<@ULVA73B9P> i’m not sure i understand workpools a...
# ask-marvin
r
@Marvin i’m not sure i understand workpools and workers; so i created a process workpool, and then i started a worker for it; for a process workpool, do I need to start multiple workers? or will the process worker create the subprocesses for me to run the flows? if i only need one process worker for a process workpool then is there a point to setting a concurrency limit on the pool, or should i just put it on the worker
m
In Prefect 3.x, work pools and workers are designed to manage and execute flow runs efficiently. Here's a breakdown of how they work, particularly focusing on process work pools and workers: 1. Process Work Pools and Workers: - A process work pool is a mechanism to manage and coordinate the execution of flow runs. It acts as a channel to distribute work to workers. - A process worker polls the work pool for new runs and executes them as subprocesses. This means that a single process worker can indeed handle multiple flow runs by creating subprocesses for each. 2. Concurrency Limits: - You can set concurrency limits on both the work pool and the worker. - Work Pool Concurrency Limit: This restricts the number of concurrent flow runs across all workers polling the pool. It ensures that no more than the specified number of runs are in the
Running
or
Pending
state at any time. - Worker Concurrency Limit: This limits the number of subprocesses a single worker can handle at once. 3. Best Practices: - If you have a single worker and want to control the number of concurrent runs it handles, setting a concurrency limit on the worker might be sufficient. - If you have multiple workers polling the same pool, setting a concurrency limit on the work pool can help manage the overall load across all workers. For more detailed information, you can refer to the Prefect documentation on work pools and workers.
r
@Marvin so for a process type pool, is there a benefit to having multiple workers?
m
For a process-type work pool, having multiple workers can offer several benefits: 1. Load Distribution: Multiple workers can distribute the load of executing flow runs, which can be particularly beneficial if you're running flows that are resource-intensive or if you have a high volume of flow runs. 2. Fault Tolerance: If one worker fails or encounters an issue, other workers can continue processing flow runs, providing a level of redundancy. 3. Scalability: With multiple workers, you can scale out your execution capacity by adding more workers to the pool, allowing you to handle more concurrent flow runs as needed. 4. Geographic Distribution: If your infrastructure is distributed across different geographic locations, having workers in different locations can reduce latency for specific tasks or datasets that are location-dependent. However, if your flows are lightweight and your current single worker setup is handling the load without issues, you might not see immediate benefits from adding more workers. It largely depends on your specific use case and infrastructure requirements.
r
@Marvin they’re all local on the same machine
m
If all your workers are running locally on the same machine, the benefits of having multiple workers for a process-type pool may be limited: 1. Resource Contention: Multiple workers on the same machine will compete for the same CPU and memory resources. If your machine's resources are already fully utilized by a single worker, adding more workers won't necessarily improve performance and might even degrade it. 2. Simplified Management: Managing a single worker is generally simpler. If your machine can handle the desired number of concurrent flow runs with one worker, there's little need to complicate the setup with multiple workers. 3. Single Point of Failure: Running multiple workers doesn't provide additional fault tolerance if they're all on the same machine. A failure affecting the machine will impact all workers equally. In summary, unless you're hitting concurrency limits with a single worker and your machine has the resources to handle more, you might not gain much from running multiple workers locally.