[En-Nut-Discussion] File descriptor leak in 4.8.7

[Coleman Brumley]

After doing some arithmetic, it appears that each occurrence of "Creating
stream device failed" causes a 1271 byte leak from heap space. Does that
number ring a bell? 

 

I've re-verified that this does not happen unless a browser is making HTTP
requests of the controller. If the controller is just "sitting there", there
is no leak. I verify this via a printout of available heap space every 30
minutes. After running for 4 hours, there were no leaks. 

 

While there is no set time between each occurrence, this does seem to happen
about 5 times in 30 minutes. 

 

The errno value 23 means that too many files are open, correct? FOPEN_MAX is
defined as 8, so is having six concurrent HTTP threads running too many? Is
it possible that the use of multiple HTTP threads without using a mutex is
causing the file open handles to corrupt somehow and therefore not be closed
correctly?  

 

Coleman

 

From: Coleman Brumley [mailto:cbrumley at polarsoft.biz] 
Sent: Monday, May 04, 2015 1:19 PM
To: en-nut-discussion at egnite.de
Subject: File descriptor leak in 4.8.7

 

Everyone,

 

I'm working with Nut/OS v4.8.7 (for many, many reasons, I CANNOT upgrade the
core OS). The processor is an Atmel SAM7X256.

 

I'm encountering a problem with the use of file descriptors in HTTP, and I
believe the core effect is a resource leak. 

 

Here is my HTTP service code:

 

THREAD(Service, arg)

{

       TCPSOCKET *sock;

       FILE *stream;

       u_char id = (u_char) ((uptr_t) arg);

      u_char timeout=0;

       time_t t;

       struct _tm tmx ;

       uint16_t lowheapcounter=1000;

NutThreadSetPriority(72);  

 

    /*

     * Now loop endless for connections.

     */

 

    for (;;) {

 

        /*

         * Create a socket.

         */

              if ((sock = NutTcpCreateSocket()) == 0) 

              {

                     printf("[%u] Creating socket failed\n", id);

                     NutSleep(5000);

                     continue;

              }    

        /*

         * Listen on port 80. This call will block until we get a connection

         * from a client.

         */

        NutTcpAccept(sock, 80);

      

 

        /*

         * Detect low heap and if it happens for too long, reset.

         *

         */

              while (NutHeapAvailable() < 4096) {

                     t=time(0l);

                     localtime_r(&t,&tmx);

                     printf("%02d:%02d:%02d %02d-%02d-%04d -- ",

                           tmx.tm_hour,

                           tmx.tm_min,

                           tmx.tm_sec,

                           tmx.tm_mon+1,

                           tmx.tm_mday,

                           tmx.tm_year+1900);

                     printf("[%u] Low mem (%d)\n", id,
(int)NutHeapAvailable());

                     NutSleep(1000);

                     lowheapcounter--;

                     if(lowheapcounter<=0) Hreset();

              }

 

        /*

         * Associate a stream with the socket so we can use standard I/O
calls.

         */

              

              while (((stream = _fdopen((int) ((uptr_t) sock), "r+b")) ==
0)&&(++timeout<0xFF)) 

              {

                     NutSleep(10);

              } 

              if(!stream)

              {

                     printf("\n[%u] Creating stream device failed w/
errno:%d\n", id,errno);

NutTcpCloseSocket(sock);

                     continue;

              }

              else

              {         

                     NutHttpProcessRequest(stream);            

                     fclose(stream);

                     NutTcpCloseSocket(sock);

              }

    }

}

 

The console output shows all is normal initially, but after a while (approx.
765 seconds, initially after boot time) I start seeing"

 

[3] Creating stream device failed w/ errno:23

 

Where the number in braces is the thread id. I'm running 6 HTTP threads,
started as follows:

for (i = 1; i <= 6; i++) 

{

char thname[] = "httpd0";

        thname[5] = '0' + i;

        NutThreadCreate(thname, Service, (void *) (uptr_t)
i,HTTPD_SERVICE_STACK);

}     

 

The stack size is defined as 1024. 

 

I noticed this question was asked some time ago on this list, but I could
not determine if there was ever a solution posted. There are other I/O
processes running in the controller, but it ONLY runs low on resources when
a browser is connected to it. 

 

Does anyone have any suggestions as to what I could look into as to what
might be the problem? 

 

While the browser(s) are connected, the system appears to lose about 4.5k of
heap space per 30 minutes! 

 

Thanks in advance.

 

Best Regards,

Coleman