fix: Child.unref() unrefs stdio streams properly (denoland#15275)

cli/tests/unit/spawn_test.ts

@@ -723,8 +723,29 @@ Deno.test(
  const program = `
 const child = await Deno.spawnChild(Deno.execPath(), {
  cwd: Deno.args[0],
+ stdout: "piped",
  args: ["run", "-A", "--unstable", Deno.args[1]],
 });
+const readable = child.stdout.pipeThrough(new TextDecoderStream());
+const reader = readable.getReader();
+// set up an interval that will end after reading a few messages from stdout, 
+// to verify that stdio streams are properly unrefed
+let count = 0;
+let interval;
+interval = setInterval(async () => {
+ count += 1;
+ if (count > 10) {
+ clearInterval(interval);
+ console.log("cleared interval");
+ }
+ const res = await reader.read();
+ if (res.done) {
+ throw new Error("stream shouldn't be done");
+ }
+ if (res.value.trim() != "hello from interval") {
+ throw new Error("invalid message received");
+ }
+}, 120);
 console.log("spawned pid", child.pid);
 child.unref();
 `;
@@ -740,15 +761,19 @@ setInterval(() => {
  // In this subprocess we are spawning another subprocess which has
  // an infite interval set. Following call would never resolve unless
  // child process gets unrefed.
- const { success, stdout } = await Deno.spawn(Deno.execPath(), {
+ const { success, stdout, stderr } = await Deno.spawn(Deno.execPath(), {
  cwd,
  args: ["run", "-A", "--unstable", programFile, cwd, childProgramFile],
  });
 
  assert(success);
  const stdoutText = new TextDecoder().decode(stdout);
- const pidStr = stdoutText.split(" ").at(-1);
+ const stderrText = new TextDecoder().decode(stderr);
+ assert(stderrText.length == 0);
+ const [line1, line2] = stdoutText.split("\n");
+ const pidStr = line1.split(" ").at(-1);
  assert(pidStr);
+ assertEquals(line2, "cleared interval");
  const pid = Number.parseInt(pidStr, 10);
  await Deno.remove(cwd, { recursive: true });
  // Child process should have been killed when parent process exits.

runtime/js/40_spawn.js

@@ -75,6 +75,7 @@
  class Child {
  #rid;
  #waitPromiseId;
+ #unrefed = false;
 
  #pid;
  get pid() {
@@ -132,13 +133,15 @@
  this.#stdoutRid = stdoutRid;
  this.#stdout = readableStreamForRid(stdoutRid, (promise) => {
  this.#stdoutPromiseId = promise[promiseIdSymbol];
+ if (this.#unrefed) core.unrefOp(this.#stdoutPromiseId);
  });
  }
 
  if (stderrRid !== null) {
  this.#stderrRid = stderrRid;
  this.#stderr = readableStreamForRid(stderrRid, (promise) => {
  this.#stderrPromiseId = promise[promiseIdSymbol];
+ if (this.#unrefed) core.unrefOp(this.#stderrPromiseId);
  });
  }
 
@@ -204,12 +207,14 @@
  }
 
  ref() {
+ this.#unrefed = false;
  core.refOp(this.#waitPromiseId);
  if (this.#stdoutPromiseId) core.refOp(this.#stdoutPromiseId);
  if (this.#stderrPromiseId) core.refOp(this.#stderrPromiseId);
  }
 
  unref() {
+ this.#unrefed = true;
  core.unrefOp(this.#waitPromiseId);
  if (this.#stdoutPromiseId) core.unrefOp(this.#stdoutPromiseId);
  if (this.#stderrPromiseId) core.unrefOp(this.#stderrPromiseId);