node-red-contrib-semaphore

A Node-RED node for using semaphores.

Install

Run the following command in the root directory of your Node-RED install

npm install node-red-contrib-semaphore

Usage

This node allows you to limit simultaneous usage of resources.

semaphore take node will queue on available capacity of the underlying semaphore. The take node will display as it's status the name, current queue count, and total capacity of the underlying semaphore.

semaphore leave node will free up an available spot for the queue to process the next task.

It's a good idea to use a node-red catch node that will call a semaphore leave in the event that any node between the take and leave should throw an error.

Use with care, it can be easy to set yourself up in a dead lock situation.

Acknowledgements

The node-red-contrib-semaphore uses the following open source software:

• semaphore nodejs semaphore library.