I’m building a web scraping application that needs to handle multiple concurrent requests. I’ve tried several headless browser solutions but keep running into threading issues or poor JavaScript handling.
So far I’ve tested:
HtmlUnit - threading works but JavaScript execution is unreliable
QtWebKit with QWebPage - can’t instantiate from worker threads
PhantomJS - requires spawning separate processes which creates overhead
Awesomium - has thread safety limitations
I need recommendations for headless browsers that support both solid JavaScript rendering and can safely create new instances across multiple threads. The programming language doesn’t matter to me as long as it meets these requirements.
I’ve had great success with Selenium Grid + headless Chrome for concurrent scraping. Each WebDriver runs independently, so you can spin up multiple instances across threads without them interfering with each other. JavaScript execution is rock solid since you’re using the actual Chrome engine, not some emulation. Memory usage gets heavy with lots of concurrent instances, but the stability makes it worth it. I usually limit instances based on available RAM - I’ve run 20+ parallel sessions without major problems. Setup takes a bit more work than single-threaded solutions, but the threading safety is excellent.
Playwright’s perfect for this. It crushes concurrency since each browser context runs isolated - I’ve had 50+ workers going without any threading nightmares. JavaScript execution is solid because it uses actual browser engines (Chromium, Firefox, or WebKit). Best part? No manual process management like PhantomJS. The API’s clean, contexts run independently across threads, and memory usage beats spinning up multiple Chrome instances. Plus it’s actively maintained, unlike those older tools you’ve tried.
puppeteer is pretty good! it runs each browser in its own process, so no threading issues. plus, chrome’s js engine is solid. there’s a bit of overhead but definitely more stable than phantomjs. give it a shot!