doc: add inspector API example for heapdump

PR-URL: #26498 Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Richard Lau <[email protected]> Reviewed-By: Eugene Ostroukhov <[email protected]> Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]> Reviewed-By: James M Snell <[email protected]>
nodejs · Mar 14, 2019 · 5ad9929 · 5ad9929
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diff --git a/doc/api/inspector.md b/doc/api/inspector.md
@@ -154,10 +154,12 @@ to the run-time events.
 
 ## Example usage
 
+Apart from the debugger, various V8 Profilers are available through the DevTools
+protocol.
+
 ### CPU Profiler
 
-Apart from the debugger, various V8 Profilers are available through the DevTools
-protocol. Here's a simple example showing how to use the [CPU profiler][]:
+Here's an example showing how to use the [CPU Profiler][]:
 
 ```js
 const inspector = require('inspector');
@@ -180,8 +182,33 @@ session.post('Profiler.enable', () => {
 });
 ```
 
+### Heap Profiler
+
+Here's an example showing how to use the [Heap Profiler][]:
+
+```js
+const inspector = require('inspector');
+const fs = require('fs');
+const session = new inspector.Session();
+
+const fd = fs.openSync('profile.heapsnapshot', 'w');
+
+session.connect();
+
+session.on('HeapProfiler.addHeapSnapshotChunk', (m) => {
+  fs.writeSync(fd, m.params.chunk);
+});
+
+session.post('HeapProfiler.takeHeapSnapshot', null, (err, r) => {
+  console.log('Runtime.takeHeapSnapshot done:', err, r);
+  session.disconnect();
+  fs.closeSync(fd);
+});
+```
+
 [`'Debugger.paused'`]: https://chromedevtools.github.io/devtools-protocol/v8/Debugger#event-paused
 [`EventEmitter`]: events.html#events_class_eventemitter
 [`session.connect()`]: #inspector_session_connect
 [CPU Profiler]: https://chromedevtools.github.io/devtools-protocol/v8/Profiler
 [Chrome DevTools Protocol Viewer]: https://chromedevtools.github.io/devtools-protocol/v8/
+[Heap Profiler]: https://chromedevtools.github.io/devtools-protocol/v8/HeapProfiler
diff --git a/test/parallel/test-inspector-heapdump.js b/test/parallel/test-inspector-heapdump.js
@@ -0,0 +1,30 @@
+'use strict';
+const common = require('../common');
+
+common.skipIfInspectorDisabled();
+
+// Test that example code in doc/api/inspector.md continues to work with the V8
+// experimental API.
+
+const assert = require('assert');
+const inspector = require('inspector');
+const session = new inspector.Session();
+
+session.connect();
+
+const chunks = [];
+
+session.on('HeapProfiler.addHeapSnapshotChunk', (m) => {
+  chunks.push(m.params.chunk);
+});
+
+session.post('HeapProfiler.takeHeapSnapshot', null, common.mustCall((e, r) => {
+  assert.ifError(e);
+  assert.deepStrictEqual(r, {});
+  session.disconnect();
+
+  const profile = JSON.parse(chunks.join(''));
+  assert(profile.snapshot.meta);
+  assert(profile.snapshot.node_count > 0);
+  assert(profile.snapshot.edge_count > 0);
+}));