I have a cluster of rabbitmqs. And configure the spring.rabbitmq.address=xxx,yyy,cccc
Then I start two consumer clients. The question is that the clients only connect one node, there,s not connection to the other nodes. I trace the codes, and found that :
public Connection newConnection(ExecutorService executor, AddressResolver addressResolver, String clientProvidedName) throws IOException, TimeoutException {
if (this.metricsCollector == null) {
this.metricsCollector = new NoOpMetricsCollector();
}
FrameHandlerFactory fhFactory = this.createFrameHandlerFactory();
ConnectionParams params = this.params(executor);
if (clientProvidedName != null) {
Map<String, Object> properties = new
HashMap(params.getClientProperties());
properties.put("connection_name", clientProvidedName);
params.setClientProperties(properties);
}
if (this.isAutomaticRecoveryEnabled()) {
AutorecoveringConnection conn = new AutorecoveringConnection(params,
fhFactory, addressResolver, this.metricsCollector);
conn.init();
return conn;
} else {
List<Address> addrs = addressResolver.getAddresses();
Exception lastException = null;
Iterator var8 = addrs.iterator();
while(var8.hasNext()) {
Address addr = (Address)var8.next();
try {
**FrameHandler handler = fhFactory.create(addr);
AMQConnection conn = this.createConnection(params, handler, this.metricsCollector);
conn.start();
this.metricsCollector.newConnection(conn);
return conn;**
} catch (IOException var12) {
lastException = var12;
} catch (TimeoutException var13) {
lastException = var13;
}
}
if (lastException != null) {
if (lastException instanceof IOException) {
throw (IOException)lastException;
}
if (lastException instanceof TimeoutException) {
throw (TimeoutException)lastException;
}
}
throw new IOException("failed to connect");
}
}
We can see that it creates one connection then returned. But if I wanna the other consumer client can connect to the left nodes instead the same node, although both of the consumer clients have the same configuration:
spring:
rabbitmq:
username: aaaa
password: aaaa
virtual-host: /
addresses: xxxx:5672,yyy:5672,zzzzz:5672
listener:
simple:
concurrency: 4
max-concurrency: 4
prefetch: 4
What should I do ？ can someone give some suggestions?
The RabbitMQ team monitors this mailing list and only sometimes answers questions on StackOverflow.
Try rotating the list of addresses in each client's configuration:
First - xxxx:5672,yyy:5672,zzzzz:5672
Second - yyy:5672,zzzzz:5672,xxxx:5672
Third - zzzzz:5672,xxxx:5672,yyy:5672
Related
I am working on a legacy (Java 6/7) project that uses ProcessBuilder to request a UUID from the machine in an OS-agnostic way. I would like to use the Process.waitFor(long timeout, TimeUnit unit) method from Java 8, but this isn't implemented in Java 6. Instead, I can use waitFor(), which blocks until completion or an error.
I would like to avoid upgrading the version of Java used to 8 if possible as this necessitates a lot of other changes (migrating code away from removed internal APIs and upgrading a production Tomcat server, for example).
How can I best implement the code for executing the process, with a timeout? I was thinking of somehow implementing a schedule that checks if the process is still running and cancelling/destroying it if it is and the timeout has been reached.
My current (Java 8) code looks like this:
/** USE WMIC on Windows */
private static String getSystemProductUUID() {
String uuid = null;
String line;
List<String> cmd = new ArrayList<String>() {{
add("WMIC.exe"); add("csproduct"); add("get"); add("UUID");
}};
BufferedReader br = null;
Process p = null;
SimpleLogger.debug("Attempting to retrieve Windows System UUID through WMIC ...");
try {
ProcessBuilder pb = new ProcessBuilder().directory(getExecDir());
p = pb.command(cmd).start();
if (!p.waitFor(TIMEOUT, SECONDS)) { // No timeout in Java 6
throw new IOException("Timeout reached while waiting for UUID from WMIC!");
}
br = new BufferedReader(new InputStreamReader(p.getInputStream()));
while ((line = br.readLine()) != null) {
if (null != line) {
line = line.replace("\t", "").replace(" ", "");
if (!line.isEmpty() && !line.equalsIgnoreCase("UUID")) {
uuid = line.replace("-", "");
}
}
}
} catch (IOException | InterruptedException ex) {
uuid = null;
SimpleLogger.error(
"Failed to retrieve machine UUID from WMIC!" + SimpleLogger.getPrependedStackTrace(ex)
);
// ex.printStackTrace(System.err);
} finally {
if (null != br) {
try {
br.close();
} catch (IOException ex) {
SimpleLogger.warn(
"Failed to close buffered reader while retrieving machine UUID!"
);
}
if (null != p) {
p.destroy();
}
}
}
return uuid;
}
You can use the following code which only uses features available under Java 6:
public static boolean waitFor(Process p, long t, TimeUnit u) {
ScheduledExecutorService ses = Executors.newSingleThreadScheduledExecutor();
final AtomicReference<Thread> me = new AtomicReference<Thread>(Thread.currentThread());
ScheduledFuture<?> f = ses.schedule(new Runnable() {
#Override public void run() {
Thread t = me.getAndSet(null);
if(t != null) {
t.interrupt();
me.set(t);
}
}
}, t, u);
try {
p.waitFor();
return true;
}
catch(InterruptedException ex) {
return false;
}
finally {
f.cancel(true);
ses.shutdown();
// ensure that the caller doesn't get a spurious interrupt in case of bad timing
while(!me.compareAndSet(Thread.currentThread(), null)) Thread.yield();
Thread.interrupted();
}
}
Note that unlike other solutions you can find somewhere, this will perform the Process.waitFor() call within the caller’s thread, which is what you would expect when looking at the application with a monitoring tool. It also helps the performance for short running sub-processes, as the caller thread will not do much more than the Process.waitFor(), i.e. does not need to wait for the completion of background threads. Instead, what will happen in the background thead, is the interruption of the initiating thread if the timeout elapsed.
I have a Jersey server running locally, it exposes a SSE resource just like the examples here: https://jersey.github.io/documentation/latest/sse.html. I have a local webpack Angular app, that binds to the exposed GET endpoint and listens for data.
On the GET, I start up a thread to send notifications at regular intervals over 6-8 seconds. I don't see anything on the client UNTIL the EventOutput object is closed.
What am I doing wrong, and how can I fix this?
The server code WORKS with just a simple curl, i.e.:
curl http://localhost:8002/api/v1/notify
But on both Chrome and Safari the following code exhibits the behavior
Client (TypeScript):
this.evSource = new EventSource('http://localhost:8002/api/v1/notify');
this.evSource.addEventListener(
'event',
(x => console.log('we have ', x))
);
this.evSource.onmessage = (data => console.log(data));
this.evSource.onopen = (data => console.log(data));
this.evSource.onerror = (data => {
console.log(data);
this.evSource.close();
});
Server (Java):
// cache callback
public void eventCallback(Iterable<CacheEntryEvent<? extends Integer, ? extends Integer>> events) {
for (CacheEntryEvent<? extends Integer, ? extends Integer> x : events) {
LOGGER.info("{} Sending the following value: " + x.getValue(), Thread.currentThread().getId());
final OutboundEvent sseEvent = new OutboundEvent.Builder().name("event")
.data(Integer.class, x.getValue()).build();
this.broadcaster.broadcast(sseEvent);
}
}
#GET
#Produces(SseFeature.SERVER_SENT_EVENTS)
#ApiOperation(value = "Setup SSE pipeline", notes = "Sets up the notification pipeline for clients to access")
#ApiResponses(value = {
#ApiResponse(code = HttpURLConnection.HTTP_UNAUTHORIZED,
message = "Missing, bad or untrusted cookie"),
#ApiResponse(code = HttpURLConnection.HTTP_OK,
message = "Events streamed successfully")
})
#Timed
#ResponseMetered
public EventOutput registerNotificationEvents(
#HeaderParam(SseFeature.LAST_EVENT_ID_HEADER) String lastEventId,
#QueryParam(SseFeature.LAST_EVENT_ID_HEADER) String lastEventIdQuery) {
if (!Strings.isNullOrEmpty(lastEventId) || !Strings.isNullOrEmpty(lastEventIdQuery)) {
LOGGER.info("Found Last-Event-ID header: {}", !Strings.isNullOrEmpty(lastEventId) ? lastEventId : lastEventIdQuery );
}
LOGGER.info("{} Received request", Thread.currentThread().getId());
this.continuation = true;
final EventOutput output = new EventOutput();
broadcaster.add(output);
Random rand = new Random();
IntStream rndStream = IntStream.generate(() -> rand.nextInt(90));
List<Integer> lottery = rndStream.limit(15).boxed().collect(Collectors.toList());
IgniteCache<Integer, Integer> cache = this.ignite.cache(topic_name);
executorService.execute(() -> {
try {
lottery.forEach(value -> {
try {
TimeUnit.MILLISECONDS.sleep(500);
LOGGER.info("{} Sending the following value to Ignite: " + value + " : " + count++, Thread.currentThread().getId());
if (!cache.isClosed()) {
cache.put(1, value);
}
} catch (InterruptedException ex) {
ex.printStackTrace();
}
});
TimeUnit.MILLISECONDS.sleep(500);
continuation = false;
TimeUnit.MILLISECONDS.sleep(500);
if (!output.isClosed()) {
// THIS is where the client sees ALL the data broadcast
// in one shot
output.close();
}
} catch (InterruptedException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
}
});
LOGGER.info("{} Completing request", Thread.currentThread().getId());
return output;
}
}
Looks like http://github.com/dropwizard/dropwizard/issues/1673 captures the problem. GZip default won't flush even if upper levels ask for it. Solution is something like
((AbstractServerFactory)configuration.getServerFactory()).getGzipFilterFactory().setSyncFlush(true);
will enable flushing to synchronize with GZip if disabling GZip all up is not an option
I created MyListener which will start listening (using TcpListener) on his own thread upon creation. the TcpListener should handle multiple clients so i am running inside infinte while and handle each client in special task.
this is my code:
public class MyListener
{
public event EventHandler<MessageEventArgs> MessageReceived;
public MyListener()
{
var thread = new Thread(Listen);
thread.Start();
}
private void Listen()
{
TcpListener server = null;
try
{
server = new TcpListener(IPAddress.Any, 8977);
server.Start();
while (true)
{
var client = server.AcceptTcpClient();
Task.Run(() =>
{
try
{
var msg = GetMessageFromClient(client);
MessageReceived?.Invoke(this, new MessageEventArgs { Message = msg });
}
catch (Exception)
{
}
finally
{
client.Close();
}
});
}
}
catch (Exception)
{
}
finally
{
if (server != null)
server.Stop();
}
}
private string GetMessageFromClient(TcpClient client)
{
var bytes = new byte[client.ReceiveBufferSize];
var stream = client.GetStream();
var i = stream.Read(bytes, 0, bytes.Length);
var message = Encoding.UTF8.GetString(bytes, 0, i);
return message;
}
}
here are my questions:
how can i ensure that the task handle the client will use the client i pass to it when i start the task and not different client (becuase after the task start we return to the AcceptTcpClient method and may get new client)
in my example and with multiple clients handled by the same method ("GetMessageFromClient") do i need to put some kind of locking on this
method?
I succcesfully created SNMP agent using snmp4j libraray
Here is the refrence code.
My query is how can i make this agent to run always to listen all incoming OIDs from manager.??
public synchronized void listen() throws IOException
{
TransportIpAddress address2= new UdpAddress(2069);
AbstractTransportMapping transport;
if (address2 instanceof TcpAddress)
{
transport = new DefaultTcpTransportMapping((TcpAddress) address2);
}
else
{
// transport = new DefaultUdpTransportMapping( (UdpAddress) address2);
transport = new DefaultUdpTransportMapping();
}
ThreadPool threadPool = ThreadPool.create("DispatcherPool", 10);
MessageDispatcher mtDispatcher = new MultiThreadedMessageDispatcher(threadPool, new MessageDispatcherImpl());
// add message processing models
mtDispatcher.addMessageProcessingModel(new MPv1());
mtDispatcher.addMessageProcessingModel(new MPv2c());
// add all security protocols
SecurityProtocols.getInstance().addDefaultProtocols();
SecurityProtocols.getInstance().addPrivacyProtocol(new Priv3DES());
//Create Target
CommunityTarget target = new CommunityTarget();
target.setCommunity( new OctetString("password"));
Snmp snmp = new Snmp(mtDispatcher, transport);
snmp.addCommandResponder(this);
transport.listen();
System.out.println("Listening on " + address);
try
{
this.wait();
}
catch (InterruptedException ex)
{
Thread.currentThread().interrupt();
}
}
In my app I need to download several images from a server. I use this code to get a byte array :
HttpConnection connection = null;
InputStream inputStream = null;
byte[] data = null;
try
{
//connection = (HttpConnection)Connector.open(url);
connection = (HttpConnection)Connector.open(url, Connector.READ_WRITE, true);
int responseCode = connection.getResponseCode();
if(responseCode == HttpConnection.HTTP_OK)
{
inputStream = connection.openInputStream();
data = IOUtilities.streamToBytes(inputStream);
inputStream.close();
}
connection.close();
return data;
}
catch(IOException e)
{
return null;
}
The url are formed with the suffix ";deviceSide=false;ConnectionType=MDS - public" (without spaces) and it is working perfectly well.
The problem is that with phones that do not have a sim card, we can't connect to the internet via the MDS server. So we changed to use the connection factory and let BB choose whatever he wants :
ConnectionFactory connFact = new ConnectionFactory();
ConnectionDescriptor connDesc;
connDesc = connFact.getConnection(url);
if (connDesc != null)
{
final HttpConnection httpConn;
httpConn = (HttpConnection)connDesc.getConnection();
try
{
httpConn.setRequestMethod(HttpConnection.GET);
final int iResponseCode = httpConn.getResponseCode();
if(iResponseCode == HttpConnection.HTTP_OK)
{
InputStream inputStream = null;
try{
inputStream = httpConn.openInputStream();
byte[] data = IOUtilities.streamToBytes(inputStream);
return data;
}
catch(Exception e)
{
e.printStackTrace();
return null;
}
finally{
try
{
inputStream.close();
} catch (IOException e)
{
e.printStackTrace();
return null;
}
}
}
}
catch (IOException e)
{
System.err.println("Caught IOException: " + e.getMessage());
}
}
return null;
The connection works because it select the good prefix (interface=wifi in our case), but this create another problem.
Some images are not well downloaded, some of them (not the sames at each try) are corrupted, but only when the phone use a wifi connection to get these images.
How can I avoid this problem ? What method to get a connection do I have to use ? Is it possible to check if the user have a sim card in orderto use MDS - public ?
Here is an example of a corrupted image :
error image http://nsa30.casimages.com/img/2012/06/28/120628033716123822.png
try this:
public static String buildURL(String url) {
String connParams = "";
if (WLANInfo.getWLANState() == WLANInfo.WLAN_STATE_CONNECTED) {
connParams = ";interface=wifi"; //Connected to a WiFi access point.
} else {
int coverageStatus = CoverageInfo.getCoverageStatus();
//
if ((coverageStatus & CoverageInfo.COVERAGE_BIS_B) == CoverageInfo.COVERAGE_BIS_B) {
connParams = ";deviceside=false;ConnectionType=mds-public";
} else if ((coverageStatus & CoverageInfo.COVERAGE_DIRECT) == CoverageInfo.COVERAGE_DIRECT) {
// Have network coverage and a WAP 2.0 service book record
ServiceRecord record = getWAP2ServiceRecord();
//
if (record != null) {
connParams = ";deviceside=true;ConnectionUID=" + record.getUid();
} else {
connParams = ";deviceside=true";
}
} else if ((coverageStatus & CoverageInfo.COVERAGE_MDS) == CoverageInfo.COVERAGE_MDS) {
// Have an MDS service book and network coverage
connParams = ";deviceside=false";
}
}
Log.d("connection param"+url+connParams);
//
return url+connParams;
}
private static ServiceRecord getWAP2ServiceRecord() {
String cid;
String uid;
ServiceBook sb = ServiceBook.getSB();
ServiceRecord[] records = sb.getRecords();
//
for (int i = records.length -1; i >= 0; i--) {
cid = records[i].getCid().toLowerCase();
uid = records[i].getUid().toLowerCase();
//
if (cid.indexOf("wptcp") != -1
&& records[i].getUid().toLowerCase().indexOf("wap2") !=-1
&& uid.indexOf("wifi") == -1
&& uid.indexOf("mms") == -1) {
return records[i];
}
}
//
return null;
}
What happens when you append interface=wifi? Can you run the network diagnostic tool attached to below kb article and run all tests with SIM removed
http://supportforums.blackberry.com/t5/Java-Development/What-