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Commit 2158005b authored by Mark Michelson's avatar Mark Michelson
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Remove zombie state from threadpool altogether. 

After giving it some consideration, there's no real
use for zombie threads. Listeners can't really use the
current number of zombie threads as a way of gauging activity,
zombifying threads is just an extra step before they die that
really serves no purpose, and since there's no way to re-animate
zombies, the operation does not need to be around.

I also fixed up some miscellaneous compilation errors that
were lingering from some past revisions.



git-svn-id: https://origsvn.digium.com/svn/asterisk/team/mmichelson/threadpool@377211 65c4cc65-6c06-0410-ace0-fbb531ad65f3
parent c16371fa
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include/asterisk/threadpool.h
+ 1
− 3
View file @ 2158005b
......@@ -31,12 +31,10 @@ struct ast_threadpool_listener_callbacks {
* \param listener The threadpool listener
* \param active_threads The number of active threads in the pool
* \param idle_threads The number of idle threads in the pool
* \param zombie_threads The number of zombie threads in the pool
*/
void (*state_changed)(struct ast_threadpool_listener *listener,
int active_threads,
int idle_threads,
int zombie_threads);
int idle_threads);
/*!
* \brief Indicates that a task was pushed to the threadpool's taskprocessor
*
......
main/threadpool.c
+ 15
− 131
View file @ 2158005b
......@@ -45,11 +45,6 @@ struct ast_threadpool {
* Idle threads are those that are currenly waiting to run tasks
*/
struct ao2_container *idle_threads;
/*!
* \brief The container of zombie threads.
* Zombie threads may be running tasks, but they are scheduled to die soon
*/
struct ao2_container *zombie_threads;
/*!
* \brief The main taskprocessor
*
......@@ -84,7 +79,7 @@ struct ast_threadpool {
* This is done for three main reasons
* 1) It ensures that listeners are given an accurate portrayal
* of the threadpool's current state. In other words, when a listener
* gets told a count of active, idle and zombie threads, it does not
* gets told a count of active and idle threads, it does not
* need to worry that internal state of the threadpool might be different
* from what it has been told.
* 2) It minimizes the locking required in both the threadpool and in
......@@ -101,20 +96,7 @@ struct ast_threadpool {
enum worker_state {
/*! The worker is either active or idle */
ALIVE,
/*!
* The worker has been asked to shut down but
* may still be in the process of executing tasks.
* This transition happens when the threadpool needs
* to shrink and needs to kill active threads in order
* to do so.
*/
ZOMBIE,
/*!
* The worker has been asked to shut down. Typically
* only idle threads go to this state directly, but
* active threads may go straight to this state when
* the threadpool is shut down.
*/
/*! The worker has been asked to shut down. */
DEAD,
};
......@@ -128,7 +110,7 @@ static void *worker_start(void *arg);
static struct worker_thread *worker_thread_alloc(struct ast_threadpool *pool);
static int worker_idle(struct worker_thread *worker);
static void worker_set_state(struct worker_thread *worker, enum worker_state state);
static int worker_shutdown(void *obj, void *arg, int flags);
static void worker_shutdown(struct worker_thread *worker);
/*!
* \brief Notify the threadpool listener that the state has changed.
......@@ -140,9 +122,8 @@ static void threadpool_send_state_changed(struct ast_threadpool *pool)
{
int active_size = ao2_container_count(pool->active_threads);
int idle_size = ao2_container_count(pool->idle_threads);
int zombie_size = ao2_container_count(pool->zombie_threads);
pool->listener->callbacks->state_changed(pool->listener, active_size, idle_size, zombie_size);
pool->listener->callbacks->state_changed(pool->listener, active_size, idle_size);
}
/*!
......@@ -220,41 +201,6 @@ static void threadpool_active_thread_idle(struct ast_threadpool *pool,
ast_taskprocessor_push(pool->control_tps, queued_active_thread_idle, pair);
}
/*!
* \brief Kill a zombie thread
*
* This runs from the threadpool's control taskprocessor thread.
*
* \param data A thread_worker_pair containing the threadpool and the zombie thread
* \return 0
*/
static int queued_zombie_thread_dead(void *data)
{
struct thread_worker_pair *pair = data;
ao2_unlink(pair->pool, pair->worker);
threadpool_send_state_changed(pair->pool);
ao2_ref(pair, -1);
return 0;
}
/*!
* \brief Queue a task to kill a zombie thread
*
* This is called by a worker thread when it acknowledges that it is time for
* it to die.
*/
static void threadpool_zombie_thread_dead(struct ast_threadpool *pool,
struct worker_thread *worker)
{
struct thread_worker_pair *pair = thread_worker_pair_alloc(pool, worker);
if (!pair) {
return;
}
ast_taskprocessor_push(pool->control_tps, queued_zombie_thread_dead, pair);
}
/*!
* \brief Execute a task in the threadpool
*
......@@ -322,10 +268,6 @@ static void *threadpool_alloc(struct ast_taskprocessor_listener *listener)
if (!pool->idle_threads) {
return NULL;
}
pool->zombie_threads = ao2_container_alloc(THREAD_BUCKETS, worker_thread_hash, worker_thread_cmp);
