I develop a utils class that try to connect on each available COM port to find out which one has the stuff i'l interested in plugged onto.
I use the following principle:
for each Com port available:
- connect using some parameters( 8 bit, 1 bit stop no parity and expected baud rate)
- send a specific frame, wait for answer or timeout after xx ms
- disconnect
I use a separate thread to do one port check, thread pool is define as number of available processor minus 1. In my case, there is up to 7 ports check at the "same time".
The JVM crashes.
hs_err_pid9828.log
If i don't use multithread to check port com, from time to time, one is not closed.
Code used is:
` public static List findPortToUse(final Supplier<SerialManager> smGenerator, final Function<CheckPort, Boolean> identificationChecker) {
final BasicThreadFactory factory = new BasicThreadFactory.Builder().namingPattern("findComPortToUse_thread%d").build();
// minus 1 (one left to manage the main thread)
final int nbPara Math.max(Runtime.getRuntime().availableProcessors() -1, 1);
final ExecutorService executorService = Executors.newFixedThreadPool(nbPara, factory);
// ExecutorService's tasks to runs
final Set<Callable<CommPortIdentifier>> callables = new HashSet<>();
// for each serial port found, check it
SerialManager.getAllAvailablePorts().forEach(port -> {
callables.add(new CheckPort<>(port, smGenerator.get(), identificationChecker));
});
final List<CommPortIdentifier> res = new ArrayList<>();
try {
final List<Future<CommPortIdentifier>> futures = executorService.invokeAll(callables);
executorService.shutdown();
executorService.awaitTermination(callables.size() * 2L, TimeUnit.SECONDS);
for (Future<CommPortIdentifier> future : futures) {
if (future.get() != null) {
res.add(future.get());
}
}
} catch (Exception e) {
executorService.shutdownNow();
LOG.error("findPortToUse was interrupted: " + e.getMessage()), e);
}
return res;
}`
CheckPort's call method is defined as follow:
` public final CommPortIdentifier call() throws Exception {
final String portName = port.getName();
LOG.debug("Start checking of " + portName);
if (!sm.connect(port, DataBitsMode.EIGHT, StopBitMode.ONE, ParityMode.NONE, BaudsMode.BAUDS_115200)) {
// connection failed
LOG.debug("Connection failed on " + portName + ", assuming bad port. ");
return null;
}
// connection succeed
LOG.debug("Connection succeed on " + portName + ", checking line identification");
CommPortIdentifier toUse = null;
if (identChecker != null && identChecker.apply(this) == Boolean.TRUE) {
toUse = port;
}
LOG.debug("Disconnection asked on " + portName + ", sending frame");
sm.requestDisconnect();
// wait for disconnection end
try {
Thread.sleep(500);
} catch (Exception e) {
LOG.error("Thread sleep in findPortToUse failed: " + e, e);
}
return toUse;
}`
I develop a utils class that try to connect on each available COM port to find out which one has the stuff i'l interested in plugged onto.
I use the following principle:
for each Com port available:
I use a separate thread to do one port check, thread pool is define as number of available processor minus 1. In my case, there is up to 7 ports check at the "same time".
The JVM crashes.
hs_err_pid9828.log
If i don't use multithread to check port com, from time to time, one is not closed.
Code used is:
` public static List findPortToUse(final Supplier<SerialManager> smGenerator, final Function<CheckPort, Boolean> identificationChecker) {
CheckPort's call method is defined as follow:
` public final CommPortIdentifier call() throws Exception {