Problem with plose or with waitpid !!!

[hpranava varna <hpranavvarna@xxxxxxxxx>]

Hello,

 

   I executed the following code, but it generally hangs pclose(), The problem occured with fclose as well. I am clueless abt the error in the code. I am using Fedora and redhat linux. Can you help me find the error ?. It doesnt hang if the main thread waits for the flag to be set to 1 before continuing to pclose.

 

code :

 

 #include <unistd.h>
#include <stdio.h>
#include <wait.h>
#include <pthread.h>
#include <errno.h>
#include <string.h>
#include <signal.h>
#define SIM_LOG printf

int waitDetect = 0, noOfPopen = 0, noPclose = 0,flag = 0;

void* waitThread(void*)
{
 while(true)
 {

 pid_t pid = waitpid(0,NULL,WUNTRACED); //will hang
        //pid_t pid;
//      !   pid = waitpid(-1,NULL,WUNTRACED);
 printf("wait : %d",(int)pthread_self());
 if (pid < 0)
 {
//  perror("waitpid");
 }
 else if (pid > 0)
 {
  waitDetect++;
  printf("The child pid is %d, wait detected %d children",
     pid, waitDetect);
  printf("The no of popens is %d , pclose : %d ", noOfPopen,noPclose);
  flag = 1;
 } 
 }
}

 

bool print(char* cmd)
{
   printf("print : %d", pthread_self());
   char buf1[1000], array[100];
   float cpu,mem;
   int bufsize= 1000;
   char *buf = buf1;
   FILE *fptr = popen(cmd, "r");
   noOfPopen++;

// printf("waitpid interfered \n");
 //sleep(5);

   fgets(buf, bufsize, fptr) ;
   printf("start\n");
   SIM_LOG("*********START***************");
 
   while(feof(fptr) ==0)
   {
 printf("buf is\n");
      SIM_LOG(" checkProcess :: The buffer is %s", buf);

      if((*buf == '\t') || (*buf == ' ') || (*buf == '\0'))
      {
         while (*buf != ' ' && *buf != '\t' && *buf != '\0') buf++;
         while (*buf == ' ' || *buf == '\t') buf++;
      }
  sscanf(buf, "%f", &cpu);
 printf("cpu \n");
      SIM_LOG(" getCpuMem :: The CPU Utilization is  %f\n", cpu);

      while (*buf != ' ' && *buf != '\t' && *buf != '\0') buf++;
      while (*buf == ' ' || *! buf == '\t') buf++;

      sscanf(buf, "%f", &mem);
 printf("mem\n");
      SIM_LOG(" getCpuMem :: The mem utilization is %f\n", mem);

      while (*buf != ' ' && *buf != '\t' && *buf != '\0') buf++;
      while (*buf == ' ' || *buf == '\t') buf++;

      sscanf(buf, "%s", array);
 printf("array \n");
      SIM_LOG(" getCpuMem :: The process name is %s\n", array);

      if (strcmp("bash", array) ==0)
      {
         break;
      }
      fgets(buf, bufsize, fptr);
  }
 printf("Before PCLOSE\n");
 //while(flag == 0);
 //flag = 0;
        //sleep (1);
   pclose(fptr);
//     fclose(fptr);
 printf("After PCLOSE\n");
   noPclose++;
   SIM_LOG("*********END***************");
   return true;
}

main()
{
 char *cmd = "ps -eo %cpu,%mem,cmd | grep \"bash\"";
 pthread_t tid;
    //sim_log_init("test",".");
 if ((errno = pthread_create(&tid,NULL, &waitThread, NULL)) != 0)
  perror("pthread_create");

        pid_t pid = fork();
        if(pid == 0)
        {
           sleep(20000);
        }
 while(true)
 {
  print(cmd);
  //sleep(5);
 }

}

 

 

 

 2 Thread -161203280 (LWP 3205)  0x0014d7a2 in _dl_sysinfo_int80 ()
   from /lib/ld-linux.so.2
  1 Thread -153901376 (LWP 3201)  0x0807e415 in _p1922static ()

bt on thread 1 gave :

#0  0x0807e415 in _p1922static ()
#1  0x0805b834 in __waitpid_nocancel ()
#2  0xf6dfc830 in _IO_proc_close@@GLIBC_2.1 ()
   from /opt/rational/releases/purify.i386_linux2.2003a.06.15/cache/modtestserver/lib/tls/libc.so.6_pure_p3_c0_104011552_269-1667smp_32
#3  0xf6e128ef in _IO_new_file_close_it ()
   from /opt/rational/releases/purify.i386_linux2.2003a.06.15/cache/modtestserver/lib/tls/libc.so.6_pure_p3_c0_104011552_269-1667smp_32
#4  0xf6df730c in fclose@@GLIBC_2.1 ()
   from /opt/rational/releases/purify.i386_linux2.2003a.06.15/cache/modtestserver/lib/tls/libc.so.6_pure_p3_c0_104011552_269-1667smp_32
#5  0x0808099a in print (cmd=0x808d888 "ps -eo %cpu,%mem,cmd | grep \"bash\"")
    at test2.c:98
#6  0x08080bd9 in main () at test2.c:121

 

 

bt on thread 2 gave :

#0  0x0014d7a2 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
#1  0xf6e853e6 in __wait4 ()

 

 

 

---

Yahoo! Travel
 
Find  
great deals to the top 10 hottest destinations!
_______________________________________________
Redhat-devel-list mailing list
Redhat-devel-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/redhat-devel-list