Hi,
I'm in the middle of righting a highly multi-threaded app which
uses VFS to write output to a configurable list of FTP servers
and local file systems
String url = baseUrl + fname;
OutputStream ftpOut = null;
PrintStream docOut = null;
try {
log.debug("Uploading to '" + url + "'");
FileObject dirObj = VFS.getManager().resolveFile(baseUrl); // <-- Line
80
if (!dirObj.exists()) {
dirObj.createFolder();
}
FileObject fileObj = dirObj.resolveFile(fname); // <-- Line 84
ftpOut = fileObj.getContent().getOutputStream(); // <-- Line 86
docOut = new PrintStream(ftpOut);
docOut.print(content);
log.info("Upload to '" + url + "' completed");
uploaded = true;
} catch(IOException ioe) {
log.warn("Failure uploading to " + url, ioe);
} finally {
IOUtils.closeQuietly(docOut);
}
This has been working nicely for a while, but has just produced the
following deadlock:
Found one Java-level deadlock:
=============================
"Thread-760":
waiting to lock monitor 0xa805d0dc (object 0xad3dd040, a
org.apache.commons.vfs.provider.ftp.FtpFileSystem),
which is held by "Thread-716"
"Thread-716":
waiting to lock monitor 0x084aa954 (object 0xad3dd588, a java.lang.Object),
which is held by "Thread-720"
"Thread-720":
waiting to lock monitor 0xa805d0dc (object 0xad3dd040, a
org.apache.commons.vfs.provider.ftp.FtpFileSystem),
which is held by "Thread-716"
Java stack information for the threads listed above:
===================================================
"Thread-760":
at
org.apache.commons.vfs.provider.AbstractFileSystem.resolveFile(AbstractFileSystem.java:267)
- waiting to lock <0xad3dd040> (a
org.apache.commons.vfs.provider.ftp.FtpFileSystem)
at
org.apache.commons.vfs.provider.AbstractOriginatingFileProvider.findFile(AbstractOriginatingFileProvider.java:88)
at
org.apache.commons.vfs.provider.AbstractOriginatingFileProvider.findFile(AbstractOriginatingFileProvider.java:62)
at
org.apache.commons.vfs.impl.DefaultFileSystemManager.resolveFile(DefaultFileSystemManager.java:641)
at
org.apache.commons.vfs.impl.DefaultFileSystemManager.resolveFile(DefaultFileSystemManager.java:602)
at
org.apache.commons.vfs.impl.DefaultFileSystemManager.resolveFile(DefaultFileSystemManager.java:570)
at
com.reuters.agency.tvdams.lisa.DocumentOutputCommand.internalExecute(DocumentOutputCommand.java:80)
at
lisa.server.core.command.type.LisaMessageCommand.internalExecute(LisaMessageCommand.java:108)
at
lisa.server.core.command.type.BaseLisaCommand.execute(BaseLisaCommand.java:139)
at
lisa.server.core.command.type.BaseLisaCommand.call(BaseLisaCommand.java:106)
at EDU.oswego.cs.dl.util.concurrent.FutureResult$1.run(Unknown Source)
at EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Worker.run(Unknown
Source)
at java.lang.Thread.run(Unknown Source)
"Thread-716":
at
org.apache.commons.vfs.provider.ftp.FtpFileSystem.getClient(FtpFileSystem.java:106)
- waiting to lock <0xad3dd588> (a java.lang.Object)
at
org.apache.commons.vfs.provider.ftp.FtpFileObject.doGetChildren(FtpFileObject.java:120)
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 <0xad3dd040> (a
org.apache.commons.vfs.provider.ftp.FtpFileSystem)
at
org.apache.commons.vfs.provider.AbstractFileSystem.resolveFile(AbstractFileSystem.java:267)
- locked <0xad3dd040> (a
org.apache.commons.vfs.provider.ftp.FtpFileSystem)
at
org.apache.commons.vfs.provider.AbstractFileObject.resolveFile(AbstractFileObject.java:670)
at
com.reuters.agency.tvdams.lisa.DocumentOutputCommand.internalExecute(DocumentOutputCommand.java:84)
at
lisa.server.core.command.type.LisaMessageCommand.internalExecute(LisaMessageCommand.java:108)
at
lisa.server.core.command.type.BaseLisaCommand.execute(BaseLisaCommand.java:139)
at
lisa.server.core.command.type.BaseLisaCommand.call(BaseLisaCommand.java:106)
at EDU.oswego.cs.dl.util.concurrent.FutureResult$1.run(Unknown Source)
at EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Worker.run(Unknown
Source)
at java.lang.Thread.run(Unknown Source)
"Thread-720":
at
org.apache.commons.vfs.provider.AbstractFileSystem.resolveFile(AbstractFileSystem.java:267)
- waiting to lock <0xad3dd040> (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 <0xad3dd588> (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
org.apache.commons.vfs.provider.DefaultFileContent.getOutputStream(DefaultFileContent.java:356)
at
com.reuters.agency.tvdams.lisa.DocumentOutputCommand.internalExecute(DocumentOutputCommand.java:86)
at
lisa.server.core.command.type.LisaMessageCommand.internalExecute(LisaMessageCommand.java:108)
at
lisa.server.core.command.type.BaseLisaCommand.execute(BaseLisaCommand.java:139)
at
lisa.server.core.command.type.BaseLisaCommand.call(BaseLisaCommand.java:106)
at EDU.oswego.cs.dl.util.concurrent.FutureResult$1.run(Unknown Source)
at EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Worker.run(Unknown
Source)
at java.lang.Thread.run(Unknown Source)
This looks like a nasty bug to me but it's quite possible I'm doing something
stupid. Any ideas?
Richard
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