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!!!
--
boB Gage
Software Engineer
Merge Healthcare
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