refactor(core): Allow multiple overflown responses in single poll (#9433)

This commit rewrites "JsRuntime::poll" function to fix a corner case that
might caused "overflown_response" to be overwritten by other overflown response.

The logic has been changed to allow returning multiple overflown response
alongside responses from shared queue.

2 files changed, 49 insertions, 0 deletions

diff --git a/cli/tests/workers/large_message_worker.js b/cli/tests/workers/large_message_worker.js
new file mode 100644
index 000000000..f7b7da8a0
--- /dev/null
+++ b/cli/tests/workers/large_message_worker.js
@@ -0,0 +1,14 @@
+// Copyright 2020 the Deno authors. All rights reserved. MIT license.
+
+const dataSmall = "";
+const dataLarge = "x".repeat(10 * 1024);
+
+onmessage = function (e) {
+  for (let i = 0; i <= 10; i++) {
+    if (i % 2 == 0) {
+      postMessage(dataLarge);
+    } else {
+      postMessage(dataSmall);
+    }
+  }
+};
diff --git a/cli/tests/workers_large_message_bench.ts b/cli/tests/workers_large_message_bench.ts
new file mode 100644
index 000000000..9cda5a40d
--- /dev/null
+++ b/cli/tests/workers_large_message_bench.ts
@@ -0,0 +1,35 @@
+// Copyright 2020 the Deno authors. All rights reserved. MIT license.
+
+// deno-lint-ignore-file
+
+import { deferred } from "../../test_util/std/async/deferred.ts";
+
+function oneWorker(i: any): Promise<void> {
+  return new Promise<void>((resolve) => {
+    let countDown = 10;
+    const worker = new Worker(
+      new URL("workers/large_message_worker.js", import.meta.url).href,
+      { type: "module" },
+    );
+    worker.onmessage = (e): void => {
+      if (countDown > 0) {
+        countDown--;
+        return;
+      }
+      worker.terminate();
+      resolve();
+    };
+    worker.postMessage("hi " + i);
+  });
+}
+
+function bench(): Promise<any> {
+  let promises = [];
+  for (let i = 0; i < 50; i++) {
+    promises.push(oneWorker(i));
+  }
+
+  return Promise.all(promises);
+}
+
+bench();