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pool: fix scaled-down threads still processing tasks #90

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Merged
v01dstar merged 1 commit into from
Apr 21, 2026
Merged

pool: fix scaled-down threads still processing tasks #90

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5 changes: 5 additions & 0 deletions src/pool/spawn.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -329,6 +329,11 @@ impl<T: TaskCell + Send> Local<T> {
if !self.core.mark_sleep() {
return false;
}
// If this thread is above core_thread_count, go to sleep
// without popping so scaled-down threads don't keep working.
if id > self.core.config.core_thread_count.load(Ordering::SeqCst) {

@glorv glorv Apr 15, 2026

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Can you explain the requirement that need to let the thread park immediately instead of trying to drain the tasks in the local queue? I think in most scenario, the difference should be very small.

@mittalrishabh mittalrishabh Apr 15, 2026

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We use the TiKV thread pool auto-scaling feature and observed that under load, TiKV scales down the number of threads — but the yatp pool does not shrink because its threads are occupied draining the queue and unified read pool CPU remains higher than the number of active threads shown by TiKV

return true;
}
task = self.local_queue.pop();
task.is_none()
},
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