Make GC smarter #17919
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Make GC smarter #17919
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190n
requested changes
Mar 5, 2025
| @@ -886,7 +887,7 @@ pub const VirtualMachine = struct { | |||
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| module_loader: ModuleLoader = .{}, | |||
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| gc_controller: JSC.GarbageCollectionController = .{}, | |||
| gc_controller: *GCController = undefined, | |||
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| // Check allocation rate (is memory growing rapidly?) | ||
| bool rapidMemoryGrowth = m_lastBlockBytesAllocated > 0 && (currentHeapSize > m_lastBlockBytesAllocated * 1.5); |
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How frequently does this run? If it's very frequent then a ratio smaller than 1.5 might make sense.
190n
requested changes
Mar 5, 2025
190n
reviewed
Mar 5, 2025
| return Bun__isBusyDoingImportantWork(bunVM); | ||
| } | ||
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| bool BunGCController::checkMemoryPressure() const |
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Could this respond to memory pressure notifications from the system?
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Test failures also seem new/relevant |
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What does this PR do?
This PR implements a new garbage collection controller, improving coordination between JavaScriptCore's GC and the event loop.
The previous implementation used a timer-based approach that didn't account for application activity and was separate from JSC's timer-based GC mechanism. The new controller is more intelligent, deferring collection while HTTP requests are ongoing. It also detects when 70% or more RSS is in use while a full collection is in progress and attempts to aggressively free more memory.
How did you verify your code works?