Ultimately it depends on how you write the Mapper.map method. The framework supports a MultithreadedMapRunner which lets you set the number of threads running your map method simultaneously. Chapter 5 of my book covers this.
On Wed, May 13, 2009 at 11:10 PM, Shengkai Zhu <geniusj...@gmail.com> wrote: > Each mapper instance will be executed in separate JVM. > > On Thu, May 14, 2009 at 2:04 PM, imcaptor <imcap...@gmail.com> wrote: > > > Dear all: > > > > Any one knows Is Mapper's map method thread safe? > > Thank you! > > > > imcaptor > > > > > > -- > > 朱盛凯 > > Jash Zhu > > 复旦大学软件学院 > > Software School, Fudan University > -- Alpha Chapters of my book on Hadoop are available http://www.apress.com/book/view/9781430219422 www.prohadoopbook.com a community for Hadoop Professionals
