int thorium_worker_get_producer_count(struct thorium_worker *worker, struct thorium_balancer *scheduler)
{
struct core_map_iterator iterator;
int name;
struct thorium_actor *actor;
int count;
count = 0;
core_map_iterator_init(&iterator, &worker->actors);
while (core_map_iterator_get_next_key_and_value(&iterator, &name, NULL)) {
actor = thorium_node_get_actor_from_name(worker->node, name);
if (actor == NULL) {
continue;
}
if (thorium_balancer_get_actor_production(scheduler, actor) > 0) {
++count;
}
}
core_map_iterator_destroy(&iterator);
return count;
}
void thorium_balancer_balance(struct thorium_balancer *self)
{
/*
* The 95th percentile is useful:
* \see http://en.wikipedia.org/wiki/Burstable_billing
* \see http://www.init7.net/en/backbone/95-percent-rule
*/
int load_percentile_50;
struct core_timer timer;
int i;
struct core_vector loads;
struct core_vector loads_unsorted;
struct core_vector burdened_workers;
struct core_vector stalled_workers;
struct thorium_worker *worker;
struct thorium_node *node;
/*struct core_set *set;*/
struct core_pair pair;
struct core_vector_iterator vector_iterator;
int old_worker;
int actor_name;
int messages;
int maximum;
int with_maximum;
struct core_map *set;
struct core_map_iterator set_iterator;
int stalled_index;
int stalled_count;
int new_worker_index;
struct core_vector migrations;
struct thorium_migration migration;
struct thorium_migration *migration_to_do;
struct thorium_actor *actor;
int candidates;
int load_value;
int remaining_load;
int projected_load;
struct core_vector actors_to_migrate;
int total;
int with_messages;
int stalled_percentile;
int burdened_percentile;
int old_total;
int old_load;
int new_load;
int predicted_new_load;
struct core_pair *pair_pointer;
struct thorium_worker *new_worker;
/*int new_total;*/
int actor_load;
int test_stalled_index;
int tests;
int found_match;
int spawned_actors;
int killed_actors;
int perfect;
#ifdef THORIUM_SCHEDULER_ENABLE_SYMMETRIC_SCHEDULING
struct core_map symmetric_actor_scripts;
int script;
#endif
node = thorium_worker_pool_get_node(self->pool);
spawned_actors = thorium_node_get_counter(node, CORE_COUNTER_SPAWNED_ACTORS);
/* There is nothing to balance...
*/
if (spawned_actors == 0) {
return;
}
killed_actors = thorium_node_get_counter(node, CORE_COUNTER_KILLED_ACTORS);
/*
* The system can probably not be balanced to get in
* a better shape anyway.
*/
if (spawned_actors == self->last_spawned_actors
&& killed_actors == self->last_killed_actors
&& self->last_migrations == 0) {
printf("SCHEDULER: balance can not be improved because nothing changed.\n");
return;
}
/* Check if we have perfection
*/
perfect = 1;
for (i = 0; i < thorium_worker_pool_worker_count(self->pool); i++) {
worker = thorium_worker_pool_get_worker(self->pool, i);
load_value = thorium_worker_get_epoch_load(worker) * 100;
if (load_value != 100) {
perfect = 0;
break;
}
}
if (perfect) {
printf("SCHEDULER: perfect balance can not be improved.\n");
return;
}
/* update counters
*/
self->last_spawned_actors = spawned_actors;
self->last_killed_actors = killed_actors;
/* Otherwise, try to balance things
*/
core_timer_init(&timer);
core_timer_start(&timer);
#ifdef THORIUM_SCHEDULER_ENABLE_SYMMETRIC_SCHEDULING
core_map_init(&symmetric_actor_scripts, sizeof(int), sizeof(int));
thorium_balancer_detect_symmetric_scripts(self, &symmetric_actor_scripts);
#endif
#ifdef THORIUM_WORKER_ENABLE_LOCK
/* Lock all workers first
*/
for (i = 0; i < thorium_worker_pool_worker_count(self->pool); i++) {
