-
Notifications
You must be signed in to change notification settings - Fork 0
/
runtime.jl
484 lines (445 loc) · 15.8 KB
/
runtime.jl
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
const ConcreteScheduler = Union{WorkStealingScheduler,PrioritizedScheduler}
const ConcreteThunk = Thunk{ConcreteScheduler}
function create_workers(threadids::AbstractVector{<:Integer}, schedulerref::Ref)
return map(threadids) do threadid
t = @task try
eventloop(schedulerref[])
catch err
@error(
"Unexpected error from `eventloop($(schedulerref[]))`",
exception = (err, catch_backtrace())
)
close(schedulerref[])
rethrow()
end
@check 1 <= threadid <= Threads.nthreads()
t.sticky = true
ccall(:jl_set_task_tid, Cvoid, (Any, Cint), t, threadid - 1)
return Worker(t)
end
end
function Schedulers.open(@nospecialize(f), scheduler::AbstractScheduler)
function main()
try
return f(scheduler)
finally
@record(:main_done)
# TODO: wait until scheduler is empty? (i.e., the last worker that
# tried to sleep close the scheduler; it still doesn't wait for the
# "I/O")
close(scheduler)
end
end
@record(:open_register_main, scheduler)
task = generic_task(main, scheduler)
pushat!(scheduler, 1, taskof(task))
run(scheduler)
@check istaskdone(task)
fetch(task)
end
schedulertypeof(::typeof(Schedulers.workstealing)) = WorkStealingScheduler
schedulertypeof(::typeof(Schedulers.prioritized)) = PrioritizedScheduler
(ctx::SchedulerContextFunction)(;
workers::Union{Integer,AbstractVector{<:Integer}} = Threads.nthreads(),
options...,
) = schedulertypeof(ctx)(normalize_threadids(workers); options...)
(ctx::SchedulerContextFunction)(@nospecialize(f); options...) =
Schedulers.open(f, ctx(; options...))
function start(scheduler::AbstractScheduler)
unfair = nothing
for (threadid, worker) in zip(scheduler.threadids, scheduler.workers)
task = taskof(worker)
if threadid == Threads.threadid()
unfair = (; threadid = threadid, task = task)
else
Base.schedule(task)
end
end
if unfair !== nothing
@check unfair.threadid == Threads.threadid()
yield(unfair.task)
end
return scheduler
end
function Base.run(scheduler::AbstractScheduler)
@record(:run_begin, scheduler)
start(scheduler)
waitall(Iterators.map(taskof, scheduler.workers);)
@record(:run_end, scheduler)
return
end
function normalize_threadids(workers::Integer)
@argcheck 1 <= workers <= Threads.nthreads()
return collect(1:Int(workers))
end
function normalize_threadids(workers::AbstractVector{<:Integer})
@argcheck !isempty(workers)
threadids = Int[]
invalids = nothing
for (i, n) in pairs(workers)
if 1 <= n <= Threads.nthreads()
push!(threadids, n)
else
invalids = @something(invalids, Pair{Int,Int}[])
push!(invalids, i => n)
end
end
if invalids === nothing
sort!(threadids)
dups = duplicated_items_in_sorted_iterable(threadids)
if dups === nothing
return threadids
end
error(str, "Duplicated worker IDs: ", join(dups, ", "))
end
str = sprint(invalids) do io, invalids
print(io, "Invalid worker IDs (must be `0 < _ ≤ nthreads = ")
print(io, Threads.nthreads())
print(io, "`): ")
join(io, ("$n ($i-th element)" for (i, n) in invalids), ", ")
end
error(str)
end
struct RescheduleRequest end
# struct WakeupRequest end
struct YieldRequest end
struct WaitRequest end
struct ReturnRequest end
struct ExceptionRequest end
function eventloop(scheduler::AbstractScheduler)
@record(:eventloop_begin, scheduler)
threadid = Threads.threadid()
worker = scheduler.workers[scheduler.workerindices[Threads.threadid()]]
@check current_task() === taskof(worker)
@atomic worker.state = WorkerStates.ACTIVE
unfairspins = max(0, scheduler.unfairspins)
yieldspins = unfairspins + max(0, scheduler.yieldspins)
nspins = 0
while true # task execution loop
@record(:try_get_next_task, scheduler, nspins)
task::Union{Task,Nothing} = get_next_task!(scheduler, nspins > 0)
if task === nothing
@record(:no_next_task, scheduler)
else
@record(:got_next_task, scheduler, task = Historic.taskid(task))
@DBG schedulerof(task) === scheduler
end
if task === nothing
if !isopen(scheduler)
@atomic worker.state = WorkerStates.DONE
break
end
nspins += 1
if nspins < unfairspins
pause()
continue
elseif nspins < yieldspins
yield()
continue
else
@DBG @check worker.state == WorkerStates.ACTIVE
task = trysleep!(scheduler, worker)
if task === nothing
@DBG @check threadid == Threads.threadid()
continue
end
end
end
nspins = 0
# Try to lock the task
_, ok = @atomicreplace(
:acquire_release,
:monotonic,
thunkof(task).worker,
nothing => worker
)
if !ok
push!(scheduler.externalqueue, task)
wakeall!(scheduler)
continue
end
while true # request-reply loop
@DBG @check threadid == Threads.threadid()
@record(:schedule, scheduler, task = Historic.taskid(task))
unset_threadid(task)
@DBG @check Threads.threadid(task) == 0
request = yieldto(task, RescheduleRequest())
@atomic :release thunkof(task).worker = nothing
@record(:requested, scheduler, task = Historic.taskid(task), request)
@DBG @check threadid == Threads.threadid()
if request isa YieldRequest
next = get_next_task!(scheduler, false)
if next isa Task
push!(scheduler, task)
