mocha: Error object stored on Runnable._trace leaks memory
FYI: In V8, Error objects keep closures alive until the err.stack property is accessed, which prevents collection of the closure (and associated objects) until the Error objects die.
Mocha creates a long-living Error for each Runnable: https://github.com/mochajs/mocha/blob/2303c669ef1b47fef7cf86f5ef486d537033d443/lib/runnable.js#L56.
Would it make sense to either 1. store a string message instead of an Error, or 2. clear Error.stack, or 3. format Error.stack eagerly instead?
See also: https://crbug.com/v8/7142 and https://twitter.com/wSokra/status/935790750188625920.
About this issue
- Original URL
- State: closed
- Created 7 years ago
- Comments: 17 (10 by maintainers)
Commits related to this issue
- fix memory leak when run in v8; closes #3119 - this means "multiple calls to done" will once again fail to produce a stack trace in the case that those multiple calls happen in separate tasks. - howe... — committed to mochajs/mocha by boneskull 6 years ago
- fix memory leak when run in v8; closes #3119 - this means "multiple calls to done" will once again fail to produce a stack trace in the case that those multiple calls happen in separate tasks. - howe... — committed to mochajs/mocha by boneskull 6 years ago
- fix memory leak when run in v8; closes #3119 - this means "multiple calls to done" will once again fail to produce a stack trace in the case that those multiple calls happen in separate tasks. - howe... — committed to TwineHealth/mocha by boneskull 6 years ago
@HarrySarson Not a bad idea, but it’s also kind of an obscure thing to add a command-line flag for. AFAIK this also affects browser (Chrome) users.
I think I’d like to just rip it out for now and see how it goes.