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Reduce unnecessary task stickiness #49601

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Merged
merged 2 commits into from
May 6, 2023
Merged

Reduce unnecessary task stickiness #49601

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e95416f
Close channel task doesn't need to be sticky
kpamnany May 1, 2023
9dbfc05
Set task tid before scheduling task in `_wait2`
kpamnany May 3, 2023
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1 change: 1 addition & 0 deletions base/channels.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -253,6 +253,7 @@ Stacktrace:
"""
function bind(c::Channel, task::Task)
T = Task(() -> close_chnl_on_taskdone(task, c))
T.sticky = false
_wait2(task, T)
return c
end
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24 changes: 12 additions & 12 deletions base/task.jl
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Expand Up @@ -317,22 +317,22 @@ end
# have `waiter` wait for `t`
function _wait2(t::Task, waiter::Task)
if !istaskdone(t)
# since _wait2 is similar to schedule, we should observe the sticky
# bit, even if we don't call `schedule` with early-return below
if waiter.sticky && Threads.threadid(waiter) == 0 && !GC.in_finalizer()
# Issue #41324
# t.sticky && tid == 0 is a task that needs to be co-scheduled with
# the parent task. If the parent (current_task) is not sticky we must
# set it to be sticky.
# XXX: Ideally we would be able to unset this
current_task().sticky = true
tid = Threads.threadid()
ccall(:jl_set_task_tid, Cint, (Any, Cint), waiter, tid-1)
end
lock(t.donenotify)
if !istaskdone(t)
push!(t.donenotify.waitq, waiter)
unlock(t.donenotify)
# since _wait2 is similar to schedule, we should observe the sticky
# bit, even if we aren't calling `schedule` due to this early-return
if waiter.sticky && Threads.threadid(waiter) == 0 && !GC.in_finalizer()
# Issue #41324
# t.sticky && tid == 0 is a task that needs to be co-scheduled with
# the parent task. If the parent (current_task) is not sticky we must
# set it to be sticky.
# XXX: Ideally we would be able to unset this
current_task().sticky = true
tid = Threads.threadid()
ccall(:jl_set_task_tid, Cint, (Any, Cint), waiter, tid-1)
end
return nothing
else
unlock(t.donenotify)
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