I have some code that does some initialization (including making a
Although I believe the API has stated that JTextArea#append(...) is thread safe, I've heard of problems with it and would recommend that this only be called on the EDT. The classic example of this is to use a SwingWorker and append to the JTextArea in the process method by calling publish.
For me, it'll be hard to make any specific suggestions to you though without code. I do have to wonder though if you're putting the EDT to sleep somewhere in your code.
Edit: as per your comment check out this tutorial: Concurrency in Swing
Edit 2: as per comment by Tim Perry, loss of thread safety and the reasoning behind this has been posted in this Java bug and which has to do with this line of code where text is added to the JTextArea's Document:
doc.insertString(doc.getLength(), str, null);
The line decomposes into two lines:
The issue is that a problem can occur if the Document, doc, changes between lines 1 and 2, especially the Document length.