antigravity-skills-reference/skills/dbos-python/references/queue-basics.md

title, impact, impactDescription, tags

title	impact	impactDescription	tags
Use Queues for Concurrent Workflows	HIGH	Queues provide managed concurrency and flow control	queue, concurrency, enqueue, workflow

Use Queues for Concurrent Workflows

Queues run many workflows concurrently with managed flow control. Use them when you need to control how many workflows run at once.

Incorrect (uncontrolled concurrency):

@DBOS.workflow()
def process_task(task):
    pass

# Starting many workflows without control
for task in tasks:
    DBOS.start_workflow(process_task, task)  # Could overwhelm resources

Correct (using queue):

from dbos import Queue

queue = Queue("task_queue")

@DBOS.workflow()
def process_task(task):
    pass

@DBOS.workflow()
def process_all_tasks(tasks):
    handles = []
    for task in tasks:
        # Queue manages concurrency
        handle = queue.enqueue(process_task, task)
        handles.append(handle)
    # Wait for all tasks
    return [h.get_result() for h in handles]

Queues process workflows in FIFO order. You can enqueue both workflows and steps.

queue = Queue("example_queue")

@DBOS.step()
def my_step(data):
    return process(data)

# Enqueue a step
handle = queue.enqueue(my_step, data)
result = handle.get_result()

Reference: DBOS Queues