doc: specify cluster worker.kill() caveat

doc/api/cluster.md

@@ -394,6 +394,11 @@ This function will kill the worker. In the master, it does this by disconnecting
 the `worker.process`, and once disconnected, killing with `signal`. In the
 worker, it does it by disconnecting the channel, and then exiting with code `0`.
 
+Because `kill()` attempts to gracefully disconnect the worker process, it is
+susceptible to waiting indefinitely for the disconnect to complete. For example,
+if the worker enters an infinite loop, a graceful disconnect will never occur.
+If the graceful disconnect behavior is not needed, use `worker.process.kill()`.
+
 Causes `.exitedAfterDisconnect` to be set.
 
 This method is aliased as `worker.destroy()` for backwards compatibility.

test/parallel/test-cluster-kill-infinite-loop.js

@@ -0,0 +1,21 @@
+'use strict';
+const common = require('../common');
+const cluster = require('cluster');
+const assert = require('assert');
+
+if (cluster.isMaster) {
+  const worker = cluster.fork();
+
+  worker.on('online', common.mustCall(() => {
+    // Use worker.process.kill() instead of worker.kill() because the latter
+    // waits for a graceful disconnect, which will never happen.
+    worker.process.kill();
+  }));
+
+  worker.on('exit', common.mustCall((code, signal) => {
+    assert.strictEqual(code, null);
+    assert.strictEqual(signal, 'SIGTERM');
+  }));
+} else {
+  while (true) {}
+}