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From "Sebb (JIRA)" <>
Subject [jira] Created: (NET-220) TFTPServer is not threadsafe
Date Mon, 19 May 2008 16:07:58 GMT
TFTPServer is not threadsafe

                 Key: NET-220
             Project: Commons Net
          Issue Type: Bug
    Affects Versions: 2.0
            Reporter: Sebb

The TFTPServer class is not threadsafe.

There are several reasons for this:

Ctors call private launch() method which creates a thread and start()s it.
This publishes the instance before it has been fully constructed.

Various instance fields are not thread-safe - e.g. serverReadDirectory_ is neither final nor
volatile, and accesses to it are not synchronized. 
Although it is only written by the ctors, the lack of synch means that the field may not be
visible to other threads.

As far as possible, instance fields should be made final - this guarantees that the field
will be visible to other threads.

One of the shutdown_ variables is volatile (so is threadsafe) but the shutdown_ variable in
the nested TFTPTransfer class is not,  yet is accessed from multiple threads.

The access to the variable serverException is not synch; should probably be volatile.

Patch to follow.

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