🛑 Kill process trees on Linux (#2529)

Fixes jupyter-book/jupyter-book#2484

Author: rowanc1

.changeset/wide-shoes-laugh.md

@@ -0,0 +1,7 @@
+---
+'myst-cli-utils': patch
+'myst-execute': patch
+'myst-cli': patch
+---
+
+Kill process trees on linux when shutting down the application and jupyter servers

package-lock.json

@@ -33,7 +33,8 @@
   },
   "dependencies": {
     "chalk": "^5.2.0",
-    "pretty-hrtime": "^1.0.3"
+    "pretty-hrtime": "^1.0.3",
+    "tree-kill": "^1.2.2"
   },
   "devDependencies": {
     "@types/pretty-hrtime": "^1.0.1",

packages/myst-cli-utils/package.json

@@ -2,6 +2,7 @@ import util from 'util';
 import type { ExecOptions } from 'child_process';
 import child_process from 'child_process';
 import type { Logger } from './types.js';
+import treeKill from 'tree-kill';
 
 function execWrapper(
   command: string,
@@ -45,3 +46,19 @@ export function makeExecutable(
 ) {
   return util.promisify(makeExecWrapper(command, log, options)) as () => Promise<string>;
 }
+
+/**
+ * On Linux, child processes will not be terminated when attempting to kill their parent
+ * This function uses `tree-kill` to kill the process and all its child processes
+ */
+export function killProcessTree(process: child_process.ChildProcess) {
+  if (!process.pid) {
+    process.kill('SIGTERM');
+    return;
+  }
+  treeKill(process.pid, 'SIGTERM', (err) => {
+    if (err && process.pid) {
+      treeKill(process.pid, 'SIGKILL');
+    }
+  });
+}

packages/myst-cli-utils/src/exec.ts

@@ -7,7 +7,7 @@ export {
   createGitLogger,
   createNpmLogger,
 } from './logger.js';
-export { exec, makeExecutable } from './exec.js';
+export { exec, makeExecutable, killProcessTree } from './exec.js';
 export { clirun, tic } from './utils.js';
 export { isUrl } from './isUrl.js';
 export { Session, getSession } from './session.js';

packages/myst-cli-utils/src/index.ts

@@ -2,7 +2,7 @@ import chalk from 'chalk';
 import cors from 'cors';
 import express from 'express';
 import getPort, { portNumbers } from 'get-port';
-import { makeExecutable } from 'myst-cli-utils';
+import { makeExecutable, killProcessTree } from 'myst-cli-utils';
 import type child_process from 'child_process';
 import { nanoid } from 'nanoid';
 import { join } from 'node:path';
@@ -177,7 +177,7 @@ export async function startServer(
     start().catch((e) => session.log.debug(e));
   });
   appServer.stop = () => {
-    appServer.process.kill();
+    killProcessTree(appServer.process);
     server.stop();
   };
   return appServer;

packages/myst-cli/src/build/site/start.ts

@@ -3,6 +3,7 @@ import which from 'which';
 import { spawn } from 'node:child_process';
 import * as readline from 'node:readline';
 import type { ISession, Logger } from 'myst-cli-utils';
+import { killProcessTree } from 'myst-cli-utils';
 import chalk from 'chalk';
 
 export type JupyterServerSettings = Partial<ServerConnection.ISettings> & {
@@ -129,5 +130,5 @@ export async function launchJupyterServer(
   log.info(`🪐 ${chalk.greenBright('Jupyter server started')}\n   ${chalk.dim(url)}`);
 
   // Register settings destructor (to kill server)
-  return { ...settings, dispose: () => proc.kill() };
+  return { ...settings, dispose: () => killProcessTree(proc) };
 }