C Memory Leak Problem
your program did not free all of the memor开发者_运维百科y it allocated
==17711== Memcheck, a memory error detector
==17711== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al.
==17711== Using Valgrind-3.5.0 and LibVEX; rerun with -h for copyright info
==17711== Command: ./counter
==17711==
==17711== Conditional jump or move depends on uninitialised value(s)
==17711== at 0x400B98: main (counter.c:105)
==17711==
==17711== Conditional jump or move depends on uninitialised value(s)
==17711== at 0x400BDB: main (counter.c:107)
==17711==
==17711== Conditional jump or move depends on uninitialised value(s)
==17711== at 0x400C1B: main (counter.c:109)
==17711==
error
==17711==
==17711== HEAP SUMMARY:
==17711== in use at exit: 64 bytes in 4 blocks
==17711== total heap usage: 4 allocs, 0 frees, 64 bytes allocated
==17711==
==17711== LEAK SUMMARY:
==17711== definitely lost: 0 bytes in 0 blocks
==17711== indirectly lost: 0 bytes in 0 blocks
==17711== possibly lost: 0 bytes in 0 blocks
==17711== still reachable: 64 bytes in 4 blocks
==17711== suppressed: 0 bytes in 0 blocks
==17711== Rerun with --leak-check=full to see details of leaked memory
==17711==
==17711== For counts of detected and suppressed errors, rerun with: -v
==17711== Use --track-origins=yes to see where uninitialised values come from
==17711== ERROR SUMMARY: 3 errors from 3 contexts (suppressed: 6 from 6)
make: *** [test_counter] Error 1
I have a memory leak in this program... i am pretty sure i already free all my dynamic memory.. I don't understand where the leak is =\
#include "counter.h"
/* ============================================================================
* File-global variables
* ========================================================================== */
static int ncounters = 0;
static struct counter *counters = NULL;
static int nthreads = 0;
static int *ninstructions = NULL;
static struct instruction **instructions = NULL;
/* ============================================================================
* Operations
* ========================================================================== */
static void
decrement(long long *n) {
(*n)--;
}
static void
increment(long long *n) {
(*n)++;
}
static void
mult2(long long *n) {
(*n)=(*n)*2;
}
/* ============================================================================
* Helper functions
* ========================================================================== */
pthread_mutex_t lock1;
/* ============================================================================
* Thread function
* ========================================================================== */
static void *
worker_thread(void *arg) {
pthread_mutex_lock( &lock1 );
long long n = (long long)arg;
for(int i=0; i < ninstructions[n] ;i++){
for(int j=0; j < instructions[n][i].repetitions ;j++){
(*instructions[n][i].work_fn)(&((instructions[n][i].counter)->counter));
}
}
pthread_mutex_unlock( &lock1 );
return NULL;
}
/* ============================================================================
* Main function
* ========================================================================== */
int
main(void) {
scanf(" %d", &ncounters); //Ask for number of counters
int i;
if((counters = malloc(sizeof(struct counter)*ncounters))){
for( i=0; i < ncounters ;i++){
counters[i].counter = 0;
}
}
scanf(" %d", &nthreads); //Ask for number of threads
if((ninstructions = (int*) malloc(nthreads*sizeof(int)))){
for( i=0; i < nthreads ;i++){
ninstructions[i] = 0;
}
}
instructions = malloc(nthreads*sizeof(struct instruction *));
for(i=0; i < nthreads ;i++){
scanf(" %d", &ninstructions[i]); //Ask for number of instructions within threads[i]
instructions[i] = malloc(ninstructions[i]*sizeof(struct instruction));
for(int j=0;j < ninstructions[i] ;j++){
int Srepetition;
char Sfunction;
int Scounter;
scanf(" %d %c %d", &Scounter, &Sfunction, &Srepetition);
instructions[i][j].repetitions = Srepetition;
instructions[i][j].counter = (counters+Scounter);
if(Sfunction == 'I'){
instructions[i][j].work_fn = increment;
}else if(Sfunction == 'D'){
instructions[i][j].work_fn = decrement;
}else if(Sfunction == '2'){
instructions[i][j].work_fn = mult2;
}else{
printf("error\n");
}
}
}
pthread_t thread_id[nthreads];
for(long long i=0; i < nthreads ;i++){
pthread_create( &thread_id[i], NULL, worker_thread, (void *)i);
}
for(int i=0; i < nthreads ;i++){
pthread_join( thread_id[i], NULL);
}
for(i=0; i < ncounters ;i++){
printf("%lld\n", counters[i].counter);
}
for(int i=0; i< nthreads;i++){
free(instructions[i]);
}
free(instructions);
free(ninstructions);
free(counters);
return 0;
}
You free the memory that instructions
occupies:
free(instructions);
Then you access that memory:
for(int i=0 ; i < nthreads ; i++){
free(instructions[i]);
}
You cannot access instructions
after you free(instructions)
.
You need to free the pointers in instructions
first, then free the instructions
array.
Please add option --leak-check=full
and maybe --show-reachable=yes
to Valgrind and post result together with current source code. Of course run Valgrind against debug version of your executable.
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