task = next
else
# Nothing in the queue. Re-schedule the `task` that just yielded.
end
elseif request isa WaitRequest
break
elseif request isa Union{ReturnRequest,ExceptionRequest}
if request isa ExceptionRequest
# Let the native scheduler complete the `task`.
# See also `Base.wait(task::GenericTask)`.
yield(task)
end
notifywaiters!(scheduler, task)
break
else
msg = "thread=$threadid: Unexpected request from `yieldto`"
@error msg request
close(scheduler)
errorwith(; scheduler, worker, request) do io, (; request)
print(io, msg)
println(io, ":")
show(io, MIME"text/plain"(), request)
end
end
end # request-reply loop
end # task execution loop
@record(:eventloop_end, scheduler)
end
function (thunk::Thunk)()
try
copy_stack = current_task().sticky
current_task().sticky = true # always sticky wrt the native scheduler
@record(:thunk_begin)
if copy_stack
msg = "Stack-copying not supported"
@error(msg)
error(msg)
end
thunk.state = TaskStates.STARTED
y = thunk.f()
@record(:thunk_returning)
thunk.result = y
thunk.state = TaskStates.DONE
yieldto(taskof(thunk.worker), ReturnRequest())
catch err
# @error(:thunk_error, exception = (err, catch_backtrace()))
@record(:thunk_error, exception = (err, catch_backtrace()))
thunk.result = err
thunk.state = TaskStates.ERROR
yieldto(taskof(thunk.worker), ExceptionRequest())
rethrow()
end
end
function Schedulers.spawn(@nospecialize(f); options...)
scheduler = Schedulers.current_scheduler()
task = generic_task(f, scheduler; options...)
@record(:spawn, task = taskid(task))
schedule!(scheduler, task)
return task
end
function Schedulers.spawn(@nospecialize(f), scheduler::AbstractScheduler; options...)
task = generic_task(f, scheduler; options...)
@record(:spawn_sch, task = taskid(task), scheduler)
schedule!(scheduler, task, scheduler !== Schedulers.current_scheduler())
return task
end
function Schedulers.schedule(task::GenericTask)
scheduler = thunkof(task).scheduler
schedule!(scheduler, task, scheduler !== Schedulers.current_scheduler())
return
end
function schedule!(scheduler, task::Union{Task,GenericTask}, external::AnyBool = FALSE)
task = taskof(task)
isopen(scheduler) || errorwith(; scheduler) do io, data
print(io, "scheduler ", typeof(data.scheduler), " is closed")
end
if boolean(external)
push!(scheduler.externalqueue, task)
else
@DBG @check schedulerof(task) === scheduler
push!(scheduler, task)
end
wakeall!(scheduler)
return
end
function reschedule(task::Union{Task,GenericTask}, current_scheduler)
scheduler = schedulerof(task)
schedule!(scheduler, taskof(task), scheduler !== current_scheduler)
end
function trysleep!(scheduler::AbstractScheduler, worker::Worker)
@atomic worker.state = WorkerStates.PREPARE_WAITING
task::Union{Task,Nothing} = get_next_task!(scheduler, true)
task isa Task && @goto done
state = @atomic :monotonic worker.state
state == WorkerStates.PREPARE_WAITING || @goto done
@record(:worker_wait_cas, scheduler)
@yield_unsafe begin
state, ok = @atomicreplace(
worker.state,
WorkerStates.PREPARE_WAITING => WorkerStates.WAITING
)
ok || @goto done
@record(:worker_wait_begin, scheduler, {yield = false})
end # @yield_unsafe
Base.wait()
@record(:worker_wait_end, scheduler)
@label done
@atomic worker.state = WorkerStates.ACTIVE
return task
end
function wakeall!(scheduler::AbstractScheduler)
for worker in scheduler.workers
state = @atomic worker.state
@record(:wakeall_check, worker_state = state, task = taskid(worker))
while state == WorkerStates.PREPARE_WAITING
state, ok = @atomicreplace(
worker.state,
WorkerStates.PREPARE_WAITING => WorkerStates.NOTIFYING
)
if ok
state = WorkerStates.NOTIFYING
@record(:wakeall_set_notifying, task = taskid(worker))
break
end
end
while state == WorkerStates.WAITING
state, ok =
@atomicreplace(worker.state, WorkerStates.WAITING => WorkerStates.NOTIFYING)
if ok
Base.schedule(worker.task)
@record(:wakeall_scheduled, task = taskid(worker))
state = WorkerStates.NOTIFYING
break
end
end
end
end
Schedulers.yield() = yieldto(scheduler_task(), current_task())::RescheduleRequest
