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mistake with Heap

DAndy boy

Hi!

I use RTX.
In my program except the others there are three processes
Here they

OS_MUT LOG_MUTEX;
#define INIT_LOG_LOCK os_mut_init(LOG_MUTEX)
#define LOCK_LOG os_mut_wait(LOG_MUTEX,0xFFFF)
#define RELEASE_LOG os_mut_release(LOG_MUTEX)


__task void tcp_task (void) {
   /* Main Thread of the TcpNet. This task should have */
   /* the lowest priority because it is always READY. */

        INIT_LOG_LOCK;

while (1)
{
 LOCK_LOG;
  main_TcpNet();
 RELEASE_LOG;
 os_tsk_pass();
 }
}


__task void GetHeapsState(void)
{
  char *ptr;
 unsigned int max=0;

while(1)
{
  LOCK_LOG;
  tsk_lock();

   max=1;

  do{

         ptr=(char*)malloc(max);
         if(ptr)
         {
          max+=1;
          free(ptr);
         }
   } while(ptr);

   printf("%d\r\n",max);
   tsk_unlock();
        RELEASE_LOG;
        os_dly_wait(10);
}

}

__task void CreatXML(void)
{
   FILE *file_xml = NULL;
 LOCK_LOG;
while(1)
{
 do
 {
  file_xml = fopen ("monitor.xml","w");
  if(file_xml==NULL)
         break;
  fputs("<?xml version=\"1.0\" encoding=\"WINDOWS-1251\"?><form>\r\n",file_xml);
  ....

  fputs("</form>",file_xml);
  fclose(file_xml);
  }
  while(0);
  RELEASE_LOG;
  os_dly_wait(10);
 }

}


In the beginning GetHeapsState outputs size of the maximum mount memory (number 3909 byte is output).
If I will start Explorer and begin to request periodical file monitor.xml after a little later as much as possible selected memory size in the task of GetHeapsState will: 3821 byte.
And this number will not change any more does not vary even if we will terminat the request of file monitor.xml.
Can you explain me Where disappear 88 byte? I have noticed that the given mistake appears faster if in a parallel way to begin sending any file on fttp.

Parents
  • 0 in reply to DAndy boy

    Ok. how to check up a heap state?

    first of all, the question is: what do you want to test actually? your current code may compromise system stability by creating memory fragmentation - little blocks that cannot be (re)used. but run time errors that emanate from lack of heap space available must be handled by testing for null pointers that return from allocation functions, and you probably don't want to do it the way you do above. you may want to try to allocate and release larger blocks, and less frequently. but again - TCPNet and other libraries that need heap must return error codes if they run out of heap space, as should your code, too. normally, allocating heap space occurs in the design phase of a system, when the budget of everything is taken into account - including memory requirements.

Reply
  • 0 in reply to DAndy boy

    Ok. how to check up a heap state?

    first of all, the question is: what do you want to test actually? your current code may compromise system stability by creating memory fragmentation - little blocks that cannot be (re)used. but run time errors that emanate from lack of heap space available must be handled by testing for null pointers that return from allocation functions, and you probably don't want to do it the way you do above. you may want to try to allocate and release larger blocks, and less frequently. but again - TCPNet and other libraries that need heap must return error codes if they run out of heap space, as should your code, too. normally, allocating heap space occurs in the design phase of a system, when the budget of everything is taken into account - including memory requirements.

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