Parallel Test Execution and Concurrency Limits

Control how many QA.tech test cases run in parallel. Set per-environment concurrency limits to protect staging servers or maximize throughput on production.

QA.tech runs independent test cases in parallel so test plans finish faster than running tests one at a time. By default, there is no cap on how many tests can run at once. You can set a Maximum Concurrent Tests limit on each environment when you need to protect shared infrastructure or control load on a target URL.

How Parallel Execution Works

When you trigger a test plan or multi-test run, QA.tech schedules tests based on your dependency graph:

Test relationship	Execution behavior
Independent tests (no dependencies)	Run in parallel, each in its own isolated browser session
Tests in the same dependency chain	Run sequentially within the chain
Tests linked by Wait For	Dependent test waits for output data; chains can still run in parallel

With no concurrency limit configured, QA.tech auto-scales to run many tests at the same time. A test plan with 20 independent three-minute tests can finish in roughly three minutes instead of an hour.

Parallel execution respects test dependencies. Limits control how many tests run at the same time within a single run; they do not change dependency order.

Configure in the Dashboard

Concurrency limits are configured per environment, not per organization or project. Leave Maximum Concurrent Tests empty for unlimited parallel runs, or enter a positive number to cap concurrency for that environment.

1. Open Applications & Envs

   Go to Settings → Applications & Envs and select the application.

2. Edit an environment

   Scroll to Environments, open the hamburger menu on the environment you want to change, and click Edit.

3. Set Maximum Concurrent Tests

   Leave the field empty for unlimited parallel runs, or enter a positive number to limit concurrency.

4. Save

   Click Save to apply the limit to future runs that use that environment.

How Limits Apply During a Run

When a run starts, QA.tech reads the limit from each environment used by tests in that run and applies the most restrictive value:

Run uses Environment A (limit: 10) and Environment B (limit: 5)
→ Effective limit for the run: 5

Scenario	Effective limit
All environments unlimited	No cap; full auto-scaling
One environment set to 5, others unlimited	5
Environment A: 10, Environment B: 3	3 (minimum wins)

Tests that exceed the limit are queued, not skipped. QA.tech delays extra tests and starts them as slots open, so the full test plan still completes.

When to Set a Limit

Use Maximum Concurrent Tests when parallel runs could overwhelm the environment you are testing:

Situation	Suggested approach
Shared staging server with limited capacity	Set a low limit (for example 3 to 5) on the staging environment
Production smoke tests on a live site	Use a conservative limit to avoid traffic spikes
Dedicated preview or load-test environment	Leave unlimited or set a high limit
CI runs against ephemeral preview URLs	Often unlimited; set a limit if your preview host throttles connections

Leave the field empty when you want the fastest possible test plan execution and your infrastructure can handle concurrent load.

Maximize Parallelism Without Overloading

Parallel execution speed depends on how tests are structured:

1. Reduce unnecessary dependencies - Independent tests run at the same time; long dependency chains run one after another. See Test Dependencies.
2. Set limits per environment - Use a lower limit on staging and a higher or unlimited limit on dedicated test environments.
3. Use Resume From for shared login - Reuse browser state within a chain instead of creating many parallel login tests against the same auth endpoint.

For test plan execution patterns and scheduling, see Test Plans and Running Tests.

Frequently Asked Questions

Can I set a concurrency limit for my whole organization or project?

No. Limits are configured per environment under Settings → Applications & Envs. If you need the same cap everywhere, set it on each environment (staging, production, and so on).

Does a limit of 5 mean only five tests ever run?

No. Up to five tests run at the same time for that run. When one finishes, the next queued test starts. The full plan still runs to completion.

Do dependency chains count as one parallel slot?

Each active test uses a slot. Tests in the same chain run one after another, so they typically use one slot at a time for that chain. Independent chains each use their own slots up to your limit.

Can I set the limit via API?

Not today. Maximum Concurrent Tests is configured in the dashboard on each environment. Per-run API overrides support environment URLs and device presets; see Start Run API.

What happens if I leave Maximum Concurrent Tests empty?

The environment has no concurrency cap. QA.tech parallelizes independent tests and scales concurrent agents based on demand.

Related Documentation

• Projects, Applications, Environments - Where environments and URLs are defined
• Test Plans - Group tests and trigger parallel runs
• Test Dependencies - Control order and browser isolation
• Running Tests - Trigger runs from the UI, CI/CD, or schedules