soonq 0.4.1

Subprocess-based task queue.

SoonQ

A subprocess-based task queue.

Introduction

SoonQ implements a simple first-in-first-out (FIFO) queue using SQLite. It was created primarily to give a user direct control over running long simulations.

Installation

pip install soonq

Usage

Users must create their own subclass of soonq.BaseTask. Subclasses must define a run() method, which contains the business logic for the task (what we care about). Input arguments to this method are restricted to being serializable via the pickle module.

Running the examples

Example files are included in the examples directory. Clone SoonQ in your desired location.

C:\desired\location>git clone https://github.com/n8jhj/SoonQ.git

Optionally create a virtual environment within this directory. Then navigate into the SoonQ directory and install it, being careful to include the dot.

pip install .

Now run the same command a couple times in a terminal to enqueue two TimerTasks (the source code is in the examples directory):

C:\...\SoonQ>soonq enq TimerTask 3 3
Queued task: 913d56e9-a609-4b84-b937-479a94716527

C:\...\SoonQ>soonq enq TimerTask 3 3
Queued task: da952424-98d9-42e1-8851-91a30924b94b

C:\...\SoonQ>

You'll be able to see the tasks in the queue.

C:\...\SoonQ>soonq view
+--------------------------------------+------------+----------+----------------------------+--------+--------+
|               task_id                | queue_name | position |         published          |  args  | kwargs |
+--------------------------------------+------------+----------+----------------------------+--------+--------+
| da952424-98d9-42e1-8851-91a30924b94b | TimerTask  |    1     | 2021-05-04 14:45:51.749038 | (3, 3) |   {}   |
| 913d56e9-a609-4b84-b937-479a94716527 | TimerTask  |    0     | 2021-05-04 14:45:50.658199 | (3, 3) |   {}   |
+--------------------------------------+------------+----------+----------------------------+--------+--------+

Now begin a worker process.

C:\...\SoonQ>soonq run TimerTask

A separate terminal will spawn to run the worker. In turn, the worker terminal will spawn task terminals as it works. So there are three levels of processes:

1. The master process. Controls workers.
2. The worker process. Runs a single worker. Can spawn tasks.
3. The task process. Runs a single task.

In the task terminal you will see the runtime text:

1/3 Sleeping 3 seconds...
2/3 Sleeping 3 seconds...
3/3 Sleeping 3 seconds...
Slept 9 seconds total.

Meanwhile, the worker terminal will show:

Running task: 913d56e9-a609-4b84-b937-479a94716527
Finished task: 913d56e9-a609-4b84-b937-479a94716527

Running task: da952424-98d9-42e1-8851-91a30924b94b
Finished task: da952424-98d9-42e1-8851-91a30924b94b

With the worker running, more tasks can be enqueued and will be processed as the worker gets to them. You can spawn more workers if you want. Enqueue more TimerTasks and try it out!

To stop all workers working on a certain queue at any time:

C:\...\SoonQ>soonq stop TimerTask

This will have each worker finish its current task and then shut down. If the --terminate or -t option is used, the workers will stop working and shut down immediately.

Etymology

This project is named after my friend Soon-Kyoo, with whom I enjoyed countless bouts of epic ping-pong in college. He goes by "Q".