nodejs/node

Calling disconnect causes processes spawned by cluster module to exit too early

Open

#27,679 opened on May 13, 2019

View on GitHub
 (7 comments) (0 reactions) (0 assignees)JavaScript (35,535 forks)batch import
clusterhelp wantedstale

Repository metrics

Stars
 (117,218 stars)
PR merge metrics
 (Avg merge 18d 17h) (219 merged PRs in 30d)

Description

  • Version: 12.2.0 but could also reproduce on 10.15.3
  • Platform: Darwin 18.5.0 Darwin Kernel Version 18.5.0: Mon Mar 11 20:40:32 PDT 2019; root:xnu-4903.251.3~3/RELEASE_X86_64 x86_64
  • Subsystem:

Consider the following script:

const cluster = require('cluster');
const childProcess = require('child_process');

const useCluster = false;
const isMaster = useCluster ? cluster.isMaster : !process.argv.includes('worker');

if (isMaster) {
  if (useCluster) {
    cluster.fork(__filename);
  } else {
    childProcess.fork(__filename, ['worker']);
  }
} else {
  setTimeout(() => console.log('hi from worker'), 1000);
  process.disconnect();
}

When useCluster is true node exits immediately and nothing is printed to the console. When useCluster is false you see "hi from worker" logged after 1s and then node will exit which is the expected behavior. The documentation makes it sound like calling process.disconnect should only close the IPC channel between the master and worker process and should not cause either to exit early if there is still work to do.

Contributor guide

Research direction
Examine the cluster module's handling of process.disconnect, particularly how the master process reacts to IPC disconnection from a worker. Trace the code path in node/lib/internal/cluster/master.js and child process cleanup.
Tech stack
javascriptnodejs
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
Node.jscluster module basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65