Excessive CPU Utilization when using Percy Playwright

[unlikelyzero]

The problem

We are peeling the onion on some percy cli flakiness found on #1065 and noticed that the CPU utilization of the running process is exceeding the resources available on the basic Circle CI Agent.

CPU Utilization with percy exec enabled

This is the exact same test run but with percy exec disabled

Environment

• Node version: 16
• @percy/cli version: 1.7.2
• OS version: ubuntu focal image

Details

We are using a pretty standard percy integration with playwright. It appears that the CPU is pegged at 100% for the majority of the tests. This is after lowering playwright's cpu utilization by:

1. Disabling all diagnostic tooling from playwright (tracefile, screenshot, video, debug mode)
2. Running a single worker and single test at a time.

Debug logs

https://app.circleci.com/pipelines/github/nasa/openmct/13351/workflows/2c27db3f-cdba-44d6-8651-0aadb149f377/jobs/50220/resources

[Robdel12]

👋🏼 Hey @unlikelyzero! I wouldn't define this as excessive given the baseline without Percy is already 50-75% or so CPU utilization. Percy absolutely does push it over the edge though. I would drop your concurrency from the default 10 to maybe 2 or 3. That will make it so there's only 2 or 3 tabs open in asset discovery processing resources. 10 tabs seems to overwhelm the resources that are available in CI.

https://github.com/nasa/openmct/blob/master/e2e/.percy.yml
https://docs.percy.io/docs/cli-configuration#discovery

version: 2
snapshot:
  widths: [1024, 2000]
  min-height: 1440 # px
discovery:
  concurrency: 3

[unlikelyzero]

@Robdel12 I think this is still an issue. This is when I set discovery to 2: