Importing via REST results in 'Unexpected end of ZLIB input stream' error

Issue Description

When importing via REST_v2, sometimes the following error occurs:

com.jaspersoft.jasperserver.export.service.ImportFailedException: Import failed. Reason: Nested error: org.exolab.castor.xml.MarshalException: org.xml.sax.SAXParseException; systemId: jar:file:/opt/5620sam/tomcat/webapps/jasperserver-pro/WEB-INF/lib/jasperserver-export-tool-6.3.0.jar!/com/jaspersoft/jasperserver/export/mapping/repository/Resource.xml; lineNumber: 1; columnNumber: 7; Premature end of file.{File: jar:file:/opt/5620sam/tomcat/webapps/jasperserver-pro/WEB-INF/lib/jasperserver-export-tool-6.3.0.jar!/com/jaspersoft/jasperserver/export/mapping/repository/Resource.xml; line: 1; column: 7}
at com.jaspersoft.jasperserver.export.service.impl.ImportExportServiceImpl.startImport(ImportExportServiceImpl.java:238)
at com.jaspersoft.jasperserver.export.service.impl.ImportExportServiceImpl.doImport(ImportExportServiceImpl.java:145)

...

ERROR ImportRunnable,pool-14-thread-2:81 - Import failed: 

com.jaspersoft.jasperserver.export.service.ImportFailedException: Import failed. Reason: Nested error: org.exolab.castor.xml.MarshalException: java.io.EOFException: Unexpected end of ZLIB input stream
at com.jaspersoft.jasperserver.export.service.impl.ImportExportServiceImpl.startImport(ImportExportServiceImpl.java:238)

Resolution

This error is usually the result of importing multiple zip files at once. Since REST calls have no innate blocking feature, when more than one zip file is imported then it is possible that the imports will collide while trying to write to the repository database. To avoid this, synchronize the imports so that one import waits for the next to finish, and so forth until all imports are completed.