worker,src: display remaining handles if `uv_loop_close` fails

Right now, we crash the process if there are handles remaining
on the event loop when we exit (except for the main thread).

This does not provide a lot of information about causes, though;
in particular, we don’t show which handles are pending and
who own them.

This patch adds debug output to these cases to help with the
situation.

PR-URL: https://github.com/nodejs/node/pull/21238
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

3 files changed, 80 insertions, 0 deletions

diff --git a/test/addons/uv-handle-leak/binding.cc b/test/addons/uv-handle-leak/binding.cc
new file mode 100644
index 0000000000..c2e5f0bf27
--- /dev/null
+++ b/test/addons/uv-handle-leak/binding.cc
@@ -0,0 +1,48 @@
+#include <node.h>
+#include <v8.h>
+#include <uv.h>
+
+using v8::Context;
+using v8::FunctionCallbackInfo;
+using v8::Isolate;
+using v8::Local;
+using v8::Object;
+using v8::Value;
+
+// Give these things names in the public namespace so that we can see
+// them show up in symbol dumps.
+void CloseCallback(uv_handle_t* handle) {}
+
+class ExampleOwnerClass {
+ public:
+  virtual ~ExampleOwnerClass() {}
+};
+
+ExampleOwnerClass example_instance;
+
+void LeakHandle(const FunctionCallbackInfo<Value>& args) {
+  Isolate* isolate = args.GetIsolate();
+  Local<Context> context = isolate->GetCurrentContext();
+  uv_loop_t* loop = node::GetCurrentEventLoop(isolate);
+  assert(loop != nullptr);
+
+  uv_timer_t* leaked_timer = new uv_timer_t;
+  leaked_timer->close_cb = CloseCallback;
+
+  if (args[0]->IsNumber()) {
+    leaked_timer->data =
+        reinterpret_cast<void*>(args[0]->IntegerValue(context).FromJust());
+  } else {
+    leaked_timer->data = &example_instance;
+  }
+
+  uv_timer_init(loop, leaked_timer);
+  uv_timer_start(leaked_timer, [](uv_timer_t*){}, 1000, 1000);
+  uv_unref(reinterpret_cast<uv_handle_t*>(leaked_timer));
+}
+
+void Initialize(v8::Local<v8::Object> exports) {
+  NODE_SET_METHOD(exports, "leakHandle", LeakHandle);
+}
+
+NODE_MODULE(NODE_GYP_MODULE_NAME, Initialize)
diff --git a/test/addons/uv-handle-leak/binding.gyp b/test/addons/uv-handle-leak/binding.gyp
new file mode 100644
index 0000000000..7ede63d94a
--- /dev/null
+++ b/test/addons/uv-handle-leak/binding.gyp
@@ -0,0 +1,9 @@
+{
+  'targets': [
+    {
+      'target_name': 'binding',
+      'defines': [ 'V8_DEPRECATION_WARNINGS=1' ],
+      'sources': [ 'binding.cc' ]
+    }
+  ]
+}
diff --git a/test/addons/uv-handle-leak/test.js b/test/addons/uv-handle-leak/test.js
new file mode 100644
index 0000000000..73d40ca799
--- /dev/null
+++ b/test/addons/uv-handle-leak/test.js
@@ -0,0 +1,23 @@
+'use strict';
+const common = require('../../common');
+const bindingPath = require.resolve(`./build/${common.buildType}/binding`);
+const binding = require(bindingPath);
+
+// This tests checks that addons may leak libuv handles until process exit.
+// It’s really not a good idea to do so, but it tests existing behaviour
+// that likely can never be removed for backwards compatibility.
+
+// This has a sibling test in test/abort/ which checks output for failures
+// from workers.
+
+try {
+  // We don’t want to run this in Workers because they do actually enforce
+  // a clean-exit policy.
+  const { isMainThread } = require('worker_threads');
+  if (!isMainThread)
+    common.skip('Cannot run test in environment with clean-exit policy');
+} catch {}
+
+binding.leakHandle();
+binding.leakHandle(0);
+binding.leakHandle(1);