Debugging Dynamic Memory Usage Errors Using HP WDB

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 31) 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 33) 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 35) 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