Automatically debug memory leaks.

BLeak automatically locates, ranks, and diagnoses memory leaks in client-side web applications. Works on , , and .

Install today:

$ npm install -g bleak-detector

Builds on and requires MITMProxy 2.0 (3.0 support coming soon!):

$ pip install mitmproxy==2.0.2

1. Write a configuration file.

The configuration file specifies a loop of screens (or "visual states") that BLeak will run through.

exports.url = "http://mysite.example.org/";
// Each item is 'visual state'.
// 'check' returns 'true' if the web
// application is in the visual state,
// and 'next' advances to the next
// visual state.
exports.loop = [{
// Check that inbox view has loaded,
// with a full email listing.
check: function() {
let inboxList = $('#inbox');
return inboxList.length > 0;
},
// Click on the first email.
next: function() {
$('#inbox').click();
}
}, {
// Check that this email has loaded.
check: function() {
let subject = $("#subject").text();
return subject === "Test Email";
},
// Return to the inbox view
// to close the loop.
next: function() {
let menuBar = $('#menu');
// First item is the inbox button.
menuBar[0].click();
}
}];
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Code in the configuration file executes in the context of the web page, so you can interact with JavaScript running on the webpage.

Optional attributes specify one-time login and setup procedures to enter the loop.

Learn more »

2. Run BLeak.

Using the configuration file, BLeak runs your web application in a loop through the specified visual states and looks for memory leaks.

$ bleak run --config my.config.js \
  --out bleak_output

Specifically, BLeak looks for objects that are exhibiting sustained growth.

Read the paper (PLDI 2018, preprint) »

3. View results.

The BLeak viewer displays all of the information needed to debug each memory leak.

$ bleak viewer

Specifically, the viewer displays the following information:

  • The magnitude of heap growth over loop round trips
  • The web application's source code, with problematic program statements highlighted
  • For each leak:
    • Human-readable heap paths at which the growing object is located
    • A LeakShare score that represents the impact/importance of the memory leak
    • Stack traces that point to the code responsible for growing the object

Live demo »


BLeak finds leaks in real web applications.

BLeak found and diagnosed over 50 memory leaks in dozens of libraries and applications, and can do so without access to unminified/unobfuscated source code. See our paper for a full listing.