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<@ULVA73B9P> I'm trying to limit execution time of...
# ask-marvin
a
@Marvin I'm trying to limit execution time of a task to three minutes. Before, it worked with the following code
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status = tasks.export_dip.submit(sip_uuid, dip_dir, c).wait(180)

if not status:
m
It looks like you're currently using Prefect to manage your task execution times. Prefect has built-in functionality for handling task timeouts. Here are the instructions according to the version of Prefect you might be using: For Prefect 2.x: To set a timeout on a task in Prefect 2.x, you'll specify a timeout duration directly in your task definition. Here's an example for illustration:
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python
from prefect import task, Flow

@task(timeout_seconds=180)
def export_dip(sip_uuid, dip_dir, c):
    # Your task implementation
    pass

with Flow("example-flow") as flow:
    result = export_dip(sip_uuid, dip_dir, c)

if __name__ == "__main__":
    flow.run()
This setting ensures that if the task runs for more than 180 seconds, it will be terminated. Prefect 2.x Task Documentation For Prefect 3.x: Similarly, in Prefect 3.x, you can also specify a timeout using 
timeout_seconds
in the task definition:
Copy code
python
from prefect import task, flow

@task(timeout_seconds=180)
def export_dip(sip_uuid, dip_dir, c):
    # Your task implementation
    pass

@flow
def example_flow():
    result = export_dip(sip_uuid, dip_dir, c)

if __name__ == "__main__":
    example_flow()
In this version, the task will also raise a timeout exception if it exceeds the specified duration. Prefect 3.x Task Documentation Both examples utilize 
timeout_seconds
to ensure tasks are limited to a three-minute runtime. Adjust your code according to the version you are using. Is this the functionality you're looking for? If you need further assistance or encounter any issues, please let me know!
a
@Marvin I have used timeout_seconds before, but it did not work because the task I executed was unresponsive. That is why I used the wait() method. However, now this method appears to always return None, even if the task I'm running finished in time and has a return value
m
It seems you're experiencing an issue where the 
wait()
method always returns 
None
for your Prefect tasks. Based on the information available, here are a few key points and possible solutions: 1. Issue with 
wait()
Method: This method is designed to block until the task completes or the specified timeout is reached. If it always returns 
None
, it may indicate an underlying issue or misunderstanding in its usage. 2. Alternative Approach - Timeout Handling: Since using 
timeout_seconds
wasn't effective for your unresponsive task, let's consider an alternative approach. You can manage timeouts more reliably by using 
multiprocessing
to run your task, as it provides a way to kill unresponsive tasks. 3. Example with 
multiprocessing
: Here's how you can execute your task with a timeout using `multiprocessing`:
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python
from multiprocessing import Process, Queue
import time

def run_task(q, sip_uuid, dip_dir, c):
    # Your task implementation
    result = "Task completed successfully"
    q.put(result)  # Put the result in the queue

def execute_with_timeout(sip_uuid, dip_dir, c, timeout):
    q = Queue()
    p = Process(target=run_task, args=(q, sip_uuid, dip_dir, c))
    p.start()
    p.join(timeout)
    if p.is_alive():
        p.terminate()
        p.join()
        return None  # Timeout occurred
    return q.get()

# Usage
sip_uuid = "example_uuid"
dip_dir = "example_dir"
c = "example_c"
status = execute_with_timeout(sip_uuid, dip_dir, c, 180)

if status:
    print("Task completed:", status)
else:
    print("Task timed out")
Handling Task Results in Prefect: To integrate this approach with Prefect while leveraging its task management capabilities, you can define a Prefect task that calls the 
execute_with_timeout
function.
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python
from prefect import task, flow

@task
def execute_task_with_timeout(sip_uuid, dip_dir, c):
    return execute_with_timeout(sip_uuid, dip_dir, c, 180)

@flow
def example_flow():
    result = execute_task_with_timeout("example_uuid", "example_dir", "example_c")
    if result:
        print("Task completed:", result)
    else:
        print("Task timed out")

if __name__ == "__main__":
    example_flow()
This approach ensures your task will not hang indefinitely, providing a more robust solution for handling unresponsive tasks. Further Assistance: If you're still facing issues, it could be beneficial to review the Prefect documentation on handling task timeouts and open a GitHub issue for further insights or assistance from the Prefect community. Feel free to ask if you have any more specific questions or need further clarification!
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