Fix reuse of client port on Linux. Implement for OSX. [ci skip]

base/distributed/managers.jl

@@ -455,31 +455,45 @@ end
 const client_port = Ref{Cushort}(0)
 
 function socket_reuse_port()
-    s = TCPSocket()
+    s = TCPSocket(delay = false)
     client_host = Ref{Cuint}(0)
-    ccall(:jl_tcp_bind, Int32,
-            (Ptr{Void}, UInt16, UInt32, Cuint),
-            s.handle, hton(client_port.x), hton(UInt32(0)), 0) < 0 && throw(SystemError("bind() : "))
-
-    # TODO: Support OSX and change the above code to call setsockopt before bind once libuv provides
-    # early access to a socket fd, i.e., before a bind call.
 
-    @static if is_linux()
+    @static if is_linux() || is_apple()
         try
             rc = ccall(:jl_tcp_reuseport, Int32, (Ptr{Void},), s.handle)
             if rc > 0  # SO_REUSEPORT is unsupported, just return the ephemerally bound socket
                 return s
             elseif rc < 0
                 throw(SystemError("setsockopt() SO_REUSEPORT : "))
             end
-            getsockname(s)
         catch e
             # This is an issue only on systems with lots of client connections, hence delay the warning
             nworkers() > 128 && warn_once("Error trying to reuse client port number, falling back to plain socket : ", e)
             # provide a clean new socket
             return TCPSocket()
         end
     end
+
+    ccall(:jl_tcp_bind, Int32,
+            (Ptr{Void}, UInt16, UInt32, Cuint),
+            s.handle, hton(client_port[]), hton(UInt32(0)), 0) < 0 && throw(SystemError("bind() : "))
+
+    rport = Ref{Cushort}(0)
+    raddress = zeros(UInt8, 16)
+    rfamily = Ref{Cuint}(0)
+
+    r = ccall(:jl_tcp_getsockname, Int32,
+                (Ptr{Void}, Ref{Cushort}, Ptr{Void}, Ref{Cuint}),
+                s.handle, rport, raddress, rfamily)
+    Base.uv_error("cannot obtain socket name", r)
+    if r == 0
+        port = ntoh(rport[])
+    else
+        error("cannot obtain socket name")
+    end
+
+    client_port[] = port
+
     return s
 end
 

base/socket.jl

@@ -282,10 +282,17 @@ mutable struct TCPSocket <: LibuvStream
         return tcp
     end
 end
-function TCPSocket()
+function TCPSocket(; delay=true)  # kw arg "delay": if true, libuv delays creation of the socket
+                                  # fd till the first bind call
+
     tcp = TCPSocket(Libc.malloc(_sizeof_uv_tcp), StatusUninit)
-    err = ccall(:uv_tcp_init, Cint, (Ptr{Void}, Ptr{Void}),
-                eventloop(), tcp.handle)
+    if delay
+        err = ccall(:uv_tcp_init, Cint, (Ptr{Void}, Ptr{Void}),
+                    eventloop(), tcp.handle)
+    else
+        err = ccall(:uv_tcp_init_ex, Cint, (Ptr{Void}, Ptr{Void}, Cuint),
+                    eventloop(), tcp.handle, 2) # AF_INET is 2
+    end
     uv_error("failed to create tcp socket", err)
     tcp.status = StatusInit
     return tcp

test/distributed_exec.jl

@@ -12,6 +12,44 @@ include("testenv.jl")
 
 addprocs_with_testenv(4)
 
+# Test that the client port is reused. SO_REUSEPORT may not be supported on
+# all UNIX platforms, Linux kernels prior to 3.9 and older versions of OSX
+if is_unix()
+    # Run the test on all workers.
+    results = asyncmap(procs()) do p
+        remotecall_fetch(p) do
+            client_ports = []
+            for w in Base.Distributed.PGRP.workers
+                if isa(w, Base.Distributed.Worker)
+                    s = w.r_stream
+                    rport = Ref{Cushort}(0)
+                    raddress = zeros(UInt8, 16)
+                    rfamily = Ref{Cuint}(0)
+
+                    r = ccall(:jl_tcp_getsockname, Int32,
+                                (Ptr{Void}, Ref{Cushort}, Ptr{Void}, Ref{Cuint}),
+                                s.handle, rport, raddress, rfamily)
+                    Base.uv_error("cannot obtain socket name", r)
+                    if r == 0
+                        push!(client_ports, ntoh(rport[]))
+                    else
+                        error("cannot obtain socket name")
+                    end
+                end
+            end
+            @assert length(client_ports) == nworkers()
+            if !all(i -> i == client_ports[1], client_ports[2:end])
+                warn("SO_REUSEPORT TESTS FAILED. UNSUPPORTED/OLDER UNIX VERSION?")
+                return 0
+            end
+            return myid()
+        end
+    end
+
+    # Ensure that the code has indeed been executed on all processes
+    @test all(p -> p in results, procs())
+end
+
 id_me = myid()
 id_other = filter(x -> x != id_me, procs())[rand(1:(nprocs()-1))]