fix(node): child_process kill cancel pending IPC reads (#21647)

cli/tests/unit_node/child_process_test.ts

@@ -731,3 +731,26 @@ Deno.test(function spawnSyncExitNonZero() {
 
   assertEquals(ret.status, 22);
 });
+
+// https://github.com/denoland/deno/issues/21630
+Deno.test(async function forkIpcKillDoesNotHang() {
+  const testdataDir = path.join(
+    path.dirname(path.fromFileUrl(import.meta.url)),
+    "testdata",
+  );
+  const script = path.join(
+    testdataDir,
+    "node_modules",
+    "foo",
+    "index.js",
+  );
+  const p = Promise.withResolvers<void>();
+  const cp = CP.fork(script, [], {
+    cwd: testdataDir,
+    stdio: ["inherit", "inherit", "inherit", "ipc"],
+  });
+  cp.on("close", () => p.resolve());
+  cp.kill();
+
+  await p.promise;
+});

ext/node/polyfills/internal/child_process.ts

@@ -296,6 +296,10 @@ export class ChildProcess extends EventEmitter {
         throw err;
       }
     }
+
+    /* Cancel any pending IPC I/O */
+    this.disconnect?.();
+
     this.killed = true;
     this.signalCode = denoSignal;
     return this.killed;