Heritrix 3.0/3.1 introduces the ability to run multiple jobs simultaneously on the same crawler instance.  In Heritrix 1.x, only one job could be run at a time.  Other jobs were queued behind the running job. The only limit effecting the number of jobs that can be run simultaneously in Heritrix 3.0/3.1 is the amount of memory allocated to the Java heap.  If many crawls are run, the Java heap may at some point be exhausted. This will result in an OutOfMemory error that will abort the running crawls.

Once a crawl job has been created and properly configured it can be run.  To start a crawl the user must go to the job page by clicking the specific job in the WUI. 

job.png (image/png)
job.png (image/png)