Omes - a load generator for Temporal

This project is for testing load generation scenarios against Temporal. This is primarily used by the Temporal team to benchmark features and situations. Backwards compatibility may not be maintained.

Why the weird name?

Omes (pronounced oh-mess) is the Hebrew word for "load" (עומס).

Prerequisites

• Go 1.20+
  • protoc and protoc-gen-go must be installed
  • tip: don't worry about the specific versions here; instead, the GitHub action will make a diff available for download that you can use with git apply
• Java 8+
• TypeScript: Node 16+
• Python 3.10+
  • Poetry: poetry install
• .NET

And if you're running the fuzzer (see below)

• Rust

Usage

Define a scenario

Scenarios are defined using plain Go code. They are located in the scenarios folder. There are already multiple defined that can be used.

A scenario must select an Executor. The most common is the KitchenSinkExecutor which is a wrapper on the GenericExecutor specific for executing the Kitchen Sink workflow. The Kitchen Sink workflow accepts actions and is implemented in every worker language.

For example, here is scenarios/workflow_with_single_noop_activity.go:

func init() {
	loadgen.MustRegisterScenario(loadgen.Scenario{
		Description: "Each iteration executes a single workflow with a noop activity.",
		Executor: loadgen.KitchenSinkExecutor{
			WorkflowParams: kitchensink.NewWorkflowParams(kitchensink.NopActionExecuteActivity),
		},
	})
}

NOTE: The file name where the Register function is called, will be used as the name of the scenario.

Scenario Authoring Guidelines

1. Use snake case for scenario file names.
2. Use KitchenSinkExecutor for most basic scenarios, adding common/generic actions as need, but for unique scenarios use GenericExecutor.
3. When using GenericExecutor, use methods of *loadgen.Run in your Execute as much as possible.
4. Liberally add helpers to the loadgen package that will be useful to other scenario authors.

Run scenario with worker - Start a worker, an optional dev server, and run a scenario

During local development it's typically easiest to run both the worker and the scenario together. You can do that like follows. If you want an embedded server rather than one you've already started, pass --embedded-server.

go run ./cmd run-scenario-with-worker --scenario workflow_with_single_noop_activity --language go

Notes:

• Cleanup is not automatically performed here
• Accepts combined flags for run-worker and run-scenario commands

Run a worker for a specific language SDK

go run ./cmd run-worker --scenario workflow_with_single_noop_activity --run-id local-test-run --language go

Notes:

• --embedded-server can be passed here to start an embedded localhost server
• --task-queue-suffix-index-start and --task-queue-suffix-index-end represent an inclusive range for running the worker on multiple task queues. The process will create a worker for every task queue from <task-queue>-<start> through <task-queue>-end. This only applies to multi-task-queue scenarios.

Run a test scenario

go run ./cmd run-scenario --scenario workflow_with_single_noop_activity --run-id local-test-run

Notes:

• Run ID is used to derive ID prefixes and the task queue name, it should be used to start a worker on the correct task queue and by the cleanup script.
• By default the number of iterations or duration is specified in the scenario config. They can be overridden with CLI flags.
• See help output for available flags.

Cleanup after scenario run

go run ./cmd cleanup-scenario --scenario workflow_with_single_noop_activity --run-id local-test-run

Running a specific version of the SDK

The --version flag can be used to specify a version of the SDK to use, it accepts either a version number lik v1.24.0 or you can also pass a local path to use a local SDK version. This is useful while testing unreleased or in-development versions of the SDK.

go run ./cmd run-scenario-with-worker --scenario workflow_with_single_noop_activity --language go --version /path/to/go-sdk

Building and publishing docker images

For example, to build a go worker image using v1.24.0 of the Temporal Go SDK:

go run ./cmd build-worker-image --language go --version v1.24.0

This will produce an image tagged like <current git commit hash>-go-v1.24.0.

Publishing images is typically done via CI, using the push-images command. See the GHA workflows for more.

Throughput stress and Nexus

The throughput_stress scenario (which is currently only available for Golang) can generate Nexus load if the scenario is started with --option nexus-endpoint=my-nexus-endpoint. This doesn't work with the --embedded-server option, and requires the following steps:

1. Allocate a scenario run-id. This determines the scenario's task queue. (we'll use default-run-id in this tutorial).

2. Start a server with nexus enabled (e.g. --http-port 7243 --dynamic-config-value system.enableNexus=true for the dev server).

3. Create your namespace ahead of time. Note that the dev server will automatically create the default namespace unless specified otherwise.

4. Create a nexus endpoint:

   temporal operator nexus endpoint create \
   --name my-nexus-endpoint \
   --target-namespace default \ # Change if needed
   --target-task-queue throughput_stress:default-run-id
   

5. Start the scenario with the given run-id:

go run ./cmd run-scenario-with-worker --scenario throughput_stress --language go --option nexus-endpoint=my-nexus-endpoint --run-id default-run-id

The fuzzer

The fuzzer scenario makes use of the kitchen sink workflow (see below) to exercise a wide range of possible actions. Actions are pre-generated by the kitchen-sink-gen tool, written in Rust, and are some combination of actions provided to the workflow as input, and actions to be run by a client inside the scenario executor.

You can run the fuzzer with new random actions like so:

go run ./cmd run-scenario-with-worker --scenario fuzzer --iterations 1 --language cs

By default, the scenario will spit out a last_fuzz_run.proto binary file containing the generated actions. To re-run the same set of actions, you can pass in such a file like so:

go run ./cmd run-scenario-with-worker --scenario fuzzer --iterations 1 --language cs --option input-file=last_fuzz_run.proto

Or you can run with a specific seed (seeds are printed at the start of the scenario):

go run ./cmd run-scenario-with-worker --scenario fuzzer --iterations 1 --language cs --option seed=131962944538087455

However, the fuzzer is also sensitive to its configuration, and thus the seed will only produce the exact same set of actions if the config has also not changed. Thus you should prefer to save binary files rather than seeds.

Please do collect interesting fuzz cases in the scenarios/fuzz_cases.yaml file. This file currently has seeds, but could also easily reference stored binary files instead.

Design decisions

Kitchen Sink Workflow

The Kitchen Sink workflows accepts a DSL generated by the kitchen-sink-gen Rust tool, allowing us to test a wide variety of scenarios without having to imagine all possible edge cases that could come up in workflows. Input may be saved for regression testing, or hand written for specific cases.

Scenario Failure

A scenario can only fail if an Execute method returns an error, that means the control is fully in the scenario authors's hands. For enforcing a timeout for a scenario, use options like workflow execution timeouts or write a workflow that waits for a signal for a configurable amount of time.

TODO

• Nicer output that includes resource utilization for the worker (when running all-in-one)
• Ruby worker

Fuzzer trophy case

• Python upsert SA with no initial attributes: PR
• Core cancel-before-start on abandon activities: PR
• Core panic on evicting run with buffered tasks: PR
• Out of order replay for local activity + cancel: PR