Merge pull request #58 from bnoordhuis/fix56

fix: Fix `takeHeapSnapshot()` truncation bug

Author: jkrems

lib/internal/inspect_repl.js

@@ -900,10 +900,8 @@ function createRepl(inspector) {
         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 {
@@ -913,13 +911,18 @@ function createRepl(inspector) {
           function onChunk({ chunk }) {
             sizeWritten += chunk.length;
             writer.write(chunk);
-            print(`Writing snapshot: ${sizeWritten}/${totalSize}`, true);
-            if (sizeWritten >= totalSize) {
-              writer.end();
+            print(`Writing snapshot: ${sizeWritten}`, true);
+          }
+          function onResolve() {
+            writer.end(() => {
               teardown();
               print(`Wrote snapshot: ${absoluteFile}`);
               resolve();
-            }
+            });
+          }
+          function onReject(error) {
+            teardown();
+            reject(error);
           }
           function teardown() {
             HeapProfiler.removeListener(
@@ -932,10 +935,7 @@ function createRepl(inspector) {
 
           print('Heap snapshot: 0/0', true);
           HeapProfiler.takeHeapSnapshot({ reportProgress: true })
-            .then(null, (error) => {
-              teardown();
-              reject(error);
-            });
+            .then(onResolve, onReject);
         });
       },
 

test/cli/heap-profiler.test.js

@@ -0,0 +1,34 @@
+'use strict';
+const { test } = require('tap');
+const { readFileSync, unlinkSync } = require('fs');
+
+const startCLI = require('./start-cli');
+const filename = 'node.heapsnapshot';
+
+function cleanup() {
+  try {
+    unlinkSync(filename);
+  } catch (_) {
+    // Ignore.
+  }
+}
+
+cleanup();
+
+test('Heap profiler take snapshot', (t) => {
+  const cli = startCLI(['examples/empty.js']);
+
+  function onFatal(error) {
+    cli.quit();
+    throw error;
+  }
+
+  // Check that the snapshot is valid JSON.
+  return cli.waitForInitialBreak()
+    .then(() => cli.waitForPrompt())
+    .then(() => cli.command('takeHeapSnapshot()'))
+    .then(() => JSON.parse(readFileSync(filename, 'utf8')))
+    .then(() => cleanup())
+    .then(() => cli.quit())
+    .then(null, onFatal);
+});