workers: fix spawning from preload scripts

Fix spawning nested worker threads from preload scripts and
warn about doing so.

Signed-off-by: James M Snell <jasnell@gmail.com>
Fixes: https://github.com/nodejs/node/issues/36531

PR-URL: https://github.com/nodejs/node/pull/37481
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

2 files changed, 19 insertions, 0 deletions

diff --git a/test/fixtures/worker-preload.js b/test/fixtures/worker-preload.js
new file mode 100644
index 00000000000..6e5c4a31d2f
--- /dev/null
+++ b/test/fixtures/worker-preload.js
@@ -0,0 +1,9 @@
+const {
+  Worker,
+  workerData,
+  threadId
+} = require('worker_threads');
+
+if (threadId < 2) {
+  new Worker('1 + 1', { eval: true });
+}
diff --git a/test/parallel/test-preload-worker.js b/test/parallel/test-preload-worker.js
new file mode 100644
index 00000000000..3e9134b470c
--- /dev/null
+++ b/test/parallel/test-preload-worker.js
@@ -0,0 +1,10 @@
+'use strict';
+
+const common = require('../common');
+const fixtures = require('../common/fixtures');
+const worker = fixtures.path('worker-preload.js');
+const { exec } = require('child_process');
+const kNodeBinary = process.argv[0];
+
+
+exec(`"${kNodeBinary}" -r "${worker}" -pe "1+1"`, common.mustSucceed());