

Table 7 Commands for Leak Profiling (continued)

DescriptionCommand

This command also enables you to reduce performance

degradation. See “Settings to Manage Performance

Degradation” (page 48)

To view the leak profile, complete the following steps:

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 ()

NOTE: To get the latest memory leak details for a particular leaked block with number <num>,

you must first enter the info leak command followed by info leak <num>.