Description:

I have created the simplest possible Mysql client in C with the Mysql C API. The program connects to a local Mysql server and immediately disconnects from it. This sequence causes a small memory leak, as reported by Microsoft debug CRT's _CrtDumpMemoryLeaks() function.

The test program is built with Microsoft Visual C++ as a debug version (using "Debug Multithreaded" run-time library). The test program is included at the end of this description.

_CrtDumpMemoryLeaks() checks which objects allocated during the lifetime of a program are not freed at the time _CrtDumpMemoryLeaks() is called. It outputs the following:

374: Detected memory leaks! 374: Dumping objects -> 374: {50} normal block at 0x008F0100, 64 bytes long. 374: Data: <...................> CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD 374: {39} normal block at 0x008F02E0, 60 bytes long. 374: Data: <...................> 02 00 00 00 00 00 00 00 5C 00 00 00 B0 7D FA 77 374: Object dump complete.

The first block (50) is allocated by the mysql_init() call and the second block (39) is allocated by the mysql_real_connect() function. I assume they should be freed by the clean-up function mysql_close(), but they aren't.

I know this is marginal problem as the leaks probably occur only once during the lifetime of a program. However, I have some leak-detection code included in my program, and the leaks by Mysql C API cause the detection code to trigger an alarm every time.

The test program follows:

#include <windows.h> #include <stdio.h> #include <mysql.h>

int main() { MYSQL *myData;

if (!(myData = mysql_init((MYSQL*) 0))) { printf ("mysql_init() failed.\n"); }

if (!mysql_real_connect( myData, NULL, NULL, NULL, NULL, MYSQL_PORT, NULL, 0 ) ) { printf( "Can't connect to the mysql server.\n"); }

mysql_close (myData);

_CrtDumpMemoryLeaks();

return (0); }

How-To-Repeat: See above.

Fix:

Exectutable: mysqld-nt Environment: Pentium 400 MHz, 384 MB RAM, 1 GB free HD System: NT Compiler: VC++ 6.0 Architecture: i