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## multi.jl - multiprocessing
##
## julia starts with one process, and processors can be added using:
## addprocs(n) using exec
## addprocs({"host1","host2",...}) using remote execution
##
## remotecall(w, func, args...) -
## tell a worker to call a function on the given arguments.
## returns a RemoteRef to the result.
##
## remote_do(w, f, args...) - remote function call with no result
##
## wait(rr) - wait for a RemoteRef to be finished computing
##
## fetch(rr) - wait for and get the value of a RemoteRef
##
## remotecall_fetch(w, func, args...) - faster fetch(remotecall(...))
##
## pmap(func, lst) -
## call a function on each element of lst (some 1-d thing), in
## parallel.
##
## RemoteRef() - create an uninitialized RemoteRef on the local processor
##
## RemoteRef(p) - ...or on a particular processor
##
## put!(r, val) - store a value to an uninitialized RemoteRef
##
## @spawn expr -
## evaluate expr somewhere. returns a RemoteRef. all variables in expr
## are copied to the remote processor.
##
## @spawnat p expr - @spawn specifying where to run
##
## @async expr -
## run expr as an asynchronous task on the local processor
##
## @parallel (r) for i=1:n ... end -
## parallel loop. the results from each iteration are reduced using (r).
##
## @everywhere expr - run expr everywhere.
# todo:
# * fetch/wait latency seems to be excessive
# * message aggregation
# * timer events
# - send pings at some interval to detect failed/hung machines
# * integrate event loop with other kinds of i/o (non-messages)
# * serializing closures
# * recover from i/o errors
# * handle remote execution errors
# * all-to-all communication
# * distributed GC
# * call&wait and call&fetch combined messages
# * aggregate GC messages
# * dynamically adding nodes (then always start with 1 and grow)
## workers and message i/o ##
function send_msg_unknown(s::IO, kind, args)
error("attempt to send to unknown socket")
end
function send_msg(s::IO, kind, args...)
id = worker_id_from_socket(s)
if id > -1
return send_msg(worker_from_id(id), kind, args...)
end
send_msg_unknown(s, kind, args)
end
function send_msg_now(s::IO, kind, args...)
id = worker_id_from_socket(s)
if id > -1
return send_msg_now(worker_from_id(id), kind, args...)
end
send_msg_unknown(s, kind, args)
end
abstract ClusterManager
type WorkerConfig
# Common fields relevant to all cluster managers
io::Nullable{IO}
host::Nullable{AbstractString}
port::Nullable{Integer}
# Used when launching additional workers at a host
count::Nullable{Union(Int, Symbol)}
exename::Nullable{AbstractString}
exeflags::Nullable{Cmd}
# External cluster managers can use this to store information at a per-worker level
# Can be a dict if multiple fields need to be stored.
userdata::Nullable{Any}
# SSHManager / SSH tunnel connections to workers
tunnel::Nullable{Bool}
bind_addr::Nullable{AbstractString}
sshflags::Nullable{Cmd}
max_parallel::Nullable{Integer}
# Used by Local/SSH managers
connect_at::Nullable{Any}
process::Nullable{Process}
ospid::Nullable{Integer}
# Private dictionary used to store temporary information by Local/SSH managers.
environ::Nullable{Dict}
function WorkerConfig()
wc = new()
for n in fieldnames(WorkerConfig)
T = eltype(fieldtype(WorkerConfig, n))
setfield!(wc, n, Nullable{T}())
end
wc
end
end
type Worker
id::Int
r_stream::AsyncStream
w_stream::AsyncStream
manager::ClusterManager
config::WorkerConfig
del_msgs::Array{Any,1}
add_msgs::Array{Any,1}
gcflag::Bool
Worker(id, r_stream, w_stream, manager, config) =
new(id, r_stream, buffer_writes(w_stream), manager, config, [], [], false)
end
Worker(id, r_stream, w_stream, manager) = Worker(id, r_stream, w_stream, manager, WorkerConfig())
function send_msg_now(w::Worker, kind, args...)
send_msg_(w, kind, args, true)
end
function send_msg(w::Worker, kind, args...)
send_msg_(w, kind, args, false)
end
function flush_gc_msgs(w::Worker)
w.gcflag = false
msgs = copy(w.add_msgs)
if !isempty(msgs)
empty!(w.add_msgs)
remote_do(w, add_clients, msgs...)
end
msgs = copy(w.del_msgs)
if !isempty(msgs)
empty!(w.del_msgs)
#print("sending delete of $msgs\n")
remote_do(w, del_clients, msgs...)
end
end
function send_msg_(w::Worker, kind, args, now::Bool)
#println("Sending msg $kind")
io = w.w_stream
lock(io) do io
serialize(io, kind)
for arg in args
serialize(io, arg)
end
if !now && w.gcflag
flush_gc_msgs(w)
else
flush(io)
end
end
end
function flush_gc_msgs()
for w in (PGRP::ProcessGroup).workers
if isa(w,Worker)
k = w::Worker
if k.gcflag
flush_gc_msgs(k)
end
end
end
end
## process group creation ##
type LocalProcess
id::Int
bind_addr::AbstractString
bind_port::UInt16
LocalProcess() = new(1)
end
const LPROC = LocalProcess()
const map_pid_wrkr = Dict{Int, Union(Worker, LocalProcess)}()
const map_sock_wrkr = ObjectIdDict()
const map_del_wrkr = Set{Int}()
let next_pid = 2 # 1 is reserved for the client (always)
global get_next_pid
function get_next_pid()
retval = next_pid
next_pid += 1
retval
end
end
type ProcessGroup
name::AbstractString
workers::Array{Any,1}
# global references
refs::Dict
ProcessGroup(w::Array{Any,1}) = new("pg-default", w, Dict())
end
const PGRP = ProcessGroup([])
get_bind_addr(pid::Integer) = get_bind_addr(worker_from_id(pid))
get_bind_addr(w::LocalProcess) = LPROC.bind_addr
function get_bind_addr(w::Worker)
if isnull(w.config.bind_addr)
if w.id != myid()
w.config.bind_addr = remotecall_fetch(w.id, get_bind_addr, w.id)
end
end
w.config.bind_addr
end
myid() = LPROC.id
nprocs() = length(PGRP.workers)
function nworkers()
n = nprocs()
n == 1 ? 1 : n-1
end
procs() = Int[x.id for x in PGRP.workers]
function procs(pid::Integer)
if myid() == 1
if (pid == 1) || (isa(map_pid_wrkr[pid].manager, LocalManager))
Int[x.id for x in filter(w -> (w.id==1) || (isa(w.manager, LocalManager)), PGRP.workers)]
else
ipatpid = get_bind_addr(pid)
Int[x.id for x in filter(w -> get_bind_addr(w) == ipatpid, PGRP.workers)]
end
else
remotecall_fetch(1, procs, pid)
end
end
function workers()
allp = procs()
if nprocs() == 1
allp
else
filter(x -> x != 1, allp)
end
end
rmprocset = Set()
function rmprocs(args...; waitfor = 0.0)
# Only pid 1 can add and remove processes
if myid() != 1
error("only process 1 can add and remove processes")
end
global rmprocset
empty!(rmprocset)
for i in vcat(args...)
if i == 1
warn("rmprocs: process 1 not removed")
else
if haskey(map_pid_wrkr, i)
push!(rmprocset, i)
w = map_pid_wrkr[i]
kill(w.manager, i, w.config)
end
end
end
start = time()
while (time() - start) < waitfor
if length(rmprocset) == 0
break;
else
sleep(0.1)
end
end
((waitfor > 0) && (length(rmprocset) > 0)) ? :timed_out : :ok
end
type ProcessExitedException <: Exception end
worker_from_id(i) = worker_from_id(PGRP, i)
function worker_from_id(pg::ProcessGroup, i)
# Processes with pids > ours, have to connect to us. May not have happened. Wait for some time.
if in(i, map_del_wrkr)
throw(ProcessExitedException())
end
if myid()==1 && !haskey(map_pid_wrkr,i)
error("no process with id $i exists")
end
start = time()
while (!haskey(map_pid_wrkr, i) && ((time() - start) < 60.0))
sleep(0.1)
yield()
end
map_pid_wrkr[i]
end
function worker_id_from_socket(s)
w = get(map_sock_wrkr, s, nothing)
if isa(w,Worker)
if is(s, w.r_stream) || is(s, w.w_stream)
return w.id
end
end
if isa(s,IOStream) && fd(s)==-1
# serializing to a local buffer
return myid()
end
return -1
end
register_worker(w) = register_worker(PGRP, w)
function register_worker(pg, w)
push!(pg.workers, w)
map_pid_wrkr[w.id] = w
if isa(w, Worker)
map_sock_wrkr[w.r_stream] = w
map_sock_wrkr[w.w_stream] = w
end
end
deregister_worker(pid) = deregister_worker(PGRP, pid)
function deregister_worker(pg, pid)
pg.workers = filter(x -> !(x.id == pid), pg.workers)
w = pop!(map_pid_wrkr, pid, nothing)
if isa(w, Worker)
pop!(map_sock_wrkr, w.r_stream)
if w.r_stream != w.w_stream
pop!(map_sock_wrkr, w.w_stream)
end
# Notify the cluster manager of this workers death
if myid() == 1
manage(w.manager, w.id, w.config, :deregister)
end
end
push!(map_del_wrkr, pid)
# delete this worker from our RemoteRef client sets
ids = []
tonotify = []
for (id,rv) in pg.refs
if in(pid,rv.clientset)
push!(ids, id)
end
if rv.waitingfor == pid
push!(tonotify, (id,rv))
end
end
for id in ids
del_client(pg, id, pid)
end
# throw exception to tasks waiting for this pid
for (id,rv) in tonotify
notify_error(rv.full, ProcessExitedException())
delete!(pg.refs, id)
end
end
## remote refs ##
const client_refs = WeakKeyDict()
type RemoteRef
where::Int
whence::Int
id::Int
# TODO: cache value if it's fetched, but don't serialize the cached value
function RemoteRef(w, wh, id)
r = new(w,wh,id)
found = getkey(client_refs, r, false)
if !is(found,false)
return found
end
client_refs[r] = true
finalizer(r, send_del_client)
r
end
REQ_ID::Int = 0
function RemoteRef(pid::Integer)
rr = RemoteRef(pid, myid(), REQ_ID)
REQ_ID += 1
if mod(REQ_ID,200) == 0
# force gc after making a lot of refs since they take up
# space on the machine where they're stored, yet the client
# is responsible for freeing them.
gc()
end
rr
end
RemoteRef(w::LocalProcess) = RemoteRef(w.id)
RemoteRef(w::Worker) = RemoteRef(w.id)
RemoteRef() = RemoteRef(myid())
global next_id
next_id() = (id=(myid(),REQ_ID); REQ_ID+=1; id)
end
hash(r::RemoteRef, h::UInt) = hash(r.whence, hash(r.id, h))
==(r::RemoteRef, s::RemoteRef) = (r.whence==s.whence && r.id==s.id)
rr2id(r::RemoteRef) = (r.whence, r.id)
lookup_ref(id) = lookup_ref(PGRP, id)
function lookup_ref(pg, id)
rv = get(pg.refs, id, false)
if rv === false
# first we've heard of this ref
rv = RemoteValue()
pg.refs[id] = rv
push!(rv.clientset, id[1])
end
rv
end
function isready(rr::RemoteRef)
rid = rr2id(rr)
if rr.where == myid()
lookup_ref(rid).done
else
remotecall_fetch(rr.where, id->lookup_ref(id).done, rid)
end
end
del_client(id, client) = del_client(PGRP, id, client)
function del_client(pg, id, client)
rv = lookup_ref(id)
delete!(rv.clientset, client)
if isempty(rv.clientset)
delete!(pg.refs, id)
#print("$(myid()) collected $id\n")
end
nothing
end
function del_clients(pairs::(Any,Any)...)
for p in pairs
del_client(p[1], p[2])
end
end
any_gc_flag = Condition()
function start_gc_msgs_task()
@schedule while true
wait(any_gc_flag)
flush_gc_msgs()
end
end
function send_del_client(rr::RemoteRef)
if rr.where == myid()
del_client(rr2id(rr), myid())
else
if in(rr.where, map_del_wrkr)
# for a removed worker, don't bother
return
end
w = worker_from_id(rr.where)
push!(w.del_msgs, (rr2id(rr), myid()))
w.gcflag = true
notify(any_gc_flag)
end
end
function add_client(id, client)
#println("$(myid()) adding client $client to $id")
rv = lookup_ref(id)
push!(rv.clientset, client)
nothing
end
function add_clients(pairs::(Any,Any)...)
for p in pairs
add_client(p[1], p[2])
end
end
function send_add_client(rr::RemoteRef, i)
if rr.where == myid()
add_client(rr2id(rr), i)
elseif i != rr.where
# don't need to send add_client if the message is already going
# to the processor that owns the remote ref. it will add_client
# itself inside deserialize().
w = worker_from_id(rr.where)
#println("$(myid()) adding $((rr2id(rr), i)) for $(rr.where)")
push!(w.add_msgs, (rr2id(rr), i))
w.gcflag = true
notify(any_gc_flag)
end
end
function serialize(s, rr::RemoteRef)
i = worker_id_from_socket(s)
#println("$(myid()) serializing $rr to $i")
if i != -1
#println("send add $rr to $i")
send_add_client(rr, i)
end
invoke(serialize, (Any, Any), s, rr)
end
function deserialize(s, t::Type{RemoteRef})
rr = invoke(deserialize, (Any, DataType), s, t)
where = rr.where
if where == myid()
add_client(rr2id(rr), myid())
end
# call ctor to make sure this rr gets added to the client_refs table
RemoteRef(where, rr.whence, rr.id)
end
# data stored by the owner of a RemoteRef
type RemoteValue
done::Bool
result
full::Condition # waiting for a value
empty::Condition # waiting for value to be removed
clientset::IntSet
waitingfor::Int # processor we need to hear from to fill this, or 0
RemoteValue() = new(false, nothing, Condition(), Condition(), IntSet(), 0)
end
function work_result(rv::RemoteValue)
v = rv.result
if isa(v,WeakRef)
v = v.value
end
v
end
function wait_full(rv::RemoteValue)
while !rv.done
wait(rv.full)
end
return work_result(rv)
end
function wait_empty(rv::RemoteValue)
while rv.done
wait(rv.empty)
end
return nothing
end
## core messages: do, call, fetch, wait, ref, put! ##
function run_work_thunk(thunk)
local result
try
result = thunk()
catch err
print(STDERR, "exception on ", myid(), ": ")
display_error(err,catch_backtrace())
result = err
end
result
end
function run_work_thunk(rv::RemoteValue, thunk)
put!(rv, run_work_thunk(thunk))
nothing
end
function schedule_call(rid, thunk)
rv = RemoteValue()
(PGRP::ProcessGroup).refs[rid] = rv
push!(rv.clientset, rid[1])
schedule(@task(run_work_thunk(rv,thunk)))
rv
end
#localize_ref(b::Box) = Box(localize_ref(b.contents))
#function localize_ref(r::RemoteRef)
# if r.where == myid()
# fetch(r)
# else
# r
# end
#end
#localize_ref(x) = x
# make a thunk to call f on args in a way that simulates what would happen if
# the function were sent elsewhere
function local_remotecall_thunk(f, args)
if isempty(args)
return f
end
return ()->f(args...)
# TODO: this seems to be capable of causing deadlocks by waiting on
# Refs buried inside the closure that we don't want to wait on yet.
# linfo = ccall(:jl_closure_linfo, Any, (Any,), f)
# if isa(linfo,LambdaStaticData)
# env = ccall(:jl_closure_env, Any, (Any,), f)
# buf = memio()
# serialize(buf, env)
# seek(buf, 0)
# env = deserialize(buf)
# f = ccall(:jl_new_closure, Any, (Ptr{Void}, Any, Any),
# C_NULL, env, linfo)::Function
# end
# f(map(localize_ref,args)...)
end
function remotecall(w::LocalProcess, f, args...)
rr = RemoteRef(w)
schedule_call(rr2id(rr), local_remotecall_thunk(f,args))
rr
end
function remotecall(w::Worker, f, args...)
rr = RemoteRef(w)
#println("$(myid()) asking for $rr")
send_msg(w, :call, rr2id(rr), f, args)
rr
end
remotecall(id::Integer, f, args...) = remotecall(worker_from_id(id), f, args...)
# faster version of fetch(remotecall(...))
function remotecall_fetch(w::LocalProcess, f, args...)
run_work_thunk(local_remotecall_thunk(f,args))
end
function remotecall_fetch(w::Worker, f, args...)
# can be weak, because the program will have no way to refer to the Ref
# itself, it only gets the result.
oid = next_id()
rv = lookup_ref(oid)
rv.waitingfor = w.id
send_msg(w, :call_fetch, oid, f, args)
v = wait_full(rv)
delete!(PGRP.refs, oid)
v
end
remotecall_fetch(id::Integer, f, args...) =
remotecall_fetch(worker_from_id(id), f, args...)
# faster version of wait(remotecall(...))
remotecall_wait(w::LocalProcess, f, args...) = wait(remotecall(w,f,args...))
function remotecall_wait(w::Worker, f, args...)
prid = next_id()
rv = lookup_ref(prid)
rv.waitingfor = w.id
rr = RemoteRef(w)
send_msg(w, :call_wait, rr2id(rr), prid, f, args)
wait_full(rv)
delete!(PGRP.refs, prid)
rr
end
remotecall_wait(id::Integer, f, args...) =
remotecall_wait(worker_from_id(id), f, args...)
function remote_do(w::LocalProcess, f, args...)
# the LocalProcess version just performs in local memory what a worker
# does when it gets a :do message.
# same for other messages on LocalProcess.
thk = local_remotecall_thunk(f, args)
schedule(Task(thk))
nothing
end
function remote_do(w::Worker, f, args...)
send_msg(w, :do, f, args)
nothing
end
remote_do(id::Integer, f, args...) = remote_do(worker_from_id(id), f, args...)
# have the owner of rr call f on it
function call_on_owner(f, rr::RemoteRef, args...)
rid = rr2id(rr)
if rr.where == myid()
f(rid, args...)
else
remotecall_fetch(rr.where, f, rid, args...)
end
end
wait_ref(rid) = (wait_full(lookup_ref(rid)); nothing)
wait(r::RemoteRef) = (call_on_owner(wait_ref, r); r)
fetch_ref(rid) = wait_full(lookup_ref(rid))
fetch(r::RemoteRef) = call_on_owner(fetch_ref, r)
fetch(x::ANY) = x
# storing a value to a Ref
function put!(rv::RemoteValue, val::ANY)
wait_empty(rv)
rv.result = val
rv.done = true
notify_full(rv)
rv
end
put_ref(rid, v) = put!(lookup_ref(rid), v)
put!(rr::RemoteRef, val::ANY) = (call_on_owner(put_ref, rr, val); rr)
function take!(rv::RemoteValue)
wait_full(rv)
val = rv.result
rv.done = false
rv.result = nothing
notify_empty(rv)
val
end
take_ref(rid) = take!(lookup_ref(rid))
take!(rr::RemoteRef) = call_on_owner(take_ref, rr)
function deliver_result(sock::IO, msg, oid, value)
#print("$(myid()) sending result $oid\n")
if is(msg,:call_fetch)
val = value
else
val = oid
end
try
send_msg_now(sock, :result, oid, val)
catch e
# terminate connection in case of serialization error
# otherwise the reading end would hang
print(STDERR, "fatal error on ", myid(), ": ")
display_error(e, catch_backtrace())
wid = worker_id_from_socket(sock)
close(sock)
if myid()==1
rmprocs(wid)
elseif wid == 1
exit(1)
else
remote_do(1, rmprocs, wid)
end
end
end
# notify waiters that a certain job has finished or Ref has been emptied
notify_full (rv::RemoteValue) = notify(rv.full, work_result(rv))
notify_empty(rv::RemoteValue) = notify(rv.empty)
## message event handlers ##
# activity on accept fd
function accept_handler(server::TCPServer, status::Int32)
if status == -1
error("an error occured during the creation of the server")
end
client = accept_nonblock(server)
process_messages(client, client)
end
function process_messages(r_stream::TCPSocket, w_stream::TCPSocket; kwargs...)
@schedule begin
disable_nagle(r_stream)
start_reading(r_stream)
wait_connected(r_stream)
if r_stream != w_stream
disable_nagle(w_stream)
wait_connected(w_stream)
end
create_message_handler_loop(r_stream, w_stream; kwargs...)
end
end
function process_messages(r_stream::AsyncStream, w_stream::AsyncStream; kwargs...)
create_message_handler_loop(r_stream, w_stream; kwargs...)
end
function create_message_handler_loop(r_stream::AsyncStream, w_stream::AsyncStream; ntfy_join_complete=nothing) #returns immediately
@schedule begin
global PGRP
global cluster_manager
try
while true
msg = deserialize(r_stream)
#println("got msg: ",msg)
# handle message
if is(msg, :call)
id = deserialize(r_stream)
#print("$(myid()) got id $id\n")
f0 = deserialize(r_stream)
#print("$(myid()) got call $f0\n")
args0 = deserialize(r_stream)
#print("$(myid()) got args $args0\n")
let f=f0, args=args0
schedule_call(id, ()->f(args...))
end
elseif is(msg, :call_fetch)
id = deserialize(r_stream)
f = deserialize(r_stream)
args = deserialize(r_stream)
let f=f, args=args, id=id, msg=msg
@schedule begin
v = run_work_thunk(()->f(args...))
deliver_result(w_stream, msg, id, v)
v
end
end
elseif is(msg, :call_wait)
id = deserialize(r_stream)
notify_id = deserialize(r_stream)
f = deserialize(r_stream)
args = deserialize(r_stream)
let f=f, args=args, id=id, msg=msg, notify_id=notify_id
@schedule begin
rv = schedule_call(id, ()->f(args...))
deliver_result(w_stream, msg, notify_id, wait_full(rv))
end
end
elseif is(msg, :do)
f = deserialize(r_stream)
args = deserialize(r_stream)
#print("got args: $args\n")
let f=f, args=args
@schedule begin
run_work_thunk(RemoteValue(), ()->f(args...))
end
end
elseif is(msg, :result)
# used to deliver result of wait or fetch
oid = deserialize(r_stream)
#print("$(myid()) got $msg $oid\n")
val = deserialize(r_stream)
put!(lookup_ref(oid), val)
elseif is(msg, :identify_socket)
otherid = deserialize(r_stream)
register_worker(Worker(otherid, r_stream, w_stream, cluster_manager))
elseif is(msg, :join_pgrp)
self_pid = LPROC.id = deserialize(r_stream)
locs = deserialize(r_stream)
self_is_local = deserialize(r_stream)
controller = Worker(1, r_stream, w_stream, cluster_manager)
register_worker(controller)
register_worker(LPROC)
for (connect_at, rpid, r_is_local) in locs
if (rpid < self_pid) && (!(rpid == 1))
# Connect processes with lower pids
wconfig = WorkerConfig()
wconfig.connect_at = connect_at
wconfig.environ = AnyDict(:self_is_local=>self_is_local, :r_is_local=>r_is_local)
(r_s, w_s) = connect(cluster_manager, rpid, wconfig)
w = Worker(rpid, r_s, w_s, cluster_manager, wconfig)
register_worker(w)
process_messages(w.r_stream, w.w_stream)
send_msg_now(w, :identify_socket, self_pid)
else
# Processes with higher pids connect to us. Don't do anything just yet
continue
end
end
send_msg_now(controller, :join_complete, Sys.CPU_CORES, getpid())
elseif is(msg, :join_complete)
w = map_sock_wrkr[r_stream]
environ = get(w.config.environ, Dict())
environ[:cpu_cores] = deserialize(r_stream)
w.config.environ = environ
w.config.ospid = deserialize(r_stream)
put!(ntfy_join_complete, w.id)
ntfy_join_complete = nothing # so that it gets gc'ed
end
end # end of while
catch e
iderr = worker_id_from_socket(r_stream)
# If error occured talking to pid 1, commit harakiri
if iderr == 1
if isopen(w_stream)
print(STDERR, "fatal error on ", myid(), ": ")
display_error(e, catch_backtrace())
end
exit(1)
end
# Will treat any exception as death of node and cleanup
# since currently we do not have a mechanism for workers to reconnect
# to each other on unhandled errors
deregister_worker(iderr)
if isopen(r_stream) close(r_stream) end
if isopen(w_stream) close(w_stream) end
if (myid() == 1)
global rmprocset
if in(iderr, rmprocset)
delete!(rmprocset, iderr)
else
println(STDERR, "Worker $iderr terminated.")
rethrow(e)
end
end
return nothing
end
end
end
function disable_threaded_libs()
blas_set_num_threads(1)
end
## worker creation and setup ##
# The entry point for julia worker processes. does not return. Used for TCP transport.
# Cluster managers implementing their own transport will provide their own.
# Argument is descriptor to write listening port # to.
start_worker() = start_worker(STDOUT)
function start_worker(out::IO)
# we only explicitly monitor worker STDOUT on the console, so redirect
# stderr to stdout so we can see the output.
# at some point we might want some or all worker output to go to log
# files instead.
# Currently disabled since this caused processes to spin instead of
# exit when process 1 shut down. Don't yet know why.
#redirect_stderr(STDOUT)
init_worker()
if LPROC.bind_port == 0
(actual_port,sock) = listenany(uint16(9009))
LPROC.bind_port = actual_port
else
sock = listen(LPROC.bind_port)
end
sock.ccb = accept_handler
print(out, "julia_worker:") # print header
print(out, "$(dec(LPROC.bind_port))#") # print port
print(out, LPROC.bind_addr)
print(out, '\n')
flush(out)
# close STDIN; workers will not use it
#close(STDIN)
disable_nagle(sock)
try
# To prevent hanging processes on remote machines, newly launched workers exit if the
# master process does not connect in time.
# TODO : Make timeout configurable.
check_master_connect(60.0)
while true; wait(); end
catch err
print(STDERR, "unhandled exception on $(myid()): $(err)\nexiting.\n")
end
close(sock)
exit(0)
end
function redirect_worker_output(ident, stream)
@schedule while !eof(stream)
line = readline(stream)
if startswith(line, "\tFrom worker ")
# STDOUT's of "additional" workers started from an initial worker on a host are not available
# on the master directly - they are routed via the initial worker's STDOUT.
print(line)
else
print("\tFrom worker $(ident):\t$line")
end
end
end
# The default TCP transport relies on the worker listening on a free
# port available and printing its bind address and port.
# The master process uses this to connect to the worker and subsequently
# setup a all-to-all network.
function read_worker_host_port(io::IO)
io.line_buffered = true
while true
conninfo = readline(io)
bind_addr, port = parse_connection_info(conninfo)
if bind_addr != ""
return bind_addr, port
end
end
end
function parse_connection_info(str)
m = match(r"^julia_worker:(\d+)#(.*)", str)
if m != nothing
(m.captures[2], parseint(Int16, m.captures[1]))
else
("", int16(-1))
end
end
function init_worker(manager::ClusterManager=DefaultClusterManager())
# On workers, the default cluster manager connects via TCP sockets. Custom
# transports will need to call this function with their own manager.
global cluster_manager
cluster_manager = manager
disable_threaded_libs()
end
# The main function for adding worker processes.
# `manager` is of type ClusterManager. The respective managers are responsible
# for launching the workers. All keyword arguments (plus a few default values)
# are available as a dictionary to the `launch` methods
function addprocs(manager::ClusterManager; kwargs...)
params = merge(default_addprocs_params(), AnyDict(kwargs))
# some libs by default start as many threads as cores which leads to
# inefficient use of cores in a multi-process model.
# Should be a keyword arg?
disable_threaded_libs()
# References to launched workers, filled when each worker is fully initialized and
# has connected to all nodes.
rr_launched = RemoteRef[] # Asynchronously filled by the launch method
start_cluster_workers(manager, params, rr_launched)
# Wait for all workers to be fully connected
sort!([fetch(rr) for rr in rr_launched])
end
default_addprocs_params() = AnyDict(
:dir => pwd(),
:exename => joinpath(JULIA_HOME,julia_exename()),
:exeflags => ``)
function start_cluster_workers(manager, params, rr_launched)
# The `launch` method should add an object of type WorkerConfig for every
# worker launched. It provides information required on how to connect
# to it.
launched = WorkerConfig[]
launch_ntfy = Condition()
# call manager's `launch` is a separate task. This allows the master
# process initiate the connection setup process as and when workers come
# online
t = @schedule try
launch(manager, params, launched, launch_ntfy)
catch e
print(STDERR, "Error launching workers with $(typeof(manager)) : $e\n")
end
# When starting workers on remote multi-core hosts, `launch` can (optionally) start only one
# process on the remote machine, with a request to start additional workers of the
# same type. This is done by setting an appropriate value to `WorkerConfig.cnt`.
workers_with_additional = [] # List of workers with additional on-host workers requested
while true
if length(launched) == 0
if istaskdone(t)
break
end
@schedule (sleep(1); notify(launch_ntfy))
wait(launch_ntfy)
end
if length(launched) > 0
wconfig = shift!(launched)
w = connect_n_create_worker(manager, get_next_pid(), wconfig)
rr = setup_worker(PGRP, w)
cnt = get(w.config.count, 1)
if (cnt == :auto) || (cnt > 1)
push!(workers_with_additional, (w, rr))
end
push!(rr_launched, rr)
end
end
# Perform the launch of additional workers in parallel.
additional_workers = [] # List of workers launched via the "additional" method
@sync begin
for (w, rr) in workers_with_additional
let w=w, rr=rr
@async begin
wait(rr) # :cpu_cores below is set only after we get a setup complete
# message from the new worker.
cnt = get(w.config.count)
if cnt == :auto
cnt = get(w.config.environ)[:cpu_cores]
end
cnt = cnt - 1 # Removing self from the requested number
exename = get(w.config.exename)
exeflags = get(w.config.exeflags, ``)
cmd = `$exename $exeflags`
npids = [get_next_pid() for x in 1:cnt]
new_workers = remotecall_fetch(w.id, launch_additional, cnt, npids, cmd)
push!(additional_workers, (w, new_workers))
end
end
end
end
# connect each of the additional workers with each other
process_additional(additional_workers, rr_launched)
end
function process_additional(additional_workers, rr_launched::Array)
# keyword argument `max_parallel` is only relevant for concurrent ssh connections to a unique host
# Post launch, ssh from master to workers is used only if tunnel is true
while length(additional_workers) > 0
all_new_workers=[]
for (w_initial, new_workers) in additional_workers
num_new_w = length(new_workers)
tunnel = get(w_initial.config.tunnel, false)
maxp = get(w_initial.config.max_parallel, 0)
if tunnel && (maxp > 0)
num_in_p = min(maxp, num_new_w)
else
num_in_p = num_new_w # Do not rate-limit connect
end
for i in 1:num_in_p
(pid, bind_addr, port) = shift!(new_workers)
wconfig = WorkerConfig()
for x in [:host, :tunnel, :sshflags, :exeflags, :exename]
setfield!(wconfig, x, getfield(w_initial.config, x))
end
wconfig.bind_addr = bind_addr
wconfig.port = port
new_w = connect_n_create_worker(w_initial.manager, pid, wconfig)
push!(all_new_workers, new_w)
end
end
rr_list=[]
for new_w in all_new_workers
rr=setup_worker(PGRP, new_w)
push!(rr_list, rr)
push!(rr_launched, rr)
end
# It is important to wait for all of newly launched workers to finish
# connection setup, so that all the workers are aware of all other workers
[wait(rr) for rr in rr_list]
filter!(x->((w_initial, new_workers) = x; length(new_workers) > 0), additional_workers)
end
end
function connect_n_create_worker(manager, pid, wconfig)
# initiate a connect. Does not wait for connection completion in case of TCP.
(r_s, w_s) = connect(manager, pid, wconfig)
w = Worker(pid, r_s, w_s, manager, wconfig)
register_worker(w)
# install a finalizer to perform cleanup if necessary
finalizer(w, (w)->if myid() == 1 manage(w.manager, w.id, w.config, :finalize) end)
w
end
function setup_worker(pg::ProcessGroup, w)
# only node 1 can add new nodes, since nobody else has the full list of address:port
assert(LPROC.id == 1)
# set when the new worker has finshed connections with all other workers
rr_join = RemoteRef()
# Start a new task to handle inbound messages from connected worker in master.
# Also calls `wait_connected` on TCP streams.
process_messages(w.r_stream, w.w_stream; ntfy_join_complete=rr_join)
# send address information of all workers to the new worker.
# Cluster managers set the address of each worker in `WorkerConfig.connect_at`.
# A new worker uses this to setup a all-to-all network. Workers with higher pids connect to
# workers with lower pids. Except process 1 (master) which initiates connections
# to all workers.
# Flow:
# - master sends (:join_pgrp, list_of_all_worker_addresses) to all workers
# - On each worker
# - each worker sends a :identify_socket to all workers less than its pid
# - each worker then sends a :join_complete back to the master along with its OS_PID and NUM_CORES
# - once master receives a :join_complete it triggers rr_join (signifies that worker setup is complete)
all_locs = map(x -> isa(x, Worker) ? (get(x.config.connect_at, ()), x.id, isa(x.manager, LocalManager)) : ((), x.id, true), pg.workers)
send_msg_now(w, :join_pgrp, w.id, all_locs, isa(w.manager, LocalManager))
@schedule manage(w.manager, w.id, w.config, :register)
rr_join
end
# Called on the first worker on a remote host. Used to optimize launching
# of multiple workers on a remote host (to leverage multi-core)
function launch_additional(np::Integer, pids::Array, cmd::Cmd)
assert(np == length(pids))
io_objs = cell(np)
addresses = cell(np)
for i in 1:np
io, pobj = open(detach(cmd), "r")
io_objs[i] = io
end
for (i,io) in enumerate(io_objs)
(host, port) = read_worker_host_port(io)
addresses[i] = (pids[i], host, port)
let io=io, pid=pids[i]
redirect_worker_output("$pid", io)
end
end
addresses
end
## higher-level functions: spawn, pmap, pfor, etc. ##
let nextidx = 0
global chooseproc
function chooseproc(thunk::Function)
p = -1
env = thunk.env
if isa(env,Tuple)
for v in env
if isa(v,Box)
v = v.contents
end
if isa(v,RemoteRef)
p = v.where; break
end
end
end
if p == -1
p = workers()[(nextidx % nworkers()) + 1]
nextidx += 1
end
p
end
end
spawnat(p, thunk) = sync_add(remotecall(p, thunk))
spawn_somewhere(thunk) = spawnat(chooseproc(thunk),thunk)
macro spawn(expr)
expr = localize_vars(:(()->($expr)), false)
:(spawn_somewhere($(esc(expr))))
end
macro spawnat(p, expr)
expr = localize_vars(:(()->($expr)), false)
:(spawnat($(esc(p)), $(esc(expr))))
end
macro fetch(expr)
expr = localize_vars(:(()->($expr)), false)
quote
thunk = $(esc(expr))
remotecall_fetch(chooseproc(thunk), thunk)
end
end
macro fetchfrom(p, expr)
expr = localize_vars(:(()->($expr)), false)
:(remotecall_fetch($(esc(p)), $(esc(expr))))
end
function at_each(f, args...)
for w in PGRP.workers
sync_add(remotecall(w.id, f, args...))
end
end
macro everywhere(ex)
quote
@sync begin
at_each(()->eval(Main,$(Expr(:quote,ex))))
end
end
end
function pmap_static(f, lsts...)
np = nprocs()
n = length(lsts[1])
Any[ remotecall(PGRP.workers[(i-1)%np+1].id, f, map(L->L[i], lsts)...) for i = 1:n ]
end
pmap(f) = f()
# dynamic scheduling by creating a local task to feed work to each processor
# as it finishes.
# example unbalanced workload:
# rsym(n) = (a=rand(n,n);a*a')
# L = {rsym(200),rsym(1000),rsym(200),rsym(1000),rsym(200),rsym(1000),rsym(200),rsym(1000)};
# pmap(eig, L);
function pmap(f, lsts...; err_retry=true, err_stop=false, pids = workers())
len = length(lsts)
results = Dict{Int,Any}()
retryqueue = []
task_in_err = false
is_task_in_error() = task_in_err
set_task_in_error() = (task_in_err = true)
nextidx = 0
getnextidx() = (nextidx += 1)
states = [start(lsts[idx]) for idx in 1:len]
function getnext_tasklet()
if is_task_in_error() && err_stop
return nothing
elseif !any(idx->done(lsts[idx],states[idx]), 1:len)
nxts = [next(lsts[idx],states[idx]) for idx in 1:len]
for idx in 1:len; states[idx] = nxts[idx][2]; end
nxtvals = [x[1] for x in nxts]
return (getnextidx(), nxtvals)
elseif !isempty(retryqueue)
return shift!(retryqueue)
else
return nothing
end
end
@sync begin
for wpid in pids
@async begin
tasklet = getnext_tasklet()
while (tasklet != nothing)
(idx, fvals) = tasklet
try
result = remotecall_fetch(wpid, f, fvals...)
if isa(result, Exception)
((wpid == myid()) ? rethrow(result) : throw(result))
else
results[idx] = result
end
catch ex
if err_retry
push!(retryqueue, (idx,fvals, ex))
else
results[idx] = ex
end
set_task_in_error()
break # remove this worker from accepting any more tasks
end
tasklet = getnext_tasklet()
end
end
end
end
for failure in retryqueue
results[failure[1]] = failure[3]
end
[results[x] for x in 1:nextidx]
end
# Statically split range [1,N] into equal sized chunks for np processors
function splitrange(N::Int, np::Int)
each = div(N,np)
extras = rem(N,np)
nchunks = each > 0 ? np : extras
chunks = Array(UnitRange{Int}, nchunks)
lo = 1
for i in 1:nchunks
hi = lo + each - 1
if extras > 0
hi += 1
extras -= 1
end
chunks[i] = lo:hi
lo = hi+1
end
return chunks
end
function preduce(reducer, f, N::Int)
chunks = splitrange(N, nworkers())
results = cell(length(chunks))
for i in 1:length(chunks)
results[i] = @spawn f(first(chunks[i]), last(chunks[i]))
end
mapreduce(fetch, reducer, results)
end
function pfor(f, N::Int)
[@spawn f(first(c), last(c)) for c in splitrange(N, nworkers())]
end
function make_preduce_body(reducer, var, body, ran)
localize_vars(
quote
function (lo::Int, hi::Int)
R = $(esc(ran))
$(esc(var)) = R[lo]
ac = $(esc(body))
if lo != hi
for $(esc(var)) in R[(lo+1):hi]
ac = ($(esc(reducer)))(ac, $(esc(body)))
end
end
ac
end
end
)
end
function make_pfor_body(var, body, ran)
localize_vars(
quote
function (lo::Int, hi::Int)
for $(esc(var)) in ($(esc(ran)))[lo:hi]
$(esc(body))
end
end
end
)
end
macro parallel(args...)
na = length(args)
if na==1
loop = args[1]
if isa(loop,Expr) && loop.head === :comprehension
ex = loop.args[1]
loop.args[1] = esc(ex)
nd = length(loop.args)-1
ranges = map(e->esc(e.args[2]), loop.args[2:end])
for i=1:nd
var = loop.args[1+i].args[1]
loop.args[1+i] = :( $(esc(var)) = ($(ranges[i]))[I[$i]] )
end
return :( DArray((I::(UnitRange{Int}...))->($loop),
tuple($(map(r->:(length($r)),ranges)...))) )
end
elseif na==2
reducer = args[1]
loop = args[2]
else
throw(ArgumentError("wrong number of arguments to @parallel"))
end
if !isa(loop,Expr) || !is(loop.head,:for)
error("malformed @parallel loop")
end
var = loop.args[1].args[1]
r = loop.args[1].args[2]
body = loop.args[2]
if na==1
quote
pfor($(make_pfor_body(var, body, r)), length($(esc(r))))
end
else
quote
preduce($(esc(reducer)),
$(make_preduce_body(reducer, var, body, r)), length($(esc(r))))
end
end
end
function check_master_connect(timeout)
# If we do not have at least process 1 connect to us within timeout
# we log an error and exit, unless we're running on valgrind
if ccall(:jl_running_on_valgrind,Cint,()) != 0
return
end
@schedule begin
start = time()
while !haskey(map_pid_wrkr, 1) && (time() - start) < timeout
sleep(1.0)
end
if !haskey(map_pid_wrkr, 1)
print(STDERR, "Master process (id 1) could not connect within $timeout seconds.\nexiting.\n")
exit(1)
end
end
end
function timedwait(testcb::Function, secs::Float64; pollint::Float64=0.1)
start = time()
done = RemoteRef()
timercb(aw) = begin
try
if testcb()
put!(done, :ok)
elseif (time() - start) > secs
put!(done, :timed_out)
end
catch e
put!(done, :error)
finally
isready(done) && stop_timer(aw)
end
end
if !testcb()
t = Timer(timercb)
start_timer(t, pollint, pollint)
ret = fetch(done)
stop_timer(t)
else
ret = :ok
end
ret
end
function interrupt(pid::Integer)
assert(myid() == 1)
w = map_pid_wrkr[pid]
if isa(w, Worker)
manage(w.manager, w.id, w.config, :interrupt)
end
end
interrupt(pids::Integer...) = interrupt([pids...])
function interrupt(pids::AbstractVector=workers())
assert(myid() == 1)
@sync begin
for pid in pids
@async interrupt(pid)
end
end
end
function disable_nagle(sock)
# disable nagle on all OSes
ccall(:uv_tcp_nodelay, Cint, (Ptr{Void}, Cint), sock.handle, 1)
@linux_only begin
# tcp_quickack is a linux only option
if ccall(:jl_tcp_quickack, Cint, (Ptr{Void}, Cint), sock.handle, 1) < 0
warn_once("Parallel networking unoptimized ( Error enabling TCP_QUICKACK : ", strerror(errno()), " )")
end
end
end
function check_same_host(pids)
if myid() != 1
return remotecall_fetch(1, check_same_host, pids)
else
# We checkfirst if all test pids have been started using the local manager,
# else we check for the same bind_to addr. This handles the special case
# where the local ip address may change - as during a system sleep/awake
if all(p -> (p==1) || (isa(map_pid_wrkr[p].manager, LocalManager)), pids)
return true
else
first_bind_addr = get(map_pid_wrkr[pids[1]].config.bind_addr)
return all(p -> (p != 1) && (get(map_pid_wrkr[p].config.bind_addr) == first_bind_addr), pids[2:end])
end
end
end
function terminate_all_workers()
if myid() != 1
return
end
if nprocs() > 1
ret = rmprocs(workers(); waitfor=0.5)
if ret != :ok
warn("Forcibly interrupting busy workers")
# Might be computation bound, interrupt them and try again
interrupt(workers())
ret = rmprocs(workers(); waitfor=0.5)
if ret != :ok
warn("Unable to terminate all workers")
end
end
end
end
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