所以我写了一个有趣的玩具程序，在那一刻我完成了调试思考我终于把一切都搞定了，最后一次检查valgrind给了我2个错误，因为没有释放2块内存。但错误信息对我来说真的没有意义。
==7419== 80 bytes in 1 blocks are definitely lost in loss record 1 of 2
==7419== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7419== by 0x400C77: mj_Malloc (mj.c:19)
==7419== by 0x401761: main (choco.c:93)
==7419==
==7419== 80 bytes in 1 blocks are definitely lost in loss record 2 of 2
==7419== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7419== by 0x400C77: mj_Malloc (mj.c:19)
==7419== by 0x401776: main (choco.c:94)
==7419==
==7419== LEAK SUMMARY:
==7419== definitely lost: 160 bytes in 2 blocks
main中的第94行和第93行是
mj_Thread *chocolateMakers = mj_Malloc(nMakers * sizeof *chocolateMakers);
mj_Thread *chocolateEaters = mj_Malloc(nEaters * sizeof *chocolateEaters);
由
释放mj_Free(chocolateEaters);
mj_Free(chocolateMakers);
mj_Malloc和mj_Free是用于错误检查的简单包装器。 （mj_Free表示一致性）
void *mj_Malloc(size_t size) {
void *p = malloc(size);
if (p == NULL) {
mj_Error("heap allocation failed");
}
return p;
}
void mj_Free(void *p) {
free(p);
}
如果需要，您可以看到以下整个代码。
choco.c
#include "../mj.c"
typedef struct {
int n;
mj_BlockingQueue orderQueue;
mj_BlockingQueue deliveryQueue;
} *ChocolateArgument;
ChocolateArgument ChocolateArgumentCreate(int n, mj_BlockingQueue orderQueue, mj_BlockingQueue deliveryQueue) {
ChocolateArgument this = mj_Malloc(sizeof *this);
this->n = n;
this->orderQueue = orderQueue;
this->deliveryQueue = deliveryQueue;
return this;
}
int MakeChocolates(void *data) {
ChocolateArgument argument = (ChocolateArgument)data;
while (true) {
if (mj_BlockingQueueOut(argument->orderQueue) != NULL) {
printf("chocolate maker %i going home\n", argument->n);
break;
}
int milli = mj_RandomInt(1, 1000);
mj_Sleep(milli);
printf("new chocolate (maker %i, %.3f seconds)\n", argument->n, (double)milli / 1000.0);
int *pMakerNumber = mj_Malloc(sizeof *pMakerNumber);
*pMakerNumber = argument->n;
mj_BlockingQueueIn(argument->deliveryQueue, pMakerNumber);
}
mj_Free(data);
return EXIT_SUCCESS;
}
void HireChocolateMakers(mj_Thread **pMakers, int nMakers, mj_BlockingQueue orderQueue, mj_BlockingQueue deliveryQueue) {
*pMakers = mj_Malloc(nMakers * sizeof **pMakers);
for (int i = 0; i < nMakers; i += 1) {
ChocolateArgument argument = ChocolateArgumentCreate(i + 1, orderQueue, deliveryQueue);
(*pMakers)[i] = mj_ThreadCreate(MakeChocolates, argument);
}
printf("%i chocolate makers hired\n", nMakers);
}
int EatChocolates(void *data) {
ChocolateArgument argument = (ChocolateArgument)data;
int nOrders = mj_RandomInt(1, 10);
for (int i = 0; i < nOrders; i += 1) {
mj_BlockingQueueIn(argument->orderQueue, NULL);
}
printf("chocolate eater %i ordered %i chocolates\n", argument->n, nOrders);
for (int i = 1; i <= nOrders; i += 1) {
int *pMakerNumber = mj_BlockingQueueOut(argument->deliveryQueue);
printf("maker %i -> eater %i (%i / %i)\n", *pMakerNumber, argument->n, i, nOrders);
free(pMakerNumber);
}
printf("chocolate eater %i is satisfied\n", argument->n);
mj_Free(data);
return EXIT_SUCCESS;
}
void OrderChocolates(mj_Thread **pEaters, int nEaters, mj_BlockingQueue orderQueue, mj_BlockingQueue deliveryQueue) {
