Thanks for the idea. I suppose the GC is a possibility to consider and it's easy with one simple line of code to ask the GC to collect the garbage (though it isn't deterministic whether it will comply with this request in a timely fashion.) But the references between my Java variables and the port objects, when severed, are severed immediately. The references between my app being immediately gone, "Device busy" should not occur. But I'll try your idea and see.

My next test will be similar to the simple test I mentioned above but will use two threads: one to open the port and one to close and reopen it, thus mocking up my actual app's logic. If this test shows it impossible for the second thread to do the reopen because of "Device busy," then it becomes clear that in Solaris, only the thread that opens the port can reopen it while that thread's containing app is running, other threads being disallowed.

---------- Post updated 12-13-11 at 10:09 AM ---------- Previous update was 12-12-11 at 10:50 AM ----------

I am able to generate a similar issue (PortInUseException) when running on Windows with certain unit tests. So, although the issue varies with OS, it is not isolated to Solaris. Moreover, I have been using Java Comm's library for serial ports. But now that I have switched to the RXTX library (which implements the same classes and method, so one only needs to change the namespace in one's code), then the problem goes away in Windows. I do not have an RXTX library for Solaris x86 yet, so I cannot report that result yet. Also, if I do not add an event listener to the serial port in my code (with SerialPort.addEventListener()), then I do not get the issue with either Java Comm or RXTX. Therefore, it seems that SerialPort.removeEventListener() does not work in JavaComm's implementation but does work in RXTX. This fellow found the issue, too: Day after day

I'll need to use a compilation of RXTX for my Solaris x86 machine now.

I do not see this as an OS issue per se, though it does vary in severity between Solaris and Windows. If I find that RXTX resolves the issue in Windows but not in Solaris then I will report that.