BREAKING: make Worker.deno unstable (#5128)

This commit makes "Worker.deno" option unstable.

Added new manual entry "docs/runtime/workers.md".

Removed stale workers tests.

1 files changed, 54 insertions, 0 deletions

diff --git a/docs/runtime/workers.md b/docs/runtime/workers.md
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+## Workers
+
+Deno supports
+[`Web Worker API`](https://developer.mozilla.org/en-US/docs/Web/API/Worker/Worker).
+
+Workers can be used to run code on multiple threads. Each instance of `Worker`
+is run on a separate thread, dedicated only to that worker.
+
+Currently Deno supports only `module` type workers; thus it's essential to pass
+`type: "module"` option when creating new worker:
+
+```ts
+// Good
+new Worker("./worker.js", { type: "module" });
+
+// Bad
+new Worker("./worker.js");
+new Worker("./worker.js", { type: "classic" });
+```
+
+### Using Deno in worker
+
+**UNSTABLE**: This feature is unstable and requires `--unstable` flag
+
+By default `Deno` namespace is not available in worker scope.
+
+To add `Deno` namespace pass `deno: true` option when creating new worker:
+
+```ts
+// main.js
+const worker = new Worker("./worker.js", { type: "module", deno: true });
+worker.postMessage({ filename: "./log.txt" });
+
+// worker.js
+self.onmessage = async (e) => {
+  const { filename } = e.data;
+  const text = await Deno.readTextFile(filename);
+  console.log(text);
+  self.close();
+};
+
+// log.txt
+hello world
+```
+
+```shell
+$ deno run --allow-read --unstable main.js
+hello world
+```
+
+When `Deno` namespace is available in worker scope; the worker inherits parent
+process permissions (the ones specified using `--allow-*` flags).
+
+We intend to make permissions configurable for workers.