Priority & Fairness Demo

Interactive demo of Temporal's task queue priority and fairness features using a Streamlit dashboard.

Prerequisites

• Python 3.12+
• uv
• Temporal CLI

Setup

uv sync

Running

1. Start the Temporal dev server

Priority and fairness require specific dynamic config flags:

temporal server start-dev \
    --dynamic-config-value matching.useNewMatcher=true \
    --dynamic-config-value matching.enableFairness=true \
    --dynamic-config-value matching.numTaskqueueReadPartitions=1 \
    --dynamic-config-value matching.numTaskqueueWritePartitions=1

2. Start the worker

unset TEMPORAL_PROFILE
uv run python worker.py

3. Start the dashboard

unset TEMPORAL_PROFILE
uv run streamlit run dashboard.py

unset TEMPORAL_PROFILE ensures you connect to the local dev server instead of Temporal Cloud.

What it does

The dashboard has two tabs:

Priority — Start a batch of workflows with random priorities (P1 High, P3 Medium, P5 Low). With priority enabled, high priority workflows execute before low priority ones. Toggle priority off to see FIFO behavior.

Fairness — Start a batch of workflows split across three tenants (Big 60%, Mid 25%, Small 15%). With fairness enabled, all tenants get regular turns. Toggle fairness off to see the "noisy neighbor" problem where the big tenant starves the others.

The worker is constrained to max_concurrent_activities=1 to force a backlog and make the ordering effects visible.