Use hostname on macOS to lookup local host name

This is to work around a five second lag when using the JDK approach, see https://bugs.openjdk.java.net/browse/JDK-8143378.

subprojects/messaging/src/main/java/org/gradle/internal/remote/internal/inet/InetAddressFactory.java

@@ -15,10 +15,13 @@
  */
 package org.gradle.internal.remote.internal.inet;
 
+import org.gradle.internal.os.OperatingSystem;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import javax.annotation.Nullable;
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.UnknownHostException;
@@ -38,16 +41,41 @@ public class InetAddressFactory {
     private String hostName;
 
     public String getHostname() {
-        synchronized (lock) {
-            if (hostName == null) {
-                try {
-                    hostName = InetAddress.getLocalHost().getHostName();
-                } catch (UnknownHostException e) {
-                    hostName = getCommunicationAddresses().get(0).toString();
+        if (hostName == null) {
+            synchronized (lock) {
+                // Work around https://bugs.openjdk.java.net/browse/JDK-8143378 on macOS
+                // See also https://stackoverflow.com/a/39698914
+                if (hostName == null && OperatingSystem.current() == OperatingSystem.MAC_OS) {
+                    ProcessBuilder builder = new ProcessBuilder("hostname");
+                    try {
+                        Process process = builder.start();
+                        int result = process.waitFor();
+                        if (result == 0) {
+                            BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
+                            try {
+                                String line = reader.readLine();
+                                if (line != null) {
+                                    hostName = line;
+                                }
+                            } finally {
+                                reader.close();
+                            }
+                        }
+                    } catch (Exception e) {
+                        logger.debug("Couldn't resolve hostname by running hostname, falling back to using JDK", e);
+                    }
+                }
+
+                if (hostName == null) {
+                    try {
+                        hostName = InetAddress.getLocalHost().getHostName();
+                    } catch (UnknownHostException e) {
+                        hostName = getCommunicationAddresses().get(0).toString();
+                    }
                 }
             }
-            return hostName;
         }
+        return hostName;
     }
 
     /**