cli: add --max-heap-size option

tannal · aduh95 · commit 62d2cd473b65 · 2026-03-25T10:40:14.000+01:00
PR-URL: #58708 Reviewed-By: Gürgün Dayıoğlu <hey@gurgun.day>
diff --git a/doc/api/cli.md b/doc/api/cli.md
@@ -3741,6 +3741,7 @@ V8 options that are allowed are:
 * `--expose-gc`
 * `--interpreted-frames-native-stack`
 * `--jitless`
+* `--max-heap-size`
 * `--max-old-space-size`
 * `--max-semi-space-size`
 * `--perf-basic-prof-only-functions`
@@ -4099,6 +4100,12 @@ documented here:
 
 ### `--jitless`
 
+### `--max-heap-size`
+
+Specifies the maximum heap size (in megabytes) for the process.
+
+This option is typically used to limit the amount of memory the process can use for its JavaScript heap.
+
 <!-- Anchor to make sure old links find a target -->
 
 <a id="--max-old-space-sizesize-in-megabytes"></a>
diff --git a/src/node_options.cc b/src/node_options.cc
@@ -1228,6 +1228,7 @@ PerIsolateOptionsParser::PerIsolateOptionsParser(
             "help system profilers to translate JavaScript interpreted frames",
             V8Option{},
             kAllowedInEnvvar);
+  AddOption("--max-heap-size", "", V8Option{}, kAllowedInEnvvar);
   AddOption("--max-old-space-size", "", V8Option{}, kAllowedInEnvvar);
   AddOption("--max-old-space-size-percentage",
             "set V8's max old space size as a percentage of available memory "
diff --git a/test/common/v8-max-heap-size-option.js b/test/common/v8-max-heap-size-option.js
@@ -0,0 +1,49 @@
+'use strict';
+
+const assert = require('assert');
+const { spawnSync } = require('child_process');
+const path = require('path');
+const fs = require('fs');
+const tmpdir = require('./tmpdir');
+
+const testScript = `
+  const v8 = require('v8');
+  const stats = v8.getHeapStatistics();
+  const maxHeapSizeMB = Math.round(stats.heap_size_limit / 1024 / 1024);
+  console.log(maxHeapSizeMB);
+`;
+
+tmpdir.refresh();
+const scriptPath = path.join(tmpdir.path, 'heap-limit-test.js');
+fs.writeFileSync(scriptPath, testScript);
+
+const child = spawnSync(
+  process.execPath,
+  [scriptPath],
+  {
+    encoding: 'utf8',
+    env: {
+      ...process.env,
+      NODE_OPTIONS: '--max-heap-size=750',
+    },
+  },
+);
+
+assert.strictEqual(
+  child.status,
+  0,
+  [
+    `Child process did not exit cleanly.`,
+    `  Exit code: ${child.status}`,
+    child.stderr ? `  Stderr: ${child.stderr.toString()}` : '',
+    child.stdout ? `  Stdout: ${child.stdout.toString()}` : '',
+  ].filter(Boolean).join('\n'),
+);
+const output = child.stdout.trim();
+const heapLimit = Number(output);
+
+assert.strictEqual(
+  heapLimit,
+  750,
+  `max heap size is ${heapLimit}MB, expected 750MB`,
+);
