JTextArea append method doesn't always append

I have an application with many custom loggers, and a number of JTextArea
instances for displaying the log entries written to the loggers. Each
JTextArea has a thread associated with it that continuously pulls entries
out of a particular logger and appends that text to the JTextArea. Thus,
each entry written to a logger should show up in the associated JTextArea.

The problem I have is that not all the log entries show up in the text area,
and what shows up and what does not can change with each execution. I've
put print statements before and after the log statements, and before and
after the text area append, and all the expected log entries show up at all
those places. Only in the JTextArea is there variability in what shows up.
Is this a bug in JTextArea, or is this some known behavior?

Lee Graba