https://bugs.webkit.org/show_bug.cgi?id=151482
Bug ID: 151482
Summary: JSContext Promise resolve tasks too eager, can result
in infinite loop
Classification: Unclassified
Product: WebKit
Version: WebKit Nightly Build
Hardware: Unspecified
OS: Unspecified
Status: NEW
Severity: Normal
Priority: P2
Component: JavaScriptCore
Assignee: webkit-unassigned at lists.webkit.org
Reporter: joepeck at webkit.org
CC: ggaren at apple.com, keith_miller at apple.com,
mark.lam at apple.com, utatane.tea at gmail.com
* SUMMARY
JSContext Promise resolve tasks too eager, can result in infinite loop.
Not sure if we should just treat this as behaves correctly or not. Technically this code does create an infinite loop of "jobs", but it doesn't need to execute in such a 100% hang like it does.
* TEST
JSContext *context = [[JSContext alloc] init];
NSString *script = @""
"function makeAndResolvePromise() {\n"
" Promise.resolve(1).then(function() {\n"
" console.log('resolved');\n"
" makeAndResolvePromise();\n" // Comment out this line to avoid infinite loop.
" });\n"
"};\n"
"makeAndResolvePromise();";
NSLog(@">>> Before");
[context evaluateScript:script];
NSLog(@">>> After"); // Never reached
* NOTES
- Promise.resolve.then will immediately queue a task to run the then callback at the end of this JS event loop (when the VM becomes idle)
- that callback then runs and resolves a promise with a then callback, queued to run at the end of this JS event loop (when the VM becomes idle)
- that callback then runs and resolves a promise with a then callback, queued to run at the end of this JS event loop (when the VM becomes idle)
...
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