freeing problem with concurrent processes

[alavardi]

the program partitions a file to several files then creates processes to sort them.

fpArray = malloc ( numOfProcesses * sizeof( FILE* ) );
processIDs = malloc ( numOfProcesses * sizeof (pid_t*));

when i check it with valgrind, there is no problem with main process but for child processes it says

32 bytes in 1 blocks are still reachable in loss record 1 of 2
==2338== at 0x1B901E28: malloc (vg_replace_malloc.c:131)
==2338== by 0x8048733: main (psort.c:50)
==2338==
==2338==
==2338== 32 bytes in 1 blocks are still reachable in loss record 2 of 2
==2338== at 0x1B901E28: malloc (vg_replace_malloc.c:131)
==2338== by 0x804871B: main (psort.c:49)

for these lines. at the end of the main process i have below lines

free (fpArray);
free (processIDs);

how can i get rid of this error

edit:

i have the same problem for the same code with threads.

[quzah]

The error isn't in any of those lines. It's in you moving your pointer around some place and losing what you allocate.

Quzah.

[alavardi]

ok, here is whole code

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
//#include <fcntl.h>
#include <unistd.h>
#include <sys/wait.h>
#include <errno.h>
#include <math.h>

#define LINE_LENGTH 1000

typedef struct heap_node{

	char* data;
	struct BinaryNode* left;
	struct BinaryNode* right;

}heapNode;

heapNode* root;

void childProcess(void);

int main (int argc, char* argv[]){

	int numOfProcesses;
	char* inputFileName;
	char* outputFileName;
	char filename[50];
	char line[LINE_LENGTH];
	int r; //M%N
	int i; //for FOR loops
	int j; //for FOR loops
	FILE** fpArray;
	FILE* inputFile;
	int numOfLines = 0;
	pid_t* processIDs;

	if( argc < 6 || argc > 7){
		printf("Wrong number of arguments\n");
		printf("Usage: \n");
		printf("psort -n <numOfProcesses> -i <inputfile> -o <outputfile> [-d]\n");
		exit(1);
	}
	else {
		numOfProcesses = atoi (argv[2]);
		inputFileName = argv[4];
		outputFileName = argv[6];
		fpArray = malloc ( numOfProcesses * sizeof( FILE* ) );
		processIDs = malloc ( numOfProcesses * sizeof (pid_t*));
		inputFile = fopen(inputFileName, "r");

		//count num of lines in the file
		while( fgets(line, sizeof(line), inputFile) ){
			 ++numOfLines;
		}
		//printf("File contains %d lines.\n", numOfLines);
		rewind (inputFile);
		for( i=0; i<numOfProcesses; ++i){
			/* make a string that will be the filename */
			sprintf(filename, "%d.%d.txt", (int) getpid (),(i+1));
			//fpArray[i] = fopen(filename, "w");
			fpArray[i] = fopen(filename, "w");
			if (fpArray[i] == NULL)
			{
	  			perror ("main():");	 //print the reason why fopen failed
	  			exit (1);
			}

		}
		r = (numOfLines%numOfProcesses);

		//partition the file
		for (i=0; i<(numOfProcesses-1); ++i ){

			//write M-r/N records to file
			for (j=0; j<((numOfLines-r)/numOfProcesses); ++j){

				fgets(line, sizeof(line), inputFile);
				fprintf(fpArray[i], "%s", line);
			}
		}
		//write (M-r/N)+r records to the last file
		for (j=0; j<(((numOfLines-r)/numOfProcesses)+r); ++j){

			fgets(line, sizeof(line), inputFile);
			//fprintf(fpArray[numOfProcesses-1], "%s", line);
			fprintf(fpArray[i], "%s", line);
		}
		for (i=0; i<(numOfProcesses); ++i ){
			fclose(fpArray[i]);
		}

		fclose(inputFile);

		//create processes
		for (i=0; i<numOfProcesses; ++i){

			processIDs[i] = fork();

			if (processIDs[i] < 0)
			{
      				perror ("main():");	 //if fork has failed,
						   	//print the reason why it has failed
      				exit (1);		 //terminate
    			}

			if (processIDs[i] == 0){
				childProcess();
			}

			//else
				//parentProcess(processID);

		}//end of create processes

		//printf("I am parent process and my pid: %d\n", (int) getpid() );

		for (i=0; i<numOfProcesses; ++i){
			waitpid(processIDs[i], NULL, 0);
		}
		/*for(i=0; i<numOfProcesses; ++i){
			free (fpArray[i]);

		}*/
		free (fpArray);
		free (processIDs);
		exit(0); //the execution shouldn't reach here
		//return 0;

	}//end of else
}//end of main

void childProcess(void){
	//printf("I am a child process and my pid: %d\n", (int) getpid() );
	//free (fpArray);
	//free (processIDs);
	exit(0);
}