worker = thorium_worker_pool_get_worker(self->pool, i);
thorium_worker_lock(worker);
}
#endif
core_vector_init(&migrations, sizeof(struct thorium_migration));
#ifdef THORIUM_SCHEDULER_ENABLE_VERBOSITY
printf("BALANCING\n");
#endif
core_vector_init(&loads, sizeof(int));
core_vector_init(&loads_unsorted, sizeof(int));
core_vector_init(&burdened_workers, sizeof(struct core_pair));
core_vector_init(&stalled_workers, sizeof(struct core_pair));
core_vector_init(&actors_to_migrate, sizeof(struct core_pair));
for (i = 0; i < thorium_worker_pool_worker_count(self->pool); i++) {
worker = thorium_worker_pool_get_worker(self->pool, i);
load_value = thorium_worker_get_scheduling_epoch_load(worker) * SCHEDULER_PRECISION;
#if 0
printf("DEBUG LOAD %d %d\n", i, load_value);
#endif
core_vector_push_back(&loads, &load_value);
core_vector_push_back(&loads_unsorted, &load_value);
}
core_vector_sort_int(&loads);
stalled_percentile = core_statistics_get_percentile_int(&loads, SCHEDULER_WINDOW);
/*load_percentile_25 = core_statistics_get_percentile_int(&loads, 25);*/
load_percentile_50 = core_statistics_get_percentile_int(&loads, 50);
/*load_percentile_75 = core_statistics_get_percentile_int(&loads, 75);*/
burdened_percentile = core_statistics_get_percentile_int(&loads, 100 - SCHEDULER_WINDOW);
#ifdef THORIUM_SCHEDULER_ENABLE_VERBOSITY
printf("Percentiles for epoch loads: ");
core_statistics_print_percentiles_int(&loads);
#endif
for (i = 0; i < thorium_worker_pool_worker_count(self->pool); i++) {
worker = thorium_worker_pool_get_worker(self->pool, i);
load_value = core_vector_at_as_int(&loads_unsorted, i);
set = thorium_worker_get_actors(worker);
if (stalled_percentile == burdened_percentile) {
#ifdef THORIUM_SCHEDULER_ENABLE_VERBOSITY
printf("scheduling_class:%s ",
THORIUM_CLASS_NORMAL_STRING);
#endif
} else if (load_value <= stalled_percentile) {
#ifdef THORIUM_SCHEDULER_ENABLE_VERBOSITY
printf("scheduling_class:%s ",
THORIUM_CLASS_STALLED_STRING);
#endif
core_pair_init(&pair, load_value, i);
core_vector_push_back(&stalled_workers, &pair);
} else if (load_value >= burdened_percentile) {
#ifdef THORIUM_SCHEDULER_ENABLE_VERBOSITY
printf("scheduling_class:%s ",
THORIUM_CLASS_BURDENED_STRING);
#endif
core_pair_init(&pair, load_value, i);
core_vector_push_back(&burdened_workers, &pair);
} else {
#ifdef THORIUM_SCHEDULER_ENABLE_VERBOSITY
printf("scheduling_class:%s ",
THORIUM_CLASS_NORMAL_STRING);
#endif
}
#ifdef THORIUM_SCHEDULER_ENABLE_VERBOSITY
thorium_worker_print_actors(worker, self);
#endif
}
core_vector_sort_int_reverse(&burdened_workers);
core_vector_sort_int(&stalled_workers);
stalled_count = core_vector_size(&stalled_workers);
#ifdef THORIUM_SCHEDULER_ENABLE_VERBOSITY
printf("MIGRATIONS (stalled: %d, burdened: %d)\n", (int)core_vector_size(&stalled_workers),
(int)core_vector_size(&burdened_workers));
#endif
stalled_index = 0;
core_vector_iterator_init(&vector_iterator, &burdened_workers);
while (stalled_count > 0
&& core_vector_iterator_get_next_value(&vector_iterator, &pair)) {
old_worker = core_pair_get_second(&pair);
worker = thorium_worker_pool_get_worker(self->pool, old_worker);
set = thorium_worker_get_actors(worker);
/*
thorium_worker_print_actors(worker);
printf("\n");
*/
/*
* Lock the worker and try to select actors for migration
*/
core_map_iterator_init(&set_iterator, set);
maximum = -1;
with_maximum = 0;
total = 0;
with_messages = 0;
while (core_map_iterator_get_next_key_and_value(&set_iterator, &actor_name, NULL)) {
actor = thorium_node_get_actor_from_name(thorium_worker_pool_get_node(self->pool), actor_name);
messages = thorium_balancer_get_actor_production(self, actor);
if (maximum == -1 || messages > maximum) {
maximum = messages;
with_maximum = 1;
} else if (messages == maximum) {
with_maximum++;
}
if (messages > 0) {
++with_messages;
}
total += messages;
}
core_map_iterator_destroy(&set_iterator);
core_map_iterator_init(&set_iterator, set);
--with_maximum;
candidates = 0;
load_value = thorium_worker_get_scheduling_epoch_load(worker) * SCHEDULER_PRECISION;
remaining_load = load_value;
#if 0
printf("maximum %d with_maximum %d\n", maximum, with_maximum);
#endif
while (core_map_iterator_get_next_key_and_value(&set_iterator, &actor_name, NULL)) {
actor = thorium_node_get_actor_from_name(thorium_worker_pool_get_node(self->pool), actor_name);
if (actor == NULL) {
continue;
}
messages = thorium_balancer_get_actor_production(self, actor);
#ifdef THORIUM_SCHEDULER_ENABLE_SYMMETRIC_SCHEDULING
script = thorium_actor_script(actor);
/* symmetric actors are migrated elsewhere.
*/
if (core_map_get_value(&symmetric_actor_scripts, &script, NULL)) {
continue;
}
#endif
/* Simulate the remaining load
*/
projected_load = remaining_load;
projected_load -= ((0.0 + messages) / total) * load_value;
#ifdef THORIUM_SCHEDULER_DEBUG
printf(" TESTING actor %d, production was %d, projected_load is %d (- %d * (1 - %d/%d)\n",
actor_name, messages, projected_load,
load_value, messages, total);
#endif
/* An actor without any queued messages should not be migrated
*/
if (messages > 0
&& ((with_maximum > 0 && messages == maximum) || messages < maximum)
/*
* Avoid removing too many actors because
* generating a stalled one is not desired
*/
&& (projected_load >= load_percentile_50
/*
* The previous rule does not apply when there
* are 2 actors.
*/
|| with_messages == 2) ) {
remaining_load = projected_load;
candidates++;
if (messages == maximum) {
--with_maximum;
}
core_pair_init(&pair, messages, actor_name);
core_vector_push_back(&actors_to_migrate, &pair);
#ifdef THORIUM_SCHEDULER_DEBUG
printf("early CANDIDATE for migration: actor %d, worker %d\n",
actor_name, old_worker);
#endif
}
}
core_map_iterator_destroy(&set_iterator);
}
core_vector_iterator_destroy(&vector_iterator);
/* Sort the candidates
*/
/*
core_vector_sort_int(&actors_to_migrate);
printf("Percentiles for production: ");
core_statistics_print_percentiles_int(&actors_to_migrate);
*/
/* Sort them in reverse order.
*/
core_vector_sort_int_reverse(&actors_to_migrate);
core_vector_iterator_init(&vector_iterator, &actors_to_migrate);
/* For each highly active actor,
* try to match it with a stalled worker
*/
while (core_vector_iterator_get_next_value(&vector_iterator, &pair)) {
actor_name = core_pair_get_second(&pair);
actor = thorium_node_get_actor_from_name(thorium_worker_pool_get_node(self->pool), actor_name);
if (actor == NULL) {
continue;
}
messages = thorium_balancer_get_actor_production(self, actor);
old_worker = thorium_actor_assigned_worker(actor);
worker = thorium_worker_pool_get_worker(self->pool, old_worker);
/* old_total can not be 0 because otherwise the would not
* be burdened.
*/
old_total = thorium_worker_get_production(worker, self);
with_messages = thorium_worker_get_producer_count(worker, self);
old_load = thorium_worker_get_scheduling_epoch_load(worker) * SCHEDULER_PRECISION;
actor_load = ((0.0 + messages) / old_total) * old_load;
/* Try to find a stalled worker that can take it.