if (!pool->zombie_threads) {
return NULL;
}
pool->tps = listener->tps;
......@@ -470,11 +412,9 @@ static void threadpool_tps_emptied(struct ast_taskprocessor_listener *listener)
static void threadpool_tps_shutdown(struct ast_taskprocessor_listener *listener)
{
struct ast_threadpool *pool = listener->private_data;
int flags = (OBJ_UNLINK | OBJ_NOLOCK | OBJ_NODATA | OBJ_MULTIPLE);
ao2_cleanup(pool->active_threads);
ao2_cleanup(pool->idle_threads);
ao2_cleanup(pool->zombie_threads);
}
/*!
......@@ -537,7 +477,6 @@ static void grow(struct ast_threadpool *pool, int delta)
*/
static int kill_threads(void *obj, void *arg, int flags)
{
struct worker_thread *worker = obj;
int *num_to_kill = arg;
if ((*num_to_kill)-- > 0) {
......@@ -547,46 +486,12 @@ static int kill_threads(void *obj, void *arg, int flags)
}
}
/*!
* \brief ao2 callback to zombify a set number of threads.
*
* Threads will be zombified as long as as the counter has not reached
* zero. The counter is decremented with each thread that is zombified.
*
* Zombifying a thread involves removing it from its current container,
* adding it to the zombie container, and changing the state of the
* worker to a zombie
*
* This callback is called from the threadpool control taskprocessor thread.
*
* \param obj The worker thread that may be zombified
* \param arg The pool to which the worker belongs
* \param data The counter
* \param flags Unused
* \retval CMP_MATCH The zombified thread should be removed from its current container
* \retval CMP_STOP Stop attempting to zombify threads
*/
static int zombify_threads(void *obj, void *arg, void *data, int flags)
{
struct worker_thread *worker = obj;
struct ast_threadpool *pool = arg;
int *num_to_zombify = data;
if ((*num_to_zombify)-- > 0) {
ao2_link(pool->zombie_threads, worker);
worker_set_state(worker, ZOMBIE);
return CMP_MATCH;
} else {
return CMP_STOP;
}
}
/*!
* \brief Remove threads from the threadpool
*
* The preference is to kill idle threads. However, if there are
* more threads to remove than there are idle threads, then active
* threads will be zombified instead.
* threads will be removed too.
*
* This function is called from the threadpool control taskprocessor thread.
*
......@@ -595,20 +500,15 @@ static int zombify_threads(void *obj, void *arg, void *data, int flags)
*/
static void shrink(struct ast_threadpool *pool, int delta)
{
/*
* Preference is to kill idle threads, but
* we'll move on to deactivating active threads
* if we have to
*/
int idle_threads = ao2_container_count(pool->idle_threads);
int idle_threads_to_kill = MIN(delta, idle_threads);
int active_threads_to_zombify = delta - idle_threads_to_kill;
int active_threads_to_kill = delta - idle_threads_to_kill;
ao2_callback(pool->idle_threads, OBJ_UNLINK | OBJ_NOLOCK,
kill_threads, &idle_threads_to_kill);
ao2_callback_data(pool->active_threads, OBJ_UNLINK | OBJ_NOLOCK,
zombify_threads, pool, &active_threads_to_zombify);
ao2_callback(pool->active_threads, OBJ_UNLINK | OBJ_NOLOCK,
kill_threads, &active_threads_to_kill);
}
/*!
......@@ -629,7 +529,7 @@ struct set_size_data {
static struct set_size_data *set_size_data_alloc(struct ast_threadpool *pool,
unsigned int size)
{
struct set_size_data *ssd = ao2_alloc(sizeof(*ssd), set_size_data_destroy);
struct set_size_data *ssd = ao2_alloc(sizeof(*ssd), NULL);
if (!ssd) {
return NULL;
}
......@@ -654,22 +554,20 @@ static int queued_set_size(void *data)
{
struct set_size_data *ssd = data;
struct ast_threadpool *pool = ssd->pool;
unsigned int num_threads = ssd->size;
/* We don't count zombie threads as being "live when potentially resizing */
unsigned int new_size = ssd->size;
unsigned int current_size = ao2_container_count(pool->active_threads) +
ao2_container_count(pool->idle_threads);
if (current_size == num_threads) {
if (current_size == new_size) {
ast_log(LOG_NOTICE, "Not changing threadpool size since new size %u is the same as current %u\n",
num_threads, current_size);
new_size, current_size);
return 0;
}
if (current_size < num_threads) {
grow(pool, num_threads - current_size);
if (current_size < new_size) {
grow(pool, new_size - current_size);
} else {
shrink(pool, current_size - num_threads);
shrink(pool, current_size - new_size);
}
threadpool_send_state_changed(pool);
......@@ -777,8 +675,6 @@ static int worker_thread_cmp(void *obj, void *arg, int flags)
*/
static void worker_shutdown(struct worker_thread *worker)
{
struct worker_thread *worker = obj;
worker_set_state(worker, DEAD);
if (worker->thread != AST_PTHREADT_NULL) {
pthread_join(worker->thread, NULL);
......@@ -866,18 +762,6 @@ static void worker_active(struct worker_thread *worker)
alive = worker_idle(worker);
}
}
/* Reaching this portion means the thread is
* on death's door. It may have been killed while
* it was idle, in which case it can just die
* peacefully. If it's a zombie, though, then
* it needs to let the pool know so
* that the thread can be removed from the
* list of zombie threads.
*/
if (worker->state == ZOMBIE) {
threadpool_zombie_thread_dead(worker->pool, worker);
}
}
/*!
......
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