*pEaters = mj_Malloc(nEaters * sizeof **pEaters);
for (int i = 0; i < nEaters; i += 1) {
ChocolateArgument argument = ChocolateArgumentCreate(i + 1, orderQueue, deliveryQueue);
(*pEaters)[i] = mj_ThreadCreate(EatChocolates, argument);
}
}
void GoHome(mj_Thread *eaters, int nEaters, mj_Thread *makers, int nMakers, mj_BlockingQueue orderQueue) {
for (int i = 0; i < nEaters; i += 1) {
mj_ThreadWait(eaters[i]);
mj_ThreadDelete(eaters[i]);
}
printf("all chocolate eaters are satisfied\n");
for (int i = 0; i < nMakers; i += 1) {
mj_BlockingQueueIn(orderQueue, NULL + 1);
}
for (int i = 0; i < nMakers; i += 1) {
mj_ThreadWait(makers[i]);
mj_ThreadDelete(makers[i]);
}
}
int main(int argc, char **argv) {
if (argc != 3) {
mj_Error("not enough arguments");
}
int nMakers = atoi(argv[1]);
int nEaters = atoi(argv[2]);
mj_RandomSeed();
mj_BlockingQueue orderQueue = mj_BlockingQueueCreate();
mj_BlockingQueue deliveryQueue = mj_BlockingQueueCreate();
mj_Thread *chocolateMakers = mj_Malloc(nMakers * sizeof *chocolateMakers);
mj_Thread *chocolateEaters = mj_Malloc(nEaters * sizeof *chocolateEaters);
HireChocolateMakers(&chocolateMakers, nMakers, orderQueue, deliveryQueue);
OrderChocolates(&chocolateEaters, nEaters, orderQueue, deliveryQueue);
GoHome(chocolateEaters, nEaters, chocolateMakers, nMakers, orderQueue);
mj_BlockingQueueDelete(orderQueue);
mj_BlockingQueueDelete(deliveryQueue);
mj_Free(chocolateEaters);
mj_Free(chocolateMakers);
return 0;
}
mj.c
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <inttypes.h>
#include <limits.h>
#include <math.h>
#include <time.h>
#include <pthread.h>
#include <semaphore.h>
void mj_Error(char *errorMessage) {
fprintf(stderr, "%s\n", errorMessage);
exit(EXIT_FAILURE);
}
void *mj_Malloc(size_t size) {
void *p = malloc(size);
if (p == NULL) {
mj_Error("heap allocation failed");
}
return p;
}
void mj_Free(void *p) {
free(p);
}
typedef struct mj_QueueElement {
void *data;
struct mj_QueueElement *next;
} *mj_QueueElement;
mj_QueueElement mj_QueueElementCreate(void) {
mj_QueueElement this = mj_Malloc(sizeof *this);
return this;
}
void mj_QueueElementDelete(mj_QueueElement this) {
mj_Free(this);
}
typedef struct {
mj_QueueElement first;
mj_QueueElement last;
} *mj_Queue;
mj_Queue mj_QueueCreate(void) {
mj_Queue this = mj_Malloc(sizeof *this);
this->first = mj_QueueElementCreate();
this->last = this->first;
return this;
}
void mj_QueueDelete(mj_Queue this) {
mj_QueueElementDelete(this->first);
mj_Free(this);
}
void mj_QueueIn(mj_Queue this, void *data) {
this->last->data = data;
this->last->next = mj_QueueElementCreate();
this->last = this->last->next;
}
void *mj_QueueOut(mj_Queue this) {
mj_QueueElement temp = this->first;
void *data = temp->data;
this->first = this->first->next;
mj_QueueElementDelete(temp);
return data;
}
typedef pthread_mutex_t *mj_Mutex;
mj_Mutex mj_MutexCreate(void) {
mj_Mutex this = mj_Malloc(sizeof *this);
pthread_mutex_init(this, NULL);
return this;
}
void mj_MutexDelete(mj_Mutex this) {
pthread_mutex_destroy(this);
mj_Free(this);
}
void mj_MutexLock(mj_Mutex this) {
pthread_mutex_lock(this);
}
void mj_MutexUnlock(mj_Mutex this) {
pthread_mutex_unlock(this);
}
typedef sem_t *mj_Semaphore;
mj_Semaphore mj_SemaphoreCreate(int n) {
mj_Semaphore this = mj_Malloc(sizeof *this);
sem_init(this, 0, n);
return this;
}
void mj_SemaphoreDelete(mj_Semaphore this) {
sem_destroy(this);
mj_Free(this);
}
void mj_SemaphoreUp(mj_Semaphore this) {
sem_post(this);
}
void mj_SemaphoreDown(mj_Semaphore this) {
sem_wait(this);
}
typedef struct {
mj_Queue queue;
mj_Mutex inLock;
mj_Mutex outLock;
mj_Semaphore emptyBlocker;
} *mj_BlockingQueue;
mj_BlockingQueue mj_BlockingQueueCreate(void) {
mj_BlockingQueue this = mj_Malloc(sizeof *this);
this->queue = mj_QueueCreate();
this->inLock = mj_MutexCreate();
this->outLock = mj_MutexCreate();
this->emptyBlocker = mj_SemaphoreCreate(0);
return this;
}
void mj_BlockingQueueDelete(mj_BlockingQueue this) {
mj_QueueDelete(this->queue);
mj_MutexDelete(this->inLock);
mj_MutexDelete(this->outLock);
mj_SemaphoreDelete(this->emptyBlocker);
mj_Free(this);
}
void mj_BlockingQueueIn(mj_BlockingQueue this, void *data) {
mj_MutexLock(this->inLock);
mj_QueueIn(this->queue, data);
mj_SemaphoreUp(this->emptyBlocker);
mj_MutexUnlock(this->inLock);
}
void *mj_BlockingQueueOut(mj_BlockingQueue this) {
mj_MutexLock(this->outLock);
mj_SemaphoreDown(this->emptyBlocker);
void *data = mj_QueueOut(this->queue);
mj_MutexUnlock(this->outLock);
return data;
}
typedef pthread_t *mj_Thread;
typedef struct {
int (*function)(void *);
void *argument;
} *mj_ThreadInfo;
mj_ThreadInfo mj_ThreadInfoCreate(int (*function)(void *), void *argument) {
mj_ThreadInfo this = mj_Malloc(sizeof *this);
this->function = function;
this->argument = argument;
return this;
}
void *mj_ThreadFunction(void *data) {
mj_ThreadInfo info = (mj_ThreadInfo)data;
info->function(info->argument);
mj_Free(data);
return NULL;
}
mj_Thread mj_ThreadCreate(int (*function)(void *), void *argument) {
mj_Thread this = mj_Malloc(sizeof *this);
mj_ThreadInfo info = mj_ThreadInfoCreate(function, argument);
if (pthread_create(this, NULL, mj_ThreadFunction, info) != 0) {
mj_Error("failed to create thread");
}
return this;
}
void mj_ThreadDelete(mj_Thread this) {
mj_Free(this);
}
void mj_ThreadWait(mj_Thread this) {
pthread_join(*this, NULL);
}
void mj_Sleep(int milli) {
struct timespec time;
time.tv_sec = milli / 1000;
time.tv_nsec = (milli % 1000) * 1000000;
nanosleep(&time, NULL);
}
uint64_t mj_RandomInt_s;
uint64_t mj_RandomInt_s2;
void mj_RandomSeed(void) {
srand((unsigned)time(NULL));
mj_RandomInt_s = rand() * rand();
mj_RandomInt_s2 = rand() * rand() * rand();
}
int mj_RandomInt(int from, int to) {
if (from > to) {
mj_Error("invalid arguments");
}
uint64_t x = mj_RandomInt_s;
uint64_t y = mj_RandomInt_s2;
mj_RandomInt_s = y;
x ^= x << 23;
x ^= x >> 17;
x ^= y ^ (y >> 26);
mj_RandomInt_s2 = x;
return (int)((x + y) % (uint64_t)(to - from + 1)) + from;
}
答案 0 :(得分：3)
您分配chocolateMakers两次（第93行，第36行）和chocolateEaters两次（第94行第62行，第62行）。在这两种情况下，您都会覆盖第一次分配产生的指针和第二次分配产生的指针。当你释放分配的内存时，你只需要使用第二次分配的指针进行一次。第一次分配的指针丢失，分配的内存永远不会被释放。