1 files changed, 67 insertions, 0 deletions
diff --git a/test/pummel/test-fs-watch-system-limit.js b/test/pummel/test-fs-watch-system-limit.js
new file mode 100644
index 0000000000..8b9cb62ad0
--- /dev/null
+++ b/test/pummel/test-fs-watch-system-limit.js
@@ -0,0 +1,67 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const child_process = require('child_process');
+const fs = require('fs');
+const stream = require('stream');
+
+if (!common.isLinux)
+  common.skip('The fs watch limit is OS-dependent');
+if (!common.enoughTestCpu)
+  common.skip('This test is resource-intensive');
+
+try {
+  // Ensure inotify limit is low enough for the test to actually exercise the
+  // limit with small enough resources.
+  const limit = Number(
+    fs.readFileSync('/proc/sys/fs/inotify/max_user_watches', 'utf8'));
+  if (limit > 16384)
+    common.skip('inotify limit is quite large');
+} catch (e) {
+  if (e.code === 'ENOENT')
+    common.skip('the inotify /proc subsystem does not exist');
+  // Fail on other errors.
+  throw e;
+}
+
+const processes = [];
+const gatherStderr = new stream.PassThrough();
+gatherStderr.setEncoding('utf8');
+gatherStderr.setMaxListeners(Infinity);
+
+let finished = false;
+function spawnProcesses() {
+  for (let i = 0; i < 10; ++i) {
+    const proc = child_process.spawn(
+      process.execPath,
+      [ '-e',
+        `process.chdir(${JSON.stringify(__dirname)});
+        for (const file of fs.readdirSync('.'))
+          fs.watch(file, () => {});`
+      ], { stdio: ['inherit', 'inherit', 'pipe'] });
+    proc.stderr.pipe(gatherStderr);
+    processes.push(proc);
+  }
+
+  setTimeout(() => {
+    if (!finished && processes.length < 200)
+      spawnProcesses();
+  }, 100);
+}
+
+spawnProcesses();
+
+let accumulated = '';
+gatherStderr.on('data', common.mustCallAtLeast((chunk) => {
+  accumulated += chunk;
+  if (accumulated.includes('Error:') && !finished) {
+    assert(
+      accumulated.includes('ENOSPC: System limit for number ' +
+                           'of file watchers reached') ||
+      accumulated.includes('EMFILE: '),
+      accumulated);
+    console.log(`done after ${processes.length} processes, cleaning up`);
+    finished = true;
+    processes.forEach((proc) => proc.kill());
+  }
+}, 1));