如何以并行方式运行apache nutch不同的作业

I am using nutch 2.3. All jobs run one after other i.e. first generator, fetch, parse, index etc. I want to run some jobs simultaneously. I know some jobs cannot run in parallel but other can e.g parse job, dbupdate, indexjob should be run with fetch.I am using nutch 2.3. All jobs run one after ot