function Schedulers.wait()
@yield_unsafe begin
@record(:wait_begin, waiter_state = thunkof(current_task()).state, {yield = false})
end
yieldto(scheduler_task(), WaitRequest())::RescheduleRequest
@record(:wait_end, waiter_state = thunkof(current_task()).state)
@DBG @check Threads.threadid() == Threads.threadid(scheduler_task())
return
end
function maybe_current_task()
task::Task = current_task()
isdefined(task, :code) || return nothing # root task does not set it
task.code isa ConcreteThunk && return GenericTask(task)
return nothing
end
function Schedulers.current_task()
@return_if_something maybe_current_task()
errorwith(; task = current_task()) do io, (; task)
print(
io,
"Schedulers.current_task() is called from a task not scheduled with \
Schedulers.spawn: ",
task,
)
end
end
function Schedulers.current_scheduler()
task = @something(maybe_current_task(), return nothing)
return thunkof(task).scheduler
end
function trywait(task::GenericTask)
thunk::Thunk = thunkof(task)
head = @atomic thunk.waiter
head isa Closed && return thunk.state
# Register the `current_task()` as a waiter of `task`
waiter = Waiter()
@DBG @check waiter.task === current_task()
@DBG @check waiter.state == WaiterStates.INITIAL
while true
waiter.next = head
(head, ok) = @atomicreplace(thunk.waiter, head => waiter)
head isa Closed && return thunk.state
ok && break
end
@record(:wait_register, node = objid(waiter))
@record(:wait_cas)
# If the CAS is successful, there should be no yield point until
# `Schedulers.wait()` yields.
@yield_unsafe begin
(state, ok) =
@atomicreplace(waiter.state, WaiterStates.INITIAL => WaiterStates.WAITING)
end # @yield_unsafe
if ok
Schedulers.wait()
@check waiter.state == WaiterStates.NOTIFYING
else
@record(:wait_dontwait)
@check state == WaiterStates.DONTWAIT
end
return thunk.state
end
function Base.wait(task::GenericTask)
@record(:wait_task_begin, task = taskid(task))
state = trywait(task)
@record(:wait_task_end, task = taskid(task), task_state = thunkof(task).state, state)
if state == TaskStates.DONE
@record(:wait_done, task = taskid(task))
return
elseif state == TaskStates.ERROR
@record(:wait_error, task = taskid(task))
# throw(thunk.result)
Base.wait(task.task) # use `TaskFailedException` for better stack trace
# Unreachable:
threadid = Threads.threadid()
waiter = current_task()
msg = "thread=$threadid: Unreachable: `wait` did not throw"
@error msg waiter task
errorwith(; threadid, waiter, task) do io, (; waiter, task)
print(io, msg)
print(io, "\n waiter = ", waiter)
print(io, "\n task = ", task)
end
else
error("unreachable: invalid state returned from `trywait`: ", state)
end
end
function notifywaiters!(scheduler::AbstractScheduler, task::Task)
task_state = thunkof(task).state
@record(:notify_begin, task = taskid(task), task_state)
if !isfinished(task_state)
errorwith(; scheduler, task, task_state) do io, (; task, task_state)
print(io, "FATAL: `notifywaiters!` called on an unfinished task")
print(io, "\n task = ", task)
print(io, "\n stateof(task) = ", task_state)
end
end
thunk = thunkof(task)
waiter::Union{Waiter,Nothing} = @atomicswap thunk.waiter = Closed()
while true
waiter === nothing && break
state = @atomic :monotonic waiter.state
@record(
:notify_task,
task = taskid(task),
waiter = taskid(waiter),
node = objid(waiter)
)
while state == WaiterStates.INITIAL
(state, ok) =
@atomicreplace(waiter.state, WaiterStates.INITIAL => WaiterStates.DONTWAIT)
if ok
state = WaiterStates.DONTWAIT
@record(:notify_dontwait, task = taskid(task), waiter = taskid(waiter))
break
end
end
while state == WaiterStates.WAITING
(state, ok) =
@atomicreplace(waiter.state, WaiterStates.WAITING => WaiterStates.NOTIFYING)
if ok
@record(:notify_waking, task = taskid(task), waiter = taskid(waiter))
# TODO: wake the task with `WakeupRequest()`
reschedule(taskof(waiter), scheduler)
break
end
end
waiter = waiter.next
end
@record(:notify_end, task = taskid(task))
end
function Base.fetch(task::GenericTask)
Base.wait(task)
return thunkof(task).result
end