Hello,

I'd like to suggest a new feature - administrative lock which prevents new jobs from starting.

Use case: 1. I need to stop my galaxy server (to upgrade, to add new tool, to add new dbkey, etc). 2. I want to stop it in a friendly way, without killing running jobs, but not allow new jobs to start. 3. Once all the running jobs complete (and new jobs are not started), I can stop the server, fix it, and restart. 4. Restarting the server (and assuming jobs are tracked in the database), all the held jobs are started normally.

Code changes: 1. new administrative method ( job_lock() in ./lib/galaxy/web/controller/admin.py ) 2. new template ( ./templates/admin/job_lock.mako ) 3. job lock code in lib/galaxy/jobs/schedulingpolicy/roundrobin.py

I'm still testing this patch, but comments are welcomed. -gordon.