After upgrading to 1.517 I was hit by a problem with fingerprinting. I am not sure if it is core related please reassign if appropriate.

I am fingerprinting a file in the upstream build process, pack several 100 files and assembles via scm clone workspace plugin and start about 50 unit test jobs on a bunch of slaves. After testing the downstream unit test project fingerprints the same file to be able to track the changes of the upstream project.

With 1.517 now it happens that the fingerprinting seems to hang so that the workspace can not be cleaned up after testing:

17:35:31 Recording fingerprints
17:35:31 No emails were triggered.
17:35:31
17:35:31 Deleting project workspace...
17:35:49 Cannot delete workspace: java.nio.file.FileSystemException: C:\WS\SscuMimoVar13Tests\ContestContinuous\contest_sw\Bin\Debug\CommonTypes.dll: The process cannot access the file because it is being used by another process.
17:35:49
17:35:49 Option not to fail the build is turned on, so let's continue
17:35:49 Notifying upstream projects of job completion
17:35:49 Finished: SUCCESS

Starting the next test some time later on the same machine leads to a failure because the old workspace can not be deleted because the file to fingerprint is still "in use by another process". Downgrading to 1.516 fixes the problem for me (but I had to restart all the slave Services). The problem also occured on my master, it was not related to slaves only.

17:36:11 Started by upstream project "ContestContinuous" build number 16910
17:36:11 originally caused by:
17:36:11 Started by an SCM change
17:36:11 [EnvInject] - Loading node environment variables.
17:36:11 Building remotely on 1SP1-SLAVE8 in workspace C:\WS\SscuMimoVar13Tests
17:36:11 hudson.util.IOException2: remote file operation failed: C:\WS\SscuMimoVar13Tests at hudson.remoting.Channel@191b66bf:1SP1-SLAVE8
17:36:11 at hudson.FilePath.act(FilePath.java:901)
17:36:11 at hudson.FilePath.act(FilePath.java:878)
17:36:11 at hudson.FilePath.deleteContents(FilePath.java:1050)
17:36:11 at hudson.plugins.cloneworkspace.CloneWorkspaceSCM.checkout(CloneWorkspaceSCM.java:145)
17:36:11 at hudson.model.AbstractProject.checkout(AbstractProject.java:1369)
17:36:11 at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:676)
17:36:11 at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:88)
17:36:11 at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:581)
17:36:11 at hudson.model.Run.execute(Run.java:1576)
17:36:11 at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
17:36:11 at hudson.model.ResourceController.execute(ResourceController.java:88)
17:36:11 at hudson.model.Executor.run(Executor.java:241)
17:36:11 Caused by: java.nio.file.FileSystemException: C:\WS\SscuMimoVar13Tests\ContestContinuous\contest_sw\Bin\Debug\CommonTypes.dll: The process cannot access the file because it is being used by another process.
17:36:11
17:36:11 at sun.nio.fs.WindowsException.translateToIOException(Unknown Source)
17:36:11 at sun.nio.fs.WindowsException.rethrowAsIOException(Unknown Source)
17:36:11 at sun.nio.fs.WindowsException.rethrowAsIOException(Unknown Source)
17:36:11 at sun.nio.fs.WindowsFileSystemProvider.implDelete(Unknown Source)
17:36:11 at sun.nio.fs.AbstractFileSystemProvider.delete(Unknown Source)
17:36:11 at java.nio.file.Files.delete(Unknown Source)
17:36:11 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
17:36:11 at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
17:36:11 at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
17:36:11 at java.lang.reflect.Method.invoke(Unknown Source)
17:36:11 at hudson.Util.deleteFile(Util.java:237)
17:36:11 at hudson.Util.deleteRecursive(Util.java:305)
17:36:11 at hudson.Util.deleteContentsRecursive(Util.java:202)
17:36:11 at hudson.Util.deleteRecursive(Util.java:296)
17:36:11 at hudson.Util.deleteContentsRecursive(Util.java:202)
17:36:11 at hudson.Util.deleteRecursive(Util.java:296)
17:36:11 at hudson.Util.deleteContentsRecursive(Util.java:202)
17:36:11 at hudson.Util.deleteRecursive(Util.java:296)
17:36:11 at hudson.Util.deleteContentsRecursive(Util.java:202)
17:36:11 at hudson.Util.deleteRecursive(Util.java:296)
17:36:11 at hudson.Util.deleteContentsRecursive(Util.java:202)
17:36:11 at hudson.FilePath$12.invoke(FilePath.java:1053)
17:36:11 at hudson.FilePath$12.invoke(FilePath.java:1050)
17:36:11 at hudson.FilePath$FileCallableWrapper.call(FilePath.java:2388)
17:36:11 at hudson.remoting.UserRequest.perform(UserRequest.java:118)
17:36:11 at hudson.remoting.UserRequest.perform(UserRequest.java:48)
17:36:11 at hudson.remoting.Request$2.run(Request.java:326)
17:36:11 at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72)
17:36:11 at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
17:36:11 at java.util.concurrent.FutureTask.run(Unknown Source)
17:36:11 at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
17:36:11 at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
17:36:11 at hudson.remoting.Engine$1$1.run(Engine.java:58)
17:36:11 at java.lang.Thread.run(Unknown Source)

Here on the master:
17:01:28 Started by upstream project "ContestContinuous" build number 16906
17:01:28 originally caused by:
17:01:28 Started by an SCM change
17:01:28 [EnvInject] - Loading node environment variables.
17:01:28 Building on master in workspace D:\WS\ScenarioServiceSscuMimoTests
17:01:28 java.nio.file.FileSystemException: D:\WS\ScenarioServiceSscuMimoTests\ContestContinuous\contest_sw\Bin\Debug\CommonTypes.dll: The process cannot access the file because it is being used by another process.
17:01:28