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terminate photon task dispatch early when workers or resources are unavailable #311

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Merged
merged 2 commits into from
Feb 23, 2017
Merged

terminate photon task dispatch early when workers or resources are unavailable #311

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terminate photon task dispatch early when no workers or resources ava…
atumanov Feb 23, 2017
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atumanov Feb 23, 2017
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42 changes: 27 additions & 15 deletions src/photon/photon_algorithm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -572,8 +572,31 @@ void dispatch_tasks(local_scheduler_state *state,

/* Assign as many tasks as we can, while there are workers available. */
DL_FOREACH_SAFE(algorithm_state->dispatch_task_queue, elt, tmp) {
/* TODO(atumanov): as an optimization, we can also check if all dynamic
* capacity is zero and bail early. */
/* If there is a task to assign, but there are no more available workers in
* the worker pool, then exit. Ensure that there will be an available
* worker during a future invocation of dispatch_tasks. */
if (utarray_len(algorithm_state->available_workers) == 0) {
if (utarray_len(state->child_pids) == 0) {
/* If there are no workers, including those pending PID registration,
* then we must start a new one to replenish the worker pool. */
start_worker(state, NIL_ACTOR_ID);
}
return;
}
/* Terminate early if there are no more resources available. */
bool resources_available = false;
for (int i = 0; i < MAX_RESOURCE_INDEX; i++) {
if (state->dynamic_resources[i] > 0) {
/* There are still resources left, continue checking tasks. */
resources_available = true;
break;
}
}
if (!resources_available) {
/* No resources available -- terminate early. */
return;
}
/* Skip to the next task if this task cannot currently be satisfied. */
bool task_satisfied = true;
for (int i = 0; i < MAX_RESOURCE_INDEX; i++) {
if (task_spec_get_required_resource(elt->spec, i) >
Expand All @@ -584,19 +607,8 @@ void dispatch_tasks(local_scheduler_state *state,
}
}
if (!task_satisfied) {
continue; /* Proceed to the next task. */
}

/* If there is a task to assign, but there are no more available workers in
* the worker pool, then exit. Ensure that there will be an available
* worker during a future invocation of dispatch_tasks. */
if (utarray_len(algorithm_state->available_workers) == 0) {
if (utarray_len(state->child_pids) == 0) {
/* If there are no workers, including those pending PID registration,
* then we must start a new one to replenish the worker pool. */
start_worker(state, NIL_ACTOR_ID);
}
break;
/* This task could not be satisfied -- proceed to the next task. */
continue;
}

/* Dispatch this task to an available worker and dequeue the task. */
Expand Down