fix: ignore TIMERWRAP in AsyncHooksContextManager (#1530)

Co-authored-by: Daniel Dyla <dyladan@users.noreply.github.com>

packages/opentelemetry-context-async-hooks/src/AsyncHooksContextManager.ts

@@ -66,8 +66,15 @@ export class AsyncHooksContextManager extends AbstractAsyncHooksContextManager {
    * Init hook will be called when userland create a async context, setting the
    * context as the current one if it exist.
    * @param uid id of the async context
+   * @param type the resource type
    */
-  private _init(uid: number) {
+  private _init(uid: number, type: string) {
+    // ignore TIMERWRAP as they combine timers with same timeout which can lead to
+    // false context propagation. TIMERWRAP has been removed in node 11
+    // every timer has it's own `Timeout` resource anyway which is used to propagete
+    // context.
+    if (type === 'TIMERWRAP') return;
+
     const context = this._stack[this._stack.length - 1];
     if (context !== undefined) {
       this._contexts.set(uid, context);

packages/opentelemetry-context-async-hooks/test/AsyncHooksContextManager.test.ts

@@ -222,6 +222,34 @@ for (const contextManagerClass of [
         });
         assert.strictEqual(contextManager.active(), Context.ROOT_CONTEXT);
       });
+
+      it('should work with timers using the same timeout', done => {
+        let cnt = 3;
+        function countDown() {
+          cnt--;
+          if (cnt === 0) done();
+          if (cnt < 0) throw new Error('too many calls to countDown()');
+        }
+
+        const time1 = 2;
+        const time2 = time1 + 1;
+        const rootCtx = contextManager.active();
+        const innerCtx = rootCtx.setValue(Symbol('test'), 23);
+        contextManager.with(innerCtx, () => {
+          setTimeout(() => {
+            assert.strictEqual(contextManager.active(), innerCtx);
+            countDown();
+          }, time1);
+        });
+        setTimeout(() => {
+          assert.strictEqual(contextManager.active(), rootCtx);
+          countDown();
+        }, time1);
+        setTimeout(() => {
+          assert.strictEqual(contextManager.active(), rootCtx);
+          countDown();
+        }, time2);
+      });
     });
 
     describe('.bind(function)', () => {