[VFS-294] NullPointerException in FtpFileObject.getChildFile()

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0
• Fix Version/s: 2.3
• Assignee: Unassigned
• Reporter: Johannes Scharf
• Created: 08/Jan/10 13:03
• Updated: 20/Nov/18 21:31
• Resolved: 20/Nov/18 21:31

Description

During my efforts to find a solution for VFS-293 I've discovered another bug regarding threadsafety.
It seems that FtpFileObject is at least not fully threadsafe. When a FtpFileObject is accessed by multiple threads from time to time closing the OutputStream for a file fails with a NullPointerException.

Stacktrace:

 org.apache.commons.vfs.FileSystemException: Could not close the output stream for file "ftp://localhost/spring-framework-2.5.5/dist/resources/spring-jms-2.5.xsd".
	at org.apache.commons.vfs.provider.DefaultFileContent$FileContentOutputStream.close(DefaultFileContent.java:599)
	at at.js.jtransporter.transporter.VFSTransporter$VFSOutputStream.close(VFSTransporter.java:219)
	at at.js.jtransporter.util.Utils.close(Utils.java:40)
	at at.js.jtransporter.worker.resource.ResourceWorker.createFile(ResourceWorker.java:108)
	at at.js.jtransporter.worker.resource.ResourceWorker.processJob(ResourceWorker.java:52)
	at at.js.jtransporter.worker.AbstractRunnableWorker.run(AbstractRunnableWorker.java:82)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
	at java.lang.Thread.run(Thread.java:619)
Caused by: org.apache.commons.vfs.FileSystemException: Could not close the output stream for file "ftp://localhost/spring-framework-2.5.5/dist/resources/spring-jms-2.5.xsd".
	at org.apache.commons.vfs.provider.DefaultFileContent$FileContentOutputStream.onClose(DefaultFileContent.java:620)
	at org.apache.commons.vfs.util.MonitorOutputStream.close(MonitorOutputStream.java:63)
	at org.apache.commons.vfs.provider.DefaultFileContent$FileContentOutputStream.close(DefaultFileContent.java:595)
	... 8 more
Caused by: java.lang.NullPointerException
	at org.apache.commons.vfs.provider.ftp.FtpFileObject.getChildFile(FtpFileObject.java:106)
	at org.apache.commons.vfs.provider.ftp.FtpFileObject.getInfo(FtpFileObject.java:181)
	at org.apache.commons.vfs.provider.ftp.FtpFileObject.onChange(FtpFileObject.java:269)
	at org.apache.commons.vfs.provider.AbstractFileObject.endOutput(AbstractFileObject.java:1325)
	at org.apache.commons.vfs.provider.DefaultFileContent.endOutput(DefaultFileContent.java:459)
	at org.apache.commons.vfs.provider.DefaultFileContent.access$200(DefaultFileContent.java:44)
	at org.apache.commons.vfs.provider.DefaultFileContent$FileContentOutputStream.onClose(DefaultFileContent.java:616)
	... 10 more