Avoid use of global AtomicLong for ScheduledFutureTask ids #9599
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Motivation Currently a static AtomicLong is used to allocate a unique id whenever a task is scheduled to any event loop. This could be a source of contention if delayed tasks are scheduled at a high frequency and can be easily avoided by having a non-volatile id counter per queue. Modifications - Replace static AtomicLong ScheduledFutureTask#nextTaskId with a long field in AbstractScheduledExecutorService - Set ScheduledFutureTask#id based on this when adding the task to the queue (in event loop) instead of at construction time - Add simple benchmark Result Less contention / cache-miss possibility when scheduling future tasks Before: Benchmark (num) Mode Cnt Score Error Units scheduleLots 100000 thrpt 20 346.008 ± 21.931 ops/s Benchmark (num) Mode Cnt Score Error Units scheduleLots 100000 thrpt 20 654.824 ± 22.064 ops/s
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Can one of the admins verify this patch? |
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@netty-bot test this please |
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@njhill good one! |
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I need to think about how to port this to master in a safe way. For now I created a label "needs_backport" that we can use to mark PR's that need to be ported. Once done we should remove the label |
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@normanmaurer great idea re the label. One nit tho, wouldn't "forward-port" be more accurate? :) |
This was referenced Mar 9, 2021
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This was referenced Mar 18, 2021
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Motivation
Currently the same static
AtomicLongis used to allocate a unique id whenever a task is scheduled to any event loop. This could be a source of contention if delayed tasks are scheduled at a high frequency and can be easily avoided by having a non-volatile id counter per queue.Modifications
static AtomicLong ScheduledFutureTask#nextTaskIdwith alongfield inAbstractScheduledExecutorServiceScheduledFutureTask#idbased on this when adding the task to the queue (in event loop) instead of at construction timeResult
Less contention / cache-miss possibility when scheduling future tasks
Before:
After: