High CPU Usage Even When Not Automating UI

Current behavior:

When running our test suite we have a number of before hooks that perform some setup making use of cy.request A LOT.

When our tests run we experience super high CPU usage even when not automating the UI (performing the requests). My machine is no slouch but cypress utilises all 4 cores for a http request, this behaviour seems very odd.

I am only running cypress, chrome and a music player. Even if I shut down all other apps cypress is very greedy.

Desired behavior:

Cypress should not use 100% CPU for performing a HTTP request when the automation is idle.

Test code to reproduce

// the reason we do this chaining is to store the complete output into an object (a string array in this case but that's just for example)
// rather than using some static global
function lotsOfApi(): Cypress.Chainable<string[]> {
  let chain: Cypress.Chainable<null | Cypress.Response> = cy.wrap(null);
  const testData: string[] = [];
  for (let i = 0; i < 1000; i++) {
    chain = chain.then(() => {
      return cy.request('https://dummyapi.io/data/api/user').then((response) => {
        // store some values from response
        testData.push(response.statusText);
      });
    });
  }
  return chain.then(() => testData);
}

describe('lots of api tests', () => {

  let testData: string[] | null = null;

  before(() => lotsOfApi().then((d) => (testData = d)));

  it('should have data', () => assert.isArray(testData));

});

Versions

Cypress: v4.12.1 OS: Windows 10 Browser: Electron (or chrome)

[shwarcu]

Performance issues in Cypress is something quite common. In my case on Macbook Pro 16 with 32GB of ram, after running a suite of tests I can barely select commands in the preview and see snapshots of the page from that point of time. It takes a lot of time for Cypress to update view of test runner. It’s very very slow, sometimes unusable.

I have run your code, result was identical. Cypress processes entirely occupied CPU and my mac started to heat up. I will try to run this snipped at home with Ryzen 2700X and see if Cypress will also consume entire cpu with this task.

[rajutandukar]

i am also having same issue . i use macOs 2GHz core intel core i5, 16GB. Cypress get hung and have to force quit even nothing were ran.