fixup! Make worker state variable threadsafe

Author: JamesWrigley

test/threads.jl

@@ -29,7 +29,7 @@ isfailed(rr) = fetch_from_owner(istaskfailed, rr)
     ws = ts = product(1:2, 1:2)
     @testset "from worker $w1 to $w2 via 1" for (w1, w2) in ws
         @testset "from thread $w1.$t1 to $w2.$t2" for (t1, t2) in ts
-          # We want (the default) lazyness, so that we wait for `Worker.c_state`!
+            # We want (the default) laziness, so that we wait for `Worker.c_state`!
             procs_added = addprocs(2; exeflags, lazy=true)
             @everywhere procs_added using Base.Threads
 
@@ -44,11 +44,12 @@ isfailed(rr) = fetch_from_owner(istaskfailed, rr)
                 take!(chan)
             end
 
-            # Wait on the spawned tasks on the owner
-            @sync begin
-                Threads.@spawn fetch_from_owner(wait, recv)
-                Threads.@spawn fetch_from_owner(wait, send)
-            end
+            # Wait on the spawned tasks on the owner. Note that we use
+            # timedwait() instead of @sync to avoid deadlocks.
+            t1 = Threads.@spawn fetch_from_owner(wait, recv)
+            t2 = Threads.@spawn fetch_from_owner(wait, send)
+            @test timedwait(() -> istaskdone(t1), 5) == :ok
+            @test timedwait(() -> istaskdone(t2), 5) == :ok
 
             # Check the tasks
             @test isdone(send)