CentOS6.9 (MySql v5.7.22) use mysql C API mysql_real_query cause the memory always

[gamehan101]

I test the mysql_real_quer y API, I just loop to execute Sql syntax ,like 'UPDATE ** SET **' there is a leak memory bug occur. when I use 'top' to check the bug, I find the system 'used memory' option will always growing until the system or process crush. but 'mysqld' and 'testsql' processes's %MEM option has not increase, System free memory look like disappear. I try to force kill the 'testsql' process but the memory still be used and can not be release. Why? Please help me.

int ThreadExeSQL(MYSQL* lpSQLConn, char * sql, int iLen)
{

    if (mysql_real_query(lpSQLConn, sql, iLen))
    {
        MYSQL_RES* lpGetSQLRes = mysql_store_result(lpSQLConn);
        mysql_free_result(lpGetSQLRes);
        return -1;
    }

    //mysql_errno(lpSQLConn);
    //mysql_error(lpSQLConn);

    MYSQL_RES* lpGetSQLRes = mysql_store_result(lpSQLConn);
    mysql_free_result(lpGetSQLRes); // release sql memory

    return 0; // success
}

void* ThreadSQL_HexWrite(void* lpGet)
{

    LPThreadParam getParam = (LPThreadParam)lpGet;

    MYSQL* lpSQLConn = (MYSQL*)&getParam->lpSQLConn;
    int iThreadIdx = getParam->iThreadIdx;

    printf("ID:%d\n", iThreadIdx);

    mysql_thread_init();

    lpSQLConn = mysql_init(NULL);


    if (!mysql_real_connect(lpSQLConn, g_host_name, g_user_name, g_password, g_db_name, g_db_port, NULL, 0))
    {
        ThreadSQLError(lpSQLConn, NULL);
        return;
    }
    else
    {
        printf("mysql_real_connect OK!\n");
    }


    for (int i = 0; i < 1000000; i++)
    {

        char lpCmdStr[8192] = "\0";
        sprintf(lpCmdStr, "update %s set %s=0x%d where id=%d\0", "tb_Data", "Info", i, 1);

        if (ThreadExeSQL(lpSQLConn, (char*)lpCmdStr, strlen(lpCmdStr)))
        {
            MySQLError getError = ThreadSQLError(lpSQLConn, NULL);
            HandleMySqlError(getError);

            return; //erroe
        }
        else
        {
            printf("ok. ");
        }

        usleep(1000 * 10);
    }

    mysql_close(lpSQLConn);

    mysql_thread_end();


    printf("ThreadSQL_HexWrite OK!\n");
}


MYSQL* g_MySQLConnList[100];

void main()
{

    if (mysql_library_init(0, NULL, NULL))
    {
        printf("could not initialize MySQL client library\n");
        exit(1);
    }


    int thread_num = 1;

    //while (true)
    {
        pthread_t *pTh = new pthread_t[thread_num];


        for (int i = 0; i < thread_num; i++)
        {

            LPThreadParam lpSetParam = new ThreadParam;
            lpSetParam->lpSQLConn = (MYSQL*)&g_MySQLConnList[i];
            lpSetParam->iThreadIdx = i;

            printf("---create thread idx:%d\n", i);
            if (0 != pthread_create(&pTh[i], NULL, ThreadSQL_HexWrite, lpSetParam))
            {
                printf("pthread_create failed\n");
                continue;
            }
        }

        for (int i = 0; i < thread_num; i++)
        {
            pthread_join(pTh[i], NULL);
        }

        delete[] pTh;
    }

    mysql_library_end();

    printf("All Done!\n");

}

[gamehan101]

for (int i = 0; i < 1000000; i++) 
{
 ......
  if (ThreadExeSQL...)
   { 
      ...... 
      continue; // this line change to continue; code copy with a little mistake. 
    } 

}