*/
test_stalled_index = stalled_index;
tests = 0;
predicted_new_load = 0;
found_match = 0;
while (tests < stalled_count) {
core_vector_get_value(&stalled_workers, test_stalled_index, &pair);
new_worker_index = core_pair_get_second(&pair);
new_worker = thorium_worker_pool_get_worker(self->pool, new_worker_index);
new_load = thorium_worker_get_scheduling_epoch_load(new_worker) * SCHEDULER_PRECISION;
/*new_total = thorium_worker_get_production(new_worker);*/
predicted_new_load = new_load + actor_load;
if (predicted_new_load > SCHEDULER_PRECISION /* && with_messages != 2 */) {
#ifdef THORIUM_SCHEDULER_DEBUG
printf("Scheduler: skipping actor %d, predicted load is %d >= 100\n",
actor_name, predicted_new_load);
#endif
++tests;
++test_stalled_index;
if (test_stalled_index == stalled_count) {
test_stalled_index = 0;
}
continue;
}
/* Otherwise, this stalled worker is fine...
*/
stalled_index = test_stalled_index;
found_match = 1;
break;
}
/* This actor can not be migrated to any stalled worker.
*/
if (!found_match) {
continue;
}
/* Otherwise, update the load of the stalled one and go forward with the change.
*/
pair_pointer = (struct core_pair *)core_vector_at(&stalled_workers, stalled_index);
core_pair_set_first(pair_pointer, predicted_new_load);
++stalled_index;
if (stalled_index == stalled_count) {
stalled_index = 0;
}
#if 0
new_worker = thorium_worker_pool_get_worker(pool, new_worker_index);
printf(" CANDIDATE: actor %d old worker %d (%d - %d = %d) new worker %d (%d + %d = %d)\n",
actor_name,
old_worker, value, messages, 2new_score,
new_worker_index, new_worker_old_score, messages, new_worker_new_score);
#endif
thorium_migration_init(&migration, actor_name, old_worker, new_worker_index);
core_vector_push_back(&migrations, &migration);
thorium_migration_destroy(&migration);
}
core_vector_iterator_destroy(&vector_iterator);
core_vector_destroy(&stalled_workers);
core_vector_destroy(&burdened_workers);
core_vector_destroy(&loads);
core_vector_destroy(&loads_unsorted);
core_vector_destroy(&actors_to_migrate);
/* Update the last values
*/
for (i = 0; i < thorium_worker_pool_worker_count(self->pool); i++) {
worker = thorium_worker_pool_get_worker(self->pool, i);
set = thorium_worker_get_actors(worker);
core_map_iterator_init(&set_iterator, set);
while (core_map_iterator_get_next_key_and_value(&set_iterator, &actor_name, NULL)) {
actor = thorium_node_get_actor_from_name(thorium_worker_pool_get_node(self->pool), actor_name);
thorium_balancer_update_actor_production(self, actor);
}
core_map_iterator_destroy(&set_iterator);
thorium_worker_reset_scheduling_epoch(worker);
}
#ifdef THORIUM_SCHEDULER_ENABLE_SYMMETRIC_SCHEDULING
/* Generate migrations for symmetric actors.
*/
thorium_balancer_generate_symmetric_migrations(self, &symmetric_actor_scripts, &migrations);
#endif
/* Actually do the migrations
*/
core_vector_iterator_init(&vector_iterator, &migrations);
while (core_vector_iterator_next(&vector_iterator, (void **)&migration_to_do)) {
thorium_balancer_migrate(self, migration_to_do);
}
core_vector_iterator_destroy(&vector_iterator);
self->last_migrations = core_vector_size(&migrations);
core_vector_destroy(&migrations);
#ifdef THORIUM_WORKER_ENABLE_LOCK
/* Unlock all workers
*/
for (i = 0; i < thorium_worker_pool_worker_count(self->pool); i++) {
worker = thorium_worker_pool_get_worker(self->pool, i);
thorium_worker_unlock(worker);
}
#endif
#ifdef THORIUM_SCHEDULER_ENABLE_SYMMETRIC_SCHEDULING
core_map_destroy(&symmetric_actor_scripts);
#endif
core_timer_stop(&timer);
printf("SCHEDULER: elapsed time for balancing: %d us, %d migrations performed\n",
(int)(core_timer_get_elapsed_nanoseconds(&timer) / 1000),
self->last_migrations);
}
