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

Error Injection
WDB supports error injection features to debug out-of-memory events in an application.
It enables you to simulate out-of-memory conditions in an application and analyze the
behavior of the applications under such conditions. In addition, it enables you to gain
control over program execution when an out-of-memory event occurs.
To simulate an out-of-memory condition, you must use the set heap-check
null-check command to force malloc() to return NULL after <N> or a random
number of allocations. After simulating the out-of-memory error, you can use the catch
nomem command to gain control over the execution when an out-of-memory error occurs.
Table 8 lists the commands available for error injection.
Table 8 Commands for Error Injection
DescriptionCommand
Forces malloc() to return NULL after <N>
invocations of malloc().
Example 4 (page 30) illustrates the use of this
command.
set heap-check null-check <N>
Forces malloc() to return NULL after <N> bytes
are allocated by the program.
Example 5 (page 32) illustrates the use of this
command.
set heap-check null-check-size <N>
Forces malloc() to return NULL after random
number of invocations of malloc().
Example 6 (page 34) illustrates the use of this
command.
set heap-check null-check random
Defines the range for random number calculation for
the set heap-check null-check random
command
set heap-check random-range <N>
Defines the seed-value for random number calculation
for the set heap-check null-check random
command
set heap-check seed-value <N>
Enables the user to gain control over an
out-of-memory event. The user can step through
program execution after the nomem event is detected.
catch nomem
Memory-Debugging Features of WDB 29