AWT-EventQueue-0 is your event dispatch thread, and it is indeed blocked reading from a serial port via RXTX a socket via hsqldb. You should use SwingWorker, as suggested by @Kumar. Examples may be found here and here. I found it helpful to examine such examples in a profiler for study.
Thread-6 and Thread-7 appear to belong to your application as instances of Threads.ThreadHorloge in posO2. Regarding thread names:
Every thread has a name for identification purposes. More than one thread may have the same name. If a name is not specified when a thread is created, a new name is generated for it.
Note that SwingWorker and Executors typically include the text pool-n, where n is a sequence number.
Addendum: My EDT is in a RUNNABLE state, so from the code I pasted where do you figure out that it's blocked; and where do you find that the reading via RXTX is the blocking cause?
Sorry, my mistake; corrected above. The EDT isn't BLOCKED in the Thread.STATE sense of waiting for a monitor lock; it's blocked in the sense that it's waiting for the database to respond, at least long enough to be seen atop the call stack when you send the -QUIT signal. Neither serial nor network operations should be scheduled on the EDT.
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