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!!!
