[NET-145] Deadlock in TelnetInputStream

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.4
• Fix Version/s: 2.0

Environment

Heavy mutlithreaded environment using Jakarta VFS (which uses Commons Net) for ftp file transfers

• Assignee: Unassigned
• Reporter: Norbert Seekircher
• Created: 28/Nov/06 13:40
• Updated: 03/Jan/07 16:16
• Resolved: 20/Dec/06 10:53

Description

"Sometimes" single threads of our application (each thread transfering data from ftp servers) get locked forever. When monitoring our tool with JConsole, I can see that such a thread usually hangs at org.apache.commons.net.telnet.TelnetInputStream, line 339.

This line contains the statement
__queue.wait();

Unfortunately I haven't found a way to reproduce this issue, it just happens about once a day (while running 24 hours and transfering about 50000 files).

As a quick and dirty workaround: What do you think about replacing this line with something like
long startTime = System.currentTimeMillis();
__queue.wait(60000);
if ((System.currentTimeMillis() - startTime) > 55000) {
throw new InterruptedException("Unknown strange and nasty blocker detected");
}

So at least it would not just block the thread.

Issue Links

• relates to: NET-91 commons.net.FTPClient hangs on disconnect or logout