Queue / Task manager

The queue runs a function in the background, possibly on another node, so nobody waits for it. Use it for slow work that need not finish right now, such as generating a PDF.

Use the queue for work a user should not wait for

Large systems need to offload work to other nodes, and doing that by hand is cumbersome. The queue makes it one block.

Generating a PDF is the classic case: it is computationally intensive, and having it ready this instant is not critical enough to keep the user waiting. Create a custom function that generates the PDF and notifies the user by email. Requested inside the same flow, it would delay the user, so a queue item decouples it from the main flow.

queue block

Give the queue block a function to run

Add function_custom_execute_from_queue and choose the function. It runs that function in the background without waiting for it. It may run on another node or thread: the queue abstracts the location away and aims to execute as closely to the specified time as feasible.

Its in-pins set the time (Execute at) and guard against duplicates (unique ID, Debounce). Every in-pin is described in the block documentation.

Queue items are postponed automatically under load

Each license has a limit on how many queue items can execute at once. It lets you build fast, high-performance functions, and keeps the system from congesting with running queue items.

When you create many queue items at once, the system adds a few seconds to the execution time of each item, to distribute the workload more evenly.

Watch queue items in RUAL Studio

Open Queue in the left-side menu of RUAL Studio. It lists the currently executing, scheduled and completed queue items, so you can see whether and when each one ran.

The page is quasi-real-time. Items move between the tables as they progress, with a delay of a few seconds: the data comes from the backend but is not updated live, to keep the system fast.

queue overview

Next steps