When the Github Org Folder Scan runs and tries to clean up old branch and PR builds, we see errors like ".nfsXXXXX: Device or Resource Busy".  See stack trace below:

FATAL: Failed to recompute children of Bluton Pull Requests » bluton
jenkins.util.io.CompositeIOException: Unable to delete '/opt/apache/.jenkins/jobs/Bluton Pull Requests/jobs/bluton/branches/Docker123'. Tried 3 times (of a maximum of 3) waiting 0.1 sec between attempts.
{{ at jenkins.util.io.PathRemover.forceRemoveRecursive(PathRemover.java:95)}}
{{ at hudson.Util.deleteRecursive(Util.java:294)}}
{{ at hudson.Util.deleteRecursive(Util.java:283)}}
{{ at hudson.model.AbstractItem.performDelete(AbstractItem.java:792)}}
{{ at org.jenkinsci.plugins.workflow.job.WorkflowJob.performDelete(WorkflowJob.java:652)}}
{{ at hudson.model.AbstractItem.delete(AbstractItem.java:776)}}
{{ at hudson.model.Job.delete(Job.java:677)}}
{{ at com.cloudbees.hudson.plugins.folder.computed.ComputedFolder.updateChildren(ComputedFolder.java:290)}}
{{ at com.cloudbees.hudson.plugins.folder.computed.FolderComputation.run(FolderComputation.java:165)}}
{{ at jenkins.branch.MultiBranchProject$BranchIndexing.run(MultiBranchProject.java:1025)}}
{{ at hudson.model.ResourceController.execute(ResourceController.java:97)}}
{{ at hudson.model.Executor.run(Executor.java:429)}}
jenkins.util.io.CompositeIOException: Unable to remove file /opt/apache/.jenkins/jobs/Bluton Pull Requests/jobs/bluton/branches/Docker123/builds/41/.nfs00000000080f52850000009d
{{ at jenkins.util.io.PathRemover.removeOrMakeRemovableThenRemove(PathRemover.java:248)}}
{{ at jenkins.util.io.PathRemover.tryRemoveFile(PathRemover.java:201)}}
{{ at jenkins.util.io.PathRemover.tryRemoveRecursive(PathRemover.java:212)}}
{{ at jenkins.util.io.PathRemover.tryRemoveDirectoryContents(PathRemover.java:222)}}
{{ at jenkins.util.io.PathRemover.tryRemoveRecursive(PathRemover.java:211)}}
{{ at jenkins.util.io.PathRemover.tryRemoveDirectoryContents(PathRemover.java:222)}}
{{ at jenkins.util.io.PathRemover.tryRemoveRecursive(PathRemover.java:211)}}
{{ at jenkins.util.io.PathRemover.tryRemoveDirectoryContents(PathRemover.java:222)}}
{{ at jenkins.util.io.PathRemover.tryRemoveRecursive(PathRemover.java:211)}}
{{ at jenkins.util.io.PathRemover.forceRemoveRecursive(PathRemover.java:92)}}
{{ at hudson.Util.deleteRecursive(Util.java:294)}}
{{ at hudson.Util.deleteRecursive(Util.java:283)}}
{{ at hudson.model.AbstractItem.performDelete(AbstractItem.java:792)}}
{{ at org.jenkinsci.plugins.workflow.job.WorkflowJob.performDelete(WorkflowJob.java:652)}}
{{ at hudson.model.AbstractItem.delete(AbstractItem.java:776)}}
{{ at hudson.model.Job.delete(Job.java:677)}}
{{ at com.cloudbees.hudson.plugins.folder.computed.ComputedFolder.updateChildren(ComputedFolder.java:290)}}
{{ at com.cloudbees.hudson.plugins.folder.computed.FolderComputation.run(FolderComputation.java:165)}}
{{ at jenkins.branch.MultiBranchProject$BranchIndexing.run(MultiBranchProject.java:1025)}}
{{ at hudson.model.ResourceController.execute(ResourceController.java:97)}}
{{ at hudson.model.Executor.run(Executor.java:429)}}
java.nio.file.FileSystemException: /opt/apache/.jenkins/jobs/Bluton Pull Requests/jobs/bluton/branches/Docker123/builds/41/.nfs00000000080f52850000009d: Device or resource busy
{{ at sun.nio.fs.UnixException.translateToIOException(UnixException.java:91)}}
{{ at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)}}
{{ at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)}}
{{ at sun.nio.fs.UnixFileSystemProvider.implDelete(UnixFileSystemProvider.java:244)}}
{{ at sun.nio.fs.AbstractFileSystemProvider.deleteIfExists(AbstractFileSystemProvider.java:108)}}
{{ at java.nio.file.Files.deleteIfExists(Files.java:1165)}}
{{ at jenkins.util.io.PathRemover.removeOrMakeRemovableThenRemove(PathRemover.java:233)}}
{{ at jenkins.util.io.PathRemover.tryRemoveFile(PathRemover.java:201)}}
{{ at jenkins.util.io.PathRemover.tryRemoveRecursive(PathRemover.java:212)}}
{{ at jenkins.util.io.PathRemover.tryRemoveDirectoryContents(PathRemover.java:222)}}
{{ at jenkins.util.io.PathRemover.tryRemoveRecursive(PathRemover.java:211)}}
{{ at jenkins.util.io.PathRemover.tryRemoveDirectoryContents(PathRemover.java:222)}}
{{ at jenkins.util.io.PathRemover.tryRemoveRecursive(PathRemover.java:211)}}
{{ at jenkins.util.io.PathRemover.tryRemoveDirectoryContents(PathRemover.java:222)}}
{{ at jenkins.util.io.PathRemover.tryRemoveRecursive(PathRemover.java:211)}}
{{ at jenkins.util.io.PathRemover.forceRemoveRecursive(PathRemover.java:92)}}
{{ at hudson.Util.deleteRecursive(Util.java:294)}}
{{ at hudson.Util.deleteRecursive(Util.java:283)}}
{{ at hudson.model.AbstractItem.performDelete(AbstractItem.java:792)}}
{{ at org.jenkinsci.plugins.workflow.job.WorkflowJob.performDelete(WorkflowJob.java:652)}}
{{ at hudson.model.AbstractItem.delete(AbstractItem.java:776)}}
{{ at hudson.model.Job.delete(Job.java:677)}}
{{ at com.cloudbees.hudson.plugins.folder.computed.ComputedFolder.updateChildren(ComputedFolder.java:290)}}
{{ at com.cloudbees.hudson.plugins.folder.computed.FolderComputation.run(FolderComputation.java:165)}}
{{ at jenkins.branch.MultiBranchProject$BranchIndexing.run(MultiBranchProject.java:1025)}}
{{ at hudson.model.ResourceController.execute(ResourceController.java:97)}}
{{ at hudson.model.Executor.run(Executor.java:429)}}

