AsyncQueue: await dependencies concurrently to avoid priority inversion#57
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A sequentially-awaited list of dependency tasks only propagates a priority escalation to the dependency currently being awaited. The rest stay at their original priority and can starve under load, producing nondeterministic multi-minute hangs in tests that mix self-serializing and non-self-serializing metadata (e.g. a serial task waiting on many concurrent tasks). Replace the sequential await with concurrentForEach so a priority escalation on the running task reaches every dependency at once. Speculative fix for rdar://178006261
This was referenced May 27, 2026
hamishknight
approved these changes
May 27, 2026
owenv
approved these changes
May 27, 2026
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A sequentially-awaited list of dependency tasks only propagates a priority escalation to the dependency currently being awaited. The rest stay at their original priority and can starve under load, producing nondeterministic multi-minute hangs in tests that mix self-serializing and non-self-serializing metadata (e.g. a serial task waiting on many concurrent tasks).
Replace the sequential await with
concurrentForEachso a priority escalation on the running task reaches every dependency at once.Speculative fix for rdar://178006261