Fix hangs when deleting / recreating project root with the same name

lib/spring/application_manager.rb

@@ -32,7 +32,11 @@ def restart
     end
 
     def alive?
-      @pid
+      return false if @pid.nil?
+      Process.getpgid(@pid)
+      true
+    rescue Errno::ESRCH
+      false
     end
 
     def with_child
@@ -109,10 +113,24 @@ def start_child(preload = false)
         )
       end
 
-      start_wait_thread(pid, child) if child.gets
+      wait_for_child_to_boot
+      start_wait_thread(pid, child)
+    rescue => e
+      log "error while starting child: #{e.message}"
+      abort("error while starting child: #{e.message}")
+    ensure
       child_socket.close
     end
 
+    def wait_for_child_to_boot
+      timeout = 1
+      loop do
+        break if IO.select([child], nil, nil, timeout)
+        raise "child has exited unexpectedly" unless alive?
+      end
+      child.gets
+    end
+
     def start_wait_thread(pid, child)
       Process.detach(pid)
 

lib/spring/test/acceptance_test.rb

@@ -194,6 +194,23 @@ def self.omg
         assert_success app.spring_test_command
       end
 
+      test "deleting the app root should kill the server" do
+        app.run app.spring_test_command
+        assert spring_env.server_running?, "The server should be running but it isn't"
+        FileUtils.rm_rf(app.root)
+        sleep 2 # wait for the watcher to notice and react
+        assert !spring_env.server_running?, "The server should not be running but it is"
+      end
+
+      test "server restarts when the app root is deleted and recreated" do
+        assert_success app.spring_test_command
+        FileUtils.rm_rf(app.root)
+        sleep 1 # wait for the watcher to notice and react
+
+        generator.copy_to(app.root)
+        assert_success app.spring_test_command
+      end
+
       test "stop command kills server" do
         app.run app.spring_test_command
         assert spring_env.server_running?, "The server should be running but it isn't"