When I go look at the open files on the Jenkins java process, I see a bunch of .nfs files which appear to be all related to EC2 instances managed by the EC2 Plugin.

root@foo:/proc/15266/fd# ls -l | grep -i \.nfs
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 101 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-03fd7b1343b0782b8)/.nfs00000000080a6a830000009a
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 108 -> /srv/jenkins/jobs/Bluton Pull Requests/jobs/bluton/branches/Docker123/builds/41/.nfs00000000080f52850000009d
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 109 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-07baa1e7f3d95a94e)/.nfs00000000080ae75e00000095
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 110 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-019098927c3f4c8a9)/.nfs000000000805bd9000000097
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 1413 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-03460b045be5a9faa)/.nfs000000000807291b00000088
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 1423 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-0cfbcbfdf761f9d07)/.nfs000000000807599500000094
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 1450 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-029f40ef47d320089)/.nfs000000000807203f00000087
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 1454 -> /srv/jenkins/jobs/Bluton Pull Requests/jobs/tools/branches/PR-799/builds/24/.nfs0000000008056f6500000092
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 1463 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-0cfbcbfdf761f9d07)/.nfs000000000807598f00000093
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 1487 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-05c354bbe104d7f4b)/.nfs0000000008017b5b00000090
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 1497 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-05f3b733d4a484bb1)/.nfs00000000080429ae0000008d
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 1536 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-0afc0ecc2e3f5e1f6)/.nfs00000000080752030000009b
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 1559 -> /srv/jenkins/jobs/FOO Org (synapse)/jobs/bluton/branches/TCAR12345-Bla.7k9tn5.onfiguration/builds/2/.nfs00000000080ae4fc000000a1
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 1562 -> /srv/jenkins/jobs/FOO Org (synapse)/jobs/bluton/branches/TCAR12345-Bla.7k9tn5.onfiguration/builds/2/.nfs00000000080ae4fd000000a2
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 66 -> /srv/jenkins/jobs/Bluton Pull Requests/jobs/tools/branches/PR-799/builds/24/.nfs0000000008081d1b00000091
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 67 -> /srv/jenkins/jobs/FOO Org (synapse)/jobs/bluton/branches/TCAR12345-Bla.7k9tn5.onfiguration/builds/1/.nfs00000000080b960d0000009f
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 70 -> /srv/jenkins/jobs/FOO Org (synapse)/jobs/bluton/branches/TCAR12345-Bla.7k9tn5.onfiguration/builds/1/.nfs00000000080b9611000000a0
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 79 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-07baa1e7f3d95a94e)/.nfs00000000080ae75800000096
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 83 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-05f3b733d4a484bb1)/.nfs00000000080429aa0000008e
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 84 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-019098927c3f4c8a9)/.nfs000000000805bd9600000098
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 87 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-019098927c3f4c8a9)/.nfs000000000805bd8f00000099
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 93 -> /srv/jenkins/logs/slaves/foo.bluton-large (i-00db25a98b6ffee4c)/.nfs00000000080b9e7800000089
l-wx------ 1 tomcat tomcat 64 Sep 4 08:58 95 -> /srv/jenkins/jobs/Bluton Pull Requests/jobs/bluton/branches/Docker123/builds/41/.nfs00000000080f52840000009c