cluster: fix inspector port assignment

Make sure that inspector ports in cluster are inside the valid range:
`[1024, 65535]`.
Fixes flaky `test-inspector-port-zero-cluster`.

PR-URL: #18696
Fixes: #18303
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

lib/internal/cluster/master.js

@@ -14,6 +14,7 @@ const intercom = new EventEmitter();
 const SCHED_NONE = 1;
 const SCHED_RR = 2;
 const { isLegalPort } = require('internal/net');
+const [ minPort, maxPort ] = [ 1024, 65535 ];
 
 module.exports = cluster;
 
@@ -119,6 +120,8 @@ function createWorkerProcess(id, env) {
  }
  } else {
  inspectPort = process.debugPort + debugPortOffset;
+ if (inspectPort > maxPort)
+ inspectPort = inspectPort - maxPort + minPort - 1;
  debugPortOffset++;
  }
 

test/sequential/test-inspector-port-cluster.js

@@ -24,6 +24,16 @@ function testRunnerMain() {
  workers: [{ expectedPort: 9230 }]
  });
 
+ spawnMaster({
+ execArgv: ['--inspect=65534'],
+ workers: [
+ { expectedPort: 65535 },
+ { expectedPort: 1024 },
+ { expectedPort: 1025 },
+ { expectedPort: 1026 }
+ ]
+ });
+
  let port = debuggerPort + offset++ * 5;
 
  spawnMaster({

test/sequential/test-inspector-port-zero-cluster.js

@@ -30,16 +30,14 @@ function serialFork() {
 if (cluster.isMaster) {
  Promise.all([serialFork(), serialFork(), serialFork()])
  .then(common.mustCall((ports) => {
- ports.push(process.debugPort);
- ports.sort();
+ ports.splice(0, 0, process.debugPort);
  // 4 = [master, worker1, worker2, worker3].length()
  assert.strictEqual(ports.length, 4);
  assert(ports.every((port) => port > 0));
  assert(ports.every((port) => port < 65536));
- // Ports should be consecutive.
- assert.strictEqual(ports[0] + 1, ports[1]);
- assert.strictEqual(ports[1] + 1, ports[2]);
- assert.strictEqual(ports[2] + 1, ports[3]);
+ assert.strictEqual(ports[0] === 65535 ? 1024 : ports[0] + 1, ports[1]);
+ assert.strictEqual(ports[1] === 65535 ? 1024 : ports[1] + 1, ports[2]);
+ assert.strictEqual(ports[2] === 65535 ? 1024 : ports[2] + 1, ports[3]);
  }))
  .catch(
  (err) => {