File conflicts when exporting multiple newspaper processes

[matthias-ronge]

Describe the bug
If several newspaper processes are exported from the process list (for example a whole year), the year processes are also exported for each issue. But several threads try to delete the existing parent process to replace it, but cannot find it anymore because it has already been deleted by another thread, and then abort.

To Reproduce

1. Select a larger amount of newspaper processes and then execute: export to dms
2. Crashes can be found in the task manager, and log file

org.apache.commons.io.IOExceptionList: /usr/local/kitodo/contents/Zeitung-1920
    at org.apache.commons.io.FileUtils.cleanDirectory(FileUtils.java:331)
    at org.apache.commons.io.FileUtils.deleteDirectory(FileUtils.java:1192)
    at org.kitodo.filemanagement.FileManagement.delete(FileManagement.java:141)
    at org.kitodo.production.services.file.FileService.delete(FileService.java:483)
    at org.kitodo.export.ExportDms.prepareExportLocation(ExportDms.java:230)
    at org.kitodo.export.ExportDms.startExport(ExportDms.java:207)
    at org.kitodo.export.ExportDms.startExport(ExportDms.java:159)
    at org.kitodo.production.helper.tasks.ExportDmsTask.run(ExportDmsTask.java:78)
Caused by: java.io.FileNotFoundException: File does not exist: /usr/local/kitodo/contents/Zeitung-1920/Zeitung-1920.xml
    at org.apache.commons.io.FileUtils.forceDelete(FileUtils.java:1349)
    at org.apache.commons.io.FileUtils.cleanDirectory(FileUtils.java:324)
    ... 7 more

Expected behavior

• When deleting, a file that has already been deleted is ignored, or
• exports of the same (parent) process are not done concurrently, or
• it would also be sufficient to export the parent process once to all children.

[henning-gerhardt]

A workaround for this is to limit the parallel execution of tasks inside the taskmanager to one (sequentiell work). As we use this since beginning (even in 2.x) I forgot to open a bug report as this issue still exists in 3.x :-(