[VFS-293] FtpFileSystem causes deadlock

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0
• Fix Version/s: 2.0
• Assignee: Unassigned
• Reporter: Johannes Scharf
• Created: 07/Jan/10 12:17
• Updated: 16/May/12 05:27
• Resolved: 23/Nov/10 00:30

Description

I use Commons VFS to access FTP from multiple threads. In each thread I create directories and copy files on the FTP server.
Nearly everytime when i run the program a deadlock occurs which causes all threads to hang. I've created a stacktrace with "jstack" which clearly shows where the deadlock is happening.

Stacktrace:

Found one Java-level deadlock:
=============================
"pool-1-thread-5":
  waiting to lock monitor 0x030813b4 (object 0x22f972e8, a org.apache.commons.vfs.provider.ftp.FtpFileSystem),
  which is held by "pool-1-thread-2"
"pool-1-thread-2":
  waiting to lock monitor 0x03082c7c (object 0x22f999e0, a java.lang.Object),
  which is held by "pool-1-thread-4"
"pool-1-thread-4":
  waiting to lock monitor 0x030813b4 (object 0x22f972e8, a org.apache.commons.vfs.provider.ftp.FtpFileSystem),
  which is held by "pool-1-thread-2"

Java stack information for the threads listed above:
===================================================
"pool-1-thread-5":
	at org.apache.commons.vfs.provider.AbstractFileSystem.streamOpened(AbstractFileSystem.java:569)
	- waiting to lock <0x22f972e8> (a org.apache.commons.vfs.provider.ftp.FtpFileSystem)
	at org.apache.commons.vfs.provider.DefaultFileContent.streamOpened(DefaultFileContent.java:92)
	at org.apache.commons.vfs.provider.DefaultFileContent.getOutputStream(DefaultFileContent.java:377)
	at at.js.jtransporter.transporter.VFSTransporter.createFile(VFSTransporter.java:119)
	at at.js.jtransporter.worker.resource.ResourceWorker.createFile(ResourceWorker.java:80)
	at at.js.jtransporter.worker.resource.ResourceWorker.processJob(ResourceWorker.java:51)
	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)
"pool-1-thread-2":
	at org.apache.commons.vfs.provider.ftp.FtpFileSystem.putClient(FtpFileSystem.java:137)
	- waiting to lock <0x22f999e0> (a java.lang.Object)
	at org.apache.commons.vfs.provider.ftp.FtpFileObject.doGetChildren(FtpFileObject.java:158)
	at org.apache.commons.vfs.provider.ftp.FtpFileObject.getChildFile(FtpFileObject.java:103)
	at org.apache.commons.vfs.provider.ftp.FtpFileObject.getInfo(FtpFileObject.java:181)
	at org.apache.commons.vfs.provider.ftp.FtpFileObject.refresh(FtpFileObject.java:208)
	at org.apache.commons.vfs.provider.AbstractFileSystem.resolveFile(AbstractFileSystem.java:319)
	- locked <0x22f972e8> (a org.apache.commons.vfs.provider.ftp.FtpFileSystem)
	at org.apache.commons.vfs.provider.AbstractFileSystem.resolveFile(AbstractFileSystem.java:267)
	- locked <0x22f972e8> (a org.apache.commons.vfs.provider.ftp.FtpFileSystem)
	at org.apache.commons.vfs.provider.AbstractFileObject.getParent(AbstractFileObject.java:512)
	- locked <0x22f972e8> (a org.apache.commons.vfs.provider.ftp.FtpFileSystem)
	at org.apache.commons.vfs.provider.ftp.FtpFileObject.getInfo(FtpFileObject.java:177)
	at org.apache.commons.vfs.provider.ftp.FtpFileObject.refresh(FtpFileObject.java:208)
	at org.apache.commons.vfs.provider.AbstractFileSystem.resolveFile(AbstractFileSystem.java:319)
	- locked <0x22f972e8> (a org.apache.commons.vfs.provider.ftp.FtpFileSystem)
	at org.apache.commons.vfs.provider.AbstractFileSystem.resolveFile(AbstractFileSystem.java:267)
	- locked <0x22f972e8> (a org.apache.commons.vfs.provider.ftp.FtpFileSystem)
	at org.apache.commons.vfs.provider.AbstractFileObject.resolveFile(AbstractFileObject.java:670)
	at at.js.jtransporter.transporter.VFSTransporter.createFile(VFSTransporter.java:118)
	at at.js.jtransporter.worker.resource.ResourceWorker.createFile(ResourceWorker.java:80)
	at at.js.jtransporter.worker.resource.ResourceWorker.processJob(ResourceWorker.java:51)
	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)
"pool-1-thread-4":
	at org.apache.commons.vfs.provider.AbstractFileSystem.resolveFile(AbstractFileSystem.java:267)
	- waiting to lock <0x22f972e8> (a org.apache.commons.vfs.provider.ftp.FtpFileSystem)
	at org.apache.commons.vfs.provider.AbstractFileSystem.getRoot(AbstractFileSystem.java:242)
	at org.apache.commons.vfs.provider.ftp.FtpFileSystem.getClient(FtpFileSystem.java:108)
	- locked <0x22f999e0> (a java.lang.Object)
	at org.apache.commons.vfs.provider.ftp.FtpFileObject.doGetOutputStream(FtpFileObject.java:490)
	at org.apache.commons.vfs.provider.AbstractFileObject.getOutputStream(AbstractFileObject.java:1219)
	at org.apache.commons.vfs.provider.DefaultFileContent.getOutputStream(DefaultFileContent.java:373)
	at at.js.jtransporter.transporter.VFSTransporter.createFile(VFSTransporter.java:119)
	at at.js.jtransporter.worker.resource.ResourceWorker.createFile(ResourceWorker.java:80)
	at at.js.jtransporter.worker.resource.ResourceWorker.processJob(ResourceWorker.java:51)
	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)

Found 1 deadlock.