Debugging Dynamic Memory Usage Errors Using HP WDB v6.3 (5900-2181, August 2012)

For more information on the HP aC++ compiler options for memory debugging, see the HP C

World Wide Webpage at:

http://www.hp.com/go/c

Memory Checking Analysis for User Defined Memory Management Routines

Many user applications have their own memory management routines. These custom allocator

routines are either user defined or sometimes wrappers to the default memory management routines.

Memory checking features have been extended for user defined memory management routines.

Memory leak, prole of heap memory, or memory errors can be obtained for user defined memory

management routines.

Following are the limitations for user-defined memory management routines:

• This feature routes to default memory routines instead of calling user defined memory

management routines to obtain memory analysis.

• This feature is not supported in batch mode and attach mode debugging.

Memory-Debugging Features of WDB

WDB supports the following memory-debugging features:

• Heap Profiling features

• Leak Profiling feature

• Error Injection features

• Event Monitoring features

In addition to these features, HP WDB provides the following generic commands for memory

debugging:

Table 3 Generic Commands for Memory Checking

DescriptionCommand

Toggles the setting of commands for detecting leaks,

bounds, double frees, and heap profiling.

set heap-check <on/off>

Displays the current settings for memory checkingshow heap-check

NOTE: GDB reports an incorrect stack trace after dlclose or shl_unload, and a subsequent

dlopen or shl_load. The leaks are displayed erroneously when the memory address range

overlaps between the newly loaded shared library, and the recently unloaded shared library.

Workaround: Place a breakpoint at dlclose or shl_unload, and enter the info leaks

command to view the leaks accurately when a shared library is unloaded.

Heap Profiling

You can profile the heap usage in an application by using WDB. The heap-profiling feature enables

you to analyze the influence of algorithms and data structures on heap usage and tune the memory

requirements of an application.

WDB supports the following heap-analysis profiles:

• Snapshot Profile

• Incremental Heap Profile

• Arena Profile

NOTE: Heap profiling must be enabled to view heap reports. The set heap-check on

command enables heap profiling also.