Use Threads.@spawn instead of @async

src/DistributedStdlibWorker.jl

@@ -27,7 +27,7 @@ mutable struct DistributedStdlibWorker <: AbstractWorker
         # TODO: process preamble from Pluto?
 
         # There's no reason to keep the worker process alive after the manager loses its handle.
-        w = finalizer(w -> @async(stop(w)),
+        w = finalizer(w -> Threads.@spawn(stop(w)),
             new(pid, true)
         )
         atexit(() -> stop(w))
@@ -52,7 +52,7 @@ macro transform_exception(worker, ex)
 end
 
 function remote_call(f, w::DistributedStdlibWorker, args...; kwargs...)
-    @async Distributed.remotecall_fetch(f, w.pid, args...; kwargs...)
+    Threads.@spawn Distributed.remotecall_fetch(f, w.pid, args...; kwargs...)
 end
 
 function remote_call_fetch(f, w::DistributedStdlibWorker, args...; kwargs...)

src/Malt.jl

@@ -123,7 +123,7 @@ mutable struct Worker <: AbstractWorker
 
 
         # There's no reason to keep the worker process alive after the manager loses its handle.
-        w = finalizer(w -> @async(stop(w)),
+        w = finalizer(w -> Threads.@spawn(stop(w)),
             new(
                 port, 
                 proc, 
@@ -147,7 +147,7 @@ Base.summary(io::IO, w::Worker) = write(io, "Malt.Worker on port $(w.port) with
 
 
 function _exit_loop(worker::Worker)
-    @async for _i in Iterators.countfrom(1)
+    Threads.@spawn for _i in Iterators.countfrom(1)
         try
             if !isrunning(worker)
                 # the worker got shut down, which means that we will never receive one of the expected_replies. So let's give all of them a special_worker_terminated reply.
@@ -172,7 +172,7 @@ function _receive_loop(worker::Worker)
     # instead of
     # `while true`
     # as a workaround for https://github.com/JuliaLang/julia/issues/37154
-    @async for _i in Iterators.countfrom(1)
+    Threads.@spawn for _i in Iterators.countfrom(1)
         try
             if !isopen(io)
                 @debug("HOST: io closed.")
@@ -283,7 +283,7 @@ _new_do_msg(f::Function, args, kwargs) = (
 #     # TODO: `while` instead of `if`?
 #     if w.current_socket === nothing || !isopen(w.current_socket)
 #         w.current_socket = connect(w.port)
-#         @async _receive_loop(w)
+#         Threads.@spawn _receive_loop(w)
 #     end
 #     return w
 # end
@@ -337,12 +337,12 @@ function _send_receive(w::Worker, msg_type::UInt8, msg_data)
 end
 
 """
-`@async(_wait_for_response) ∘ _send_msg`
+`Threads.@spawn(_wait_for_response) ∘ _send_msg`
 """
 function _send_receive_async(w::Worker, msg_type::UInt8, msg_data, output_transformation=identity)::Task
     # TODO: Unwrap TaskFailedExceptions
     msg_id = _send_msg(w, msg_type, msg_data, true)
-    return @async output_transformation(_wait_for_response(w, msg_id))
+    return Threads.@spawn output_transformation(_wait_for_response(w, msg_id))
 end
 
 
@@ -375,7 +375,7 @@ function remote_call(f, w::Worker, args...; kwargs...)
     )
 end
 function remote_call(f, w::InProcessWorker, args...; kwargs...)
-    w.latest_request_task = @async remote_call_fetch(f, w, args...; kwargs...)
+    w.latest_request_task = Threads.@spawn remote_call_fetch(f, w, args...; kwargs...)
 end
 function remote_call_fetch(f, w::InProcessWorker, args...; kwargs...)
     try
@@ -446,7 +446,7 @@ function remote_do(f, w::Worker, args...; kwargs...)
     nothing
 end
 function remote_do(f, ::InProcessWorker, args...; kwargs...)
-    @async f(args...; kwargs...)
+    Threads.@spawn f(args...; kwargs...)
     nothing
 end
 
@@ -645,7 +645,7 @@ function _rethrow_to_repl(e::InterruptException; rethrow_regular::Bool=false)
        Base.active_repl_backend.in_eval
 
         @debug "HOST: Rethrowing interrupt to REPL"
-        @async Base.schedule(Base.active_repl_backend.backend_task, e; error=true)
+        Threads.@spawn Base.schedule(Base.active_repl_backend.backend_task, e; error=true)
     elseif rethrow_regular
         @debug "HOST: Don't know what to do with this interrupt, rethrowing" exception = (e, catch_backtrace())
         rethrow(e)

src/worker.jl

@@ -115,7 +115,7 @@ interrupt(::Nothing) = nothing
 function handle(::Val{MsgType.from_host_call_with_response}, socket, msg, msg_id::MsgID)
     f, args, kwargs, respond_with_nothing = msg
 
-    @async begin
+    Threads.@spawn begin
         result, success = try
             result = f(args...; kwargs...)
 
@@ -139,7 +139,7 @@ end
 function handle(::Val{MsgType.from_host_call_without_response}, socket, msg, msg_id::MsgID)
     f, args, kwargs, _ignored = msg
 
-    @async try
+    Threads.@spawn try
         f(args...; kwargs...)
     catch e
         @warn("WORKER: Got exception while running call without response", exception=(e, catch_backtrace()))

test/basic.jl

@@ -128,7 +128,7 @@
 
 
 
-        t = @async begin
+        t = Threads.@spawn begin
             for i in 1:2*channel_size
                 @test take!(lc) == i
             end