When the perforce server is unavailable the perforce polling launches a job anyways. We traced the issue to line 664 in perforceSCM.java

if (changeNumbers.isEmpty())

{ // Wierd, this shouldn't be! I suppose it could happen if the // view selects no files (e.g. //depot/non-existent-branch/...). // Just in case, let's try to build. return Boolean.TRUE; }

We have patched our local version of the plugin by changing the return value to false and the issue has been resolved in our case but I suspect additional checks may be required. In cases where the perforce server is down the changeNumbers is empty and the build is triggered. This results in a lot of build failures if the server goes down outside of normal business hours.