Hi, I locked the SerialConnector connecting methods. Look like discovering serial port concurrently cause some troubles with rxtx.
Say me if the last trunk is fixing your concurrent session opening problems. On the SerialPortUnavailableExceptions, it's triggered by the impossibility to find the port in the list of available port. Do you use some kind of USB/RS232 adapters ? You can run in a "port in use" exception if you try to open the same port two time. Thanks for the feedback, Julien Le Tue, 28 Jul 2009 10:44:29 -0400, boB Gage <[email protected]> a écrit : > Found a work-around for my immediate issue, but it speaks of a much > deeper problem in the Mina and/or rxtx layers. > > I have added a static lock around my chunk of code that calls the > IoConnector.connect() method. I have locked code lazily, so the > critical code includes the bulk of my open() method; this consists of > building the IoConnector, configuring it, calling connect(), and > waiting on the ConnectFuture returned (if not null). It may be > that a much tighter lock is all that is needed -- that is beyond the > scope of my work-around. > > With no two ports attempting an open operation concurrently, the > symptoms (Exceptions and loss of the serial port) have stopped. I > have two tests going on (different pieces of hardware), and both have > passed 12 hours now without showing any problems. > > Apparently that maybe-collision the logs were hinting at was a real > collision (though I misnamed IoSession.open() as the culprit) -- > whether it's Mina or rxtx is beyond my knowledge. But apparently > two threads attempting to open different serial ports at the same > time *can* cause fatal problems. [ It's very timing based; I've > seen runs go 6 hours before failing; seen others fail in under 10 > minutes. ] > > A repeating (ie unrecoverable) SerialPortUnavailableException is the > one consistent symptom. I cannot explain why early tests got a > single PortInUseException first, nor why later tests got a > recoverable SerialPortUnavailableException before complete failure -- > but the RejectedExecutionExceptions were definitely unrelated red > herrings. > > It seems likely this is a serial-specific issue, as I have run many > similar tests using socket connections without seeing this behaviour. > > Thanks again for all the help!! > boB > > PS. Opps, keep forgetting to say: Mina 2.0.0-M6, RxTx 2.1.7 r2 > > > > boB Gage wrote: > > Have made some more progress on this issue. > > The RejectedExecutionException's were my fault and have been > > eliminated. [ Executor handling periodic requests was getting > > shut down and re-started, rather than destroyed and recreated. ] > > > > I still, however, have the case where after some un-constant number > > of successful serial port open/timeout/close cycles I start seeing > > SerialPortUnavailableExceptions. > > > > With my newest code I'm seeing a new pattern (twice in two runs): > > * A number of successful open/timeout/close cycles on the port > > * A single SerialPortUnavailableException > > * Several more successful open/timeout/close cycles on the port > > * A series of SerialPortUnavailableExceptions, one for every > > connection attempt until the program is stopped and restarted. > > > > Two pieces of new behavior here. 1) I've never before seen the > > port go unavailable and come back again (the first single > > exception). 2) I'm no longer seeing a PortInUseException at the > > edge of the port going unavailable. > > > > Some more factoids that may or may not help: > > * With one serial port, this problem is very rare (I've seen runs > > over 24 hours). With each additional serial port, the occurrence > > rate goes up. > > * Logs make it look like the problem *MIGHT* be a collision > > between two IoSession.open() calls happening concurrently > > (different ports, of course). Could there be something non-thread > > safe in Mina's serial layer and/or the rxtx library it's using?? > > * The message text of the SerialPortUnavailableExceptions reads > > "Serial port not found" > > > > Thanks in advance, > > boB Gage > > > > > > > > boB Gage wrote: > >> I'm seeing three different exceptions on the serial ports and am > >> unsure what they exactly mean. > >> > >> Can anyone provide details as to *why* each of these may be throw: > >> * PortInUseException > >> * SerialPortUnavailableException > >> * RejectedExecutionException > >> > >> I have seen each of the preceding exceptions while trying to open > >> a serial port. The first two make the open fail, the third does > >> not (though the open operation has not completely succeeded > >> either -- no data flows on the port.) > >> > >> There are two specific cases that I have seen, both while > >> attempting to connect to a device that's temporarily unavailable > >> (ie powered off): > >> > >> 1) My program opens the port, times out, closes it, waits, and > >> tries again (proper behavior). This cycle continues fine for > >> awhile (time varies) then a single PortInUseException is thrown. > >> On the next, and every following, attempt a > >> SerialPortUnavailableException is thrown. The > >> SerialPortUnavailableException continues until my program is shut > >> down and restarted -- then it immediately can open the port again. > >> > >> 2) Same situation, same timeout cycles, but for some reason a > >> RejectedExecutionException is thrown. The "open" still returns > >> true, but no data flows on the port. Eventually the attempt > >> times out. One the next, and every following, attempt the > >> RejectedExecutionException is thrown and the behavior does not > >> change. > >> > >> In both cases, turning on the far end device after the first > >> exception has no affect. The port, once failed stays that > >> way. Stopping and restarting our program has immediately cleared > >> up the issue each and every time. Unfortunately, stopping & > >> restarting our problem is not a viable solution. > >> > >> I have seen timing changes have some effect. With a 5-second > >> delay between connection attempts only 27 attempts succeeded > >> (timed out) over a period of about 8 minutes before throwing the > >> PortInUseException. Changing that delay to 20 seconds, over 220 > >> attempts were made over a period of 6+ hours before the exception > >> was thrown. > >> > >> Any clues??????? > >> > >> Thanks in advance!!! > >> > > >
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