HTCondorWiki: Avoiding Black Holes

+This recipe is known to work with Condor 6.6
+
 A common problem is when some execute machine is misconfigured or broken in such a way that it still accepts Condor jobs, but can't run them correctly.  If jobs exit quickly on this kind of machine, it can quickly eat many of the jobs in your queue.  We call this a "black hole" machine.  To work around black hole machines, you can do the following in your job submit file:
 
 {code}
@@ -18,3 +20,12 @@
 {code}
 Requirements = target.name =!= LastMatchName1 && target.name =!= LastMatchName2 ...
 {endcode}
+
+One problem with this solution is that the LastMatchName attributes contain the slot number.  Usually, a black hole machine has problems across all slots in one machine.  The following recipe works for Condor 7.6 and later, but avoids the slot problem
+
+Add the following line to your submit file
+{code}
+job_machine_attrs = Machine
+job_machine_attrs_history_length = 5
+requirements = target.machine =!= MachineAttrMachine1 && target.machine =!= MachineAttrMachine2
+{endcode}