fix(workers): Make `worker.terminate()` not immediately kill the isolate (#12831)

Due to a bug in V8, terminating an isolate while a module with top-level
await is being evaluated would crash the process. This change makes it
so calling `worker.terminate()` will signal the worker to terminate at
the next iteration of the event loop, and it schedules a proper
termination of the worker's isolate after 2 seconds.

1 files changed, 21 insertions, 0 deletions

diff --git a/cli/tests/testdata/workers/terminate_tla_crash.js b/cli/tests/testdata/workers/terminate_tla_crash.js
new file mode 100644
index 000000000..f793b8c8e
--- /dev/null
+++ b/cli/tests/testdata/workers/terminate_tla_crash.js
@@ -0,0 +1,21 @@
+// Test for https://github.com/denoland/deno/issues/12658
+//
+// If a worker is terminated immediately after construction, and the worker's
+// main module uses top-level await, V8 has a chance to crash.
+//
+// These crashes are so rare in debug mode that I've only seen them once. They
+// happen a lot more often in release mode.
+
+const workerModule = `
+  await new Promise(resolve => setTimeout(resolve, 1000));
+`;
+
+// Iterating 10 times to increase the likelihood of triggering the crash, at
+// least in release mode.
+for (let i = 0; i < 10; i++) {
+  const worker = new Worker(
+    `data:application/javascript;base64,${btoa(workerModule)}`,
+    { type: "module" },
+  );
+  worker.terminate();
+}