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Spike in CPU usage when iterating over large 'body' object with long timeout.

See original GitHub issue

Current behavior:

Cypress interactive mode is trying things out with long timeouts.

CPU usage goes high and computer becomes warm.

Assumptions: Therefore doing too much on my CPU and network and therefore networks turns off.

https://youtu.be/IIpUElTV1Sk (Unlisted video, only you can see it)

When I kill the Cypress process, wifi turns on by itself.

Desired behavior:

Cypress does handle long timeouts.

It does not overflow the system and therefore does not overuse CPU and network, so that nothing turns itself off.

Test code to reproduce

Versions

MacOS 10.15.3

“cypress-cucumber-preprocessor”: “^2.0.1”, “cypress”: “^4.2.0”,

The timeout length is intentionally set:

{
  "testFiles": "**/*.feature",
  "chromeWebSecurity": false,
  "defaultCommandTimeout": 60000,
  "video": true
}

Issue Analytics

State:
Created 3 years ago
Comments:5 (3 by maintainers)

Top GitHub Comments

1reaction

jennifer-shehanecommented, Apr 9, 2020

Setting numTestsKeptInMemory: 0 in the cypress.json may help reduce the CPU usage. I’d suggest doing that to help for now.

I think this is due to a few lines in your test, where you are wrapping over the entire body of an iframe and asserting against the body, with the increasing timeout making the issue worse.

There shouldn’t be a reason to have the commandTimeout : 60000 for this specific .find() command (since you already have the body object, retrying will not change the Object value) - and I’d suggest overwriting it with a lower timeout as a current workaround.

I can recreate a spike in CPU using the following code:

index.html

<!DOCTYPE html>
<html>
<body>
  <iframe src="iframe.html"></iframe>
</body>
</html>

iframe.html

// basically some very large HTML

it("visit example", () => {
  cy.visit("index.html")
  cy.get("iframe")
    .its("0.contentDocument.body").should("not.be.empty")
    .then(cy.wrap)
     // increase timeout to see issue
    .find(".wishlist h6", { timeout: 60000 }) 
    .should("be.visible")
})

Without `{ timeout: 60000 }`

Screen Shot 2020-04-09 at 5 27 43 PM

With `{ timeout: 60000 }`

Screen Shot 2020-04-09 at 5 30 38 PM

Seems to be spending a lot of time on this formatProperty method.

https://github.com/cypress-io/cypress/blob/develop/packages/driver/src/cy/chai/inspect.js#L314:L314

0reactions

BlueWindscommented, Dec 21, 2021

This seems closely related to a bug fixed in 9,2, where unnecessary snapshots were being created while retrying commands. In some browsers this manifested as a memory leak followed by the browser crashing or hanging, while in others in caused an unnecessarily large amount of CPU usage, scaling with the size of the page under test.

https://github.com/cypress-io/cypress/issues/18549

A more technical discussion of the causes and resolution of the issue can be found in the PR that closed it: https://github.com/cypress-io/cypress/pull/19311

I’m going close this issue as resolved in 9.2,0 - if anyone involved is still seeing it after updating to that release, please let me know and I’ll reopen.

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