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Release Date: Oct-23-1998
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The following key files are included in the sample:
FileName Description
---------------------------------------------------------
PDH.dll Contains helper functions used by PHD.
RKLeak.cpp Contains the code for the PHD class.
RKLeak.h Header file for the PHD class.
TestMain.cpp A simple program to demonstrate the PHD class.
To use the PHD class, include the RKLeak.cpp file in your project. By
including the header file, you will cause linkage to the PDH.lib library,
which comes with the Visual C++ 6.0. You also need to add the PHD.dll file
to your path so that the application will find it.
The TestMain.cpp file contains the following sample code that demonstrates
how to use the PHD class:
Sample Code
**************************************************
#include "rkLeak.h"
void main()
{
char *myCntrs[]={
"\\Memory\\Available bytes",
"\\Memory\\committed bytes",
"\\Memory\\pool Paged bytes",
"\\Memory\\pool Nonpaged bytes",
};
PHD mphd2(myCntrs,sizeof(myCntrs)/sizeof(myCntrs[0]));
PHD mphd;
const int arSize=4096;
for (int i=0;i<5;i++){
double *d = new double[arSize];
d[0]= 1.; d[arSize-1] = 2.; // Force to committed mem.
mphd.logData(i);
mphd2.logData(i);
}
***************************************************
The first use of the PHD constructor allows you to specify which items you
want to monitor. These are the same items that are available in the
Perfmon.exe application.
The second use of the PHD constructor (no arguments) uses the following
default column logs: private bytes, page file bytes, pool paged bytes, pool
nonpaged bytes, and working set.
As you can see from the sample code, the PHD class is used to put the
suspected leaking API in a loop and periodically calls the PHD::logData
method. Data is logged to file with name "<your EXE name>_perf.log" in the
current directory. If the resulting log file shows a linear increase in
private bytes, this increase does not imply a memory leak in the API, but
merely a memory leak in the application. If the API is used incorrectly
(for example, by not correctly freeing resources allocated by the initial
call), the results show only a memory leak, not a faulty API. To narrow
down the problem, create the simplest possible application that exercises
the API in question.
Visual C++ 5.x users need to comment out the following lines from RKLeak.h:
#undef PdhOpenQuery // PdhOpenQueryA
extern "C" long __stdcall
PdhOpenQuery (
IN LPCSTR szDataSource,
IN DWORD dwUserData,
IN HQUERY *phQuery
);
Other Tools
You can search on the Web in FAQ pages for information on various third-
party debuggers that can help you find memory leaks. For example, the
following FAQ mentions several products:
The third-party products discussed here are manufactured by vendors
independent of Microsoft; we make no warranty, implied or otherwise,
regarding these products' performance or reliability. You should also note
that sometimes these products can make false reports of leaks, but they
still are very useful tools.
Also, the Visual C++ heap debugging API is a useful tool for locating
leaks. These include functions, such as _CrtMemDifference() and
_CrtMemDumpAllObjectsSince(), which are documented in the Visual C++
Programmer's Guide in the Debug Function Reference section. These functions
only detect leaks in your code and not leaks in other components.
(c) Microsoft Corporation 1998, All Rights Reserved. Contributions by Rick
Anderson, Microsoft Corporation.