node,timers: fix beforeExit with unrefed timers

src/node.cc

@@ -3961,18 +3961,26 @@ static void StartNodeInstance(void* arg) {
     {
       SealHandleScope seal(isolate);
       bool more;
+      uv_loop_t* event_loop = env->event_loop();
+
       do {
         v8::platform::PumpMessageLoop(default_platform, isolate);
-        more = uv_run(env->event_loop(), UV_RUN_ONCE);
+        more = uv_run(event_loop, UV_RUN_ONCE);
 
         if (more == false) {
           v8::platform::PumpMessageLoop(default_platform, isolate);
           EmitBeforeExit(env);
 
+          // If there are only unrefed handles left, we need to run an
+          // extra event loop turn to purge the unrefed handles.
+          if (event_loop->active_handles == 0 &&
+              event_loop->handle_queue[0] != event_loop->handle_queue[1])
+            uv_run(event_loop, UV_RUN_NOWAIT);
+
           // Emit `beforeExit` if the loop became alive either after emitting
           // event, or after running some callbacks.
-          more = uv_loop_alive(env->event_loop());
-          if (uv_run(env->event_loop(), UV_RUN_NOWAIT) != 0)
+          more = uv_loop_alive(event_loop);
+          if (uv_run(event_loop, UV_RUN_NOWAIT) != 0)
             more = true;
         }
       } while (more == true);

test/parallel/test-beforeexit-event.js

@@ -1,6 +1,6 @@
 'use strict';
 var assert = require('assert');
-var net = require('net');
+var fs = require('fs');
 var util = require('util');
 var common = require('../common');
 var revivals = 0;
@@ -23,18 +23,18 @@ function tryTimer() {
   setTimeout(function() {
     console.log('timeout cb, do another once beforeExit');
     revivals++;
-    process.once('beforeExit', tryListen);
+    process.once('beforeExit', tryFile);
   }, 1);
 }
 
-function tryListen() {
-  console.log('create a server');
-  net.createServer()
-    .listen(common.PORT)
-    .on('listening', function() {
-      revivals++;
-      this.close();
-    });
+function tryFile() {
+  console.log('open a file');
+  fs.open(__filename, 'r', (err, fd) => {
+    if (err) throw err;
+
+    revivals++;
+    fs.closeSync(fd);
+  });
 }
 
 process.on('exit', function() {

test/parallel/test-timers-unrefed-in-beforeexit.js

@@ -0,0 +1,20 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+
+var once = 0;
+
+process.on('beforeExit', () => {
+  if (once > 1)
+    throw new RangeError('beforeExit should only have been called once!');
+
+  setTimeout(() => {}, 1).unref();
+  once++;
+});
+
+process.on('exit', (code) => {
+  if (code !== 0) return;
+
+  assert.strictEqual(once, 1);
+});