8
这里是一段代码，其中段故障发生时（在PERROR不被调用）：malloc的分段故障
job = malloc(sizeof(task_t));
if(job == NULL)
perror("malloc");
为了更精确，GDB说，segfault发生一个__int_malloc呼叫，在其内部是由malloc进行的子例程调用。
由于malloc函数与其他线程并行调用，最初我认为它可能是问题。 我使用glibc的版本2.19。
的数据结构：
typedef struct rv_thread thread_wrapper_t;
typedef struct future
{
pthread_cond_t wait;
pthread_mutex_t mutex;
long completed;
} future_t;
typedef struct task
{
future_t * f;
void * data;
void *
(*fun)(thread_wrapper_t *, void *);
} task_t;
typedef struct
{
queue_t * queue;
} pool_worker_t;
typedef struct
{
task_t * t;
} sfuture_t;
struct rv_thread
{
pool_worker_t * pool;
};
现在在今后实现：
future_t *
create_future()
{
future_t * new_f = malloc(sizeof(future_t));
if(new_f == NULL)
perror("malloc");
new_f->completed = 0;
pthread_mutex_init(&(new_f->mutex), NULL);
pthread_cond_init(&(new_f->wait), NULL);
return new_f;
}
int
wait_future(future_t * f)
{
pthread_mutex_lock(&(f->mutex));
while (!f->completed)
{
pthread_cond_wait(&(f->wait),&(f->mutex));
}
pthread_mutex_unlock(&(f->mutex));
return 0;
}
void
complete(future_t * f)
{
pthread_mutex_lock(&(f->mutex));
f->completed = 1;
pthread_mutex_unlock(&(f->mutex));
pthread_cond_broadcast(&(f->wait));
}
线程池本身：
pool_worker_t *
create_work_pool(int threads)
{
pool_worker_t * new_p = malloc(sizeof(pool_worker_t));
if(new_p == NULL)
perror("malloc");
threads = 1;
new_p->queue = create_queue();
int i;
for (i = 0; i < threads; i++){
thread_wrapper_t * w = malloc(sizeof(thread_wrapper_t));
if(w == NULL)
perror("malloc");
w->pool = new_p;
pthread_t n;
pthread_create(&n, NULL, work, w);
}
return new_p;
}
task_t *
try_get_new_task(thread_wrapper_t * thr)
{
task_t * t = NULL;
try_dequeue(thr->pool->queue, t);
return t;
}
void
submit_job(pool_worker_t * p, task_t * t)
{
enqueue(p->queue, t);
}
void *
work(void * data)
{
thread_wrapper_t * thr = (thread_wrapper_t *) data;
while (1){
task_t * t = NULL;
while ((t = (task_t *) try_get_new_task(thr)) == NULL);
future_t * f = t->f;
(*(t->fun))(thr,t->data);
complete(f);
}
pthread_exit(NULL);
}
最后的task.c：
pool_worker_t *
create_tpool()
{
return (create_work_pool(8));
}
sfuture_t *
async(pool_worker_t * p, thread_wrapper_t * thr, void *
(*fun)(thread_wrapper_t *, void *), void * data)
{
task_t * job = NULL;
job = malloc(sizeof(task_t));
if(job == NULL)
perror("malloc");
job->data = data;
job->fun = fun;
job->f = create_future();
submit_job(p, job);
sfuture_t * new_t = malloc(sizeof(sfuture_t));
if(new_t == NULL)
perror("malloc");
new_t->t = job;
return (new_t);
}
void
mywait(thread_wrapper_t * thr, sfuture_t * sf)
{
if (sf == NULL)
return;
if (thr != NULL)
{
while (!sf->t->f->completed)
{
task_t * t_n = try_get_new_task(thr);
if (t_n != NULL)
{
future_t * f = t_n->f;
(*(t_n->fun))(thr,t_n->data);
complete(f);
}
}
return;
}
wait_future(sf->t->f);
return ;
}
该队列是lfds无锁队列。
#define enqueue(q,t) { \
if(!lfds611_queue_enqueue(q->lq, t)) \
{ \
lfds611_queue_guaranteed_enqueue(q->lq, t); \
} \
}
#define try_dequeue(q,t) { \
lfds611_queue_dequeue(q->lq, &t); \
}
无论何时调用异步的次数非常高，都会出现问题。
Valgrind的输出：
Process terminating with default action of signal 11 (SIGSEGV)
==12022== Bad permissions for mapped region at address 0x5AF9FF8
==12022== at 0x4C28737: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
是否有其他可能会使'malloc'的记账混乱？ – cnicutar
这听起来像内存在其他地方被损坏。 – imreal
这是唯一的解释，我会发布整个代码。 （这真的是一个最小的模型，有内存泄漏等）。 – guilhermemtr