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[Bug]: transformFromAstSync leaks memory #13970
Description
💻
- Would you like to work on a fix?
How are you using Babel?
Programmatic API (babel.transform, babel.parse)
Input code
for (let i = 0; i < 1e7; i++) {
ast = babel.transformFromAstSync(ast, src, {
configFile: false,
ast: true,
}).ast;
}
For a complete reproduction, see https://github.com/JLHwung/babel-transform-from-ast-leak
Configuration file name
No response
Configuration
N.A.
Current and expected behavior
Current: The memory usage rises beyond 2GB
Expected: The memory usage should be stable during repetitive transformFromAstSync calls.
Environment
System:
OS: macOS 12.0.1
Binaries:
Node: 17.0.1 - /opt/homebrew/bin/node
Yarn: 1.22.17 - /opt/homebrew/bin/yarn
npm: 8.1.0 - /opt/homebrew/bin/npm
npmPackages:
@babel/core: ^7.16.0 => 7.16.0
Possible solution
No response
Additional context
Found this issue when running jest --detect-leaks in the Babel codebase.
transformFromAstAsync and transformFromAst are also affected.
When switching transformFromAstSync to transformSync, the memory leakage can not be reproduced.
Activity
babel-bot commentedon Nov 16, 2021
Hey @JLHwung! We really appreciate you taking the time to report an issue. The collaborators on this project attempt to help as many people as possible, but we're a limited number of volunteers, so it's possible this won't be addressed swiftly.
If you need any help, or just have general Babel or JavaScript questions, we have a vibrant Slack community that typically always has someone willing to help. You can sign-up here for an invite.
nicolo-ribaudo commentedon Nov 16, 2021
Does it leak if you pass
cloneAST: false?JLHwung commentedon Nov 16, 2021
Nice catch! The leak is gone when
closeInputAstis disabled. However this option is enabled by default.It is likely that after
cloneDeepis performed, the new AST object still contains reference to the old AST object which prevents them from being collected.