feat: Support CPU & heap profiles

Author: Jan Krems

lib/_inspect.js

@@ -24,6 +24,7 @@ const Buffer = require('buffer').Buffer;
 const { spawn } = require('child_process');
 const crypto = require('crypto');
 const { EventEmitter } = require('events');
+const FS = require('fs');
 const http = require('http');
 const Path = require('path');
 const Repl = require('repl');
@@ -585,7 +586,7 @@ function createRepl(inspector) {
     });
   }
 
-  const { Debugger, Runtime } = inspector;
+  const { Debugger, HeapProfiler, Profiler, Runtime } = inspector;
 
   let repl; // eslint-disable-line prefer-const
 
@@ -676,6 +677,31 @@ function createRepl(inspector) {
     }
   }
 
+  const profiles = [];
+  class Profile {
+    constructor(data) {
+      this.data = data;
+    }
+
+    static createAndRegister({ profile }) {
+      const p = new Profile(profile);
+      profiles.push(p);
+      return p;
+    }
+
+    [util.inspect.custom](depth, { stylize }) {
+      const { startTime, endTime } = this.data;
+      return stylize(`[Profile ${endTime - startTime}μs]`, 'special');
+    }
+
+    save(filename = 'node.cpuprofile') {
+      const absoluteFile = Path.resolve(filename);
+      const json = JSON.stringify(this.data);
+      FS.writeFileSync(absoluteFile, json);
+      print('Saved profile to ' + absoluteFile);
+    }
+  }
+
   class SourceSnippet {
     constructor(location, delta, scriptSource) {
       Object.assign(this, location);
@@ -1113,6 +1139,14 @@ function createRepl(inspector) {
     }
   });
 
+  Profiler.on('consoleProfileFinished', ({ profile }) => {
+    Profile.createAndRegister({ profile });
+    print([
+      'Captured new CPU profile.',
+      `Access it with profiles[${profiles.length - 1}]`
+    ].join('\n'));
+  });
+
   function initializeContext(context) {
     inspector.domainNames.forEach((domain) => {
       Object.defineProperty(context, domain, {
@@ -1176,6 +1210,62 @@ function createRepl(inspector) {
         return evalInCurrentContext(expr);
       },
 
+      get profile() {
+        return Profiler.start();
+      },
+
+      get profileEnd() {
+        return Profiler.stop()
+          .then(Profile.createAndRegister);
+      },
+
+      get profiles() {
+        return profiles;
+      },
+
+      takeHeapSnapshot(filename = 'node.heapsnapshot') {
+        return new Promise((resolve, reject) => {
+          const absoluteFile = Path.resolve(filename);
+          const writer = FS.createWriteStream(absoluteFile);
+          let totalSize;
+          let sizeWritten = 0;
+          function onProgress({ done, total, finished }) {
+            totalSize = total;
+            if (finished) {
+              print('Heap snaphost prepared.');
+            } else {
+              print(`Heap snapshot: ${done}/${total}`, true);
+            }
+          }
+          function onChunk({ chunk }) {
+            sizeWritten += chunk.length;
+            writer.write(chunk);
+            print(`Writing snapshot: ${sizeWritten}/${totalSize}`, true);
+            if (sizeWritten >= totalSize) {
+              writer.end();
+              teardown();
+              print(`Wrote snapshot: ${absoluteFile}`);
+              resolve();
+            }
+          }
+          function teardown() {
+            HeapProfiler.removeListener(
+              'reportHeapSnapshotProgress', onProgress);
+            HeapProfiler.removeListener('addHeapSnapshotChunk', onChunk);
+          }
+
+          HeapProfiler.on('reportHeapSnapshotProgress', onProgress);
+          HeapProfiler.on('addHeapSnapshotChunk', onChunk);
+
+          print('Heap snapshot: 0/0', true);
+          HeapProfiler.takeHeapSnapshot({ reportProgress: true })
+            .then(null, (error) => {
+              teardown();
+              reject(error);
+            });
+        });
+      },
+
       get watchers() {
         return watchers();
       },
@@ -1374,7 +1464,7 @@ class NodeInspector {
 
     this.client = new ProtocolClient(options.port, options.host);
 
-    this.domainNames = ['Debugger', 'Runtime'];
+    this.domainNames = ['Debugger', 'HeapProfiler', 'Profiler', 'Runtime'];
     this.domainNames.forEach((domain) => {
       this[domain] = createAgentProxy(domain, this.client);
     });

test/cli/profile.test.js

@@ -3,6 +3,10 @@ const { test } = require('tap');
 
 const startCLI = require('./start-cli');
 
+function delay(ms) {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
 test('profiles', (t) => {
   const cli = startCLI(['examples/empty.js']);
 
@@ -18,8 +22,10 @@ test('profiles', (t) => {
       t.match(cli.output, 'undefined');
     })
     .then(() => cli.command('exec console.profileEnd()'))
+    .then(() => delay(250))
     .then(() => {
       t.match(cli.output, 'undefined');
+      t.match(cli.output, 'Captured new CPU profile.');
     })
     .then(() => cli.quit())
     .then(null, onFatal);