Java Tip: When to use ForkJoinPool vs ExecutorService

The Fork/Join library introduced in Java 7 extends the existing Java concurrency package with support for hardware parallelism, a key feature of multicore systems. In this Java Tip Madalin Ilie demonstrates the performance impact of replacing the Java 6 ExecutorService class with Java 7’s ForkJoinPool in a web crawler application.

Web crawlers, also known as web spiders, are key to the success of search engines. These programs perpetually scan the web, gathering up millions of pages of data and sending it back to search-engine databases. The data is then indexed and processed algorithmically, resulting in faster, more accurate search results. While they are most famously used for search optimization, web crawlers also can be used for automated tasks such as link validation or finding and returning specific data (such as email addresses) in a collection of web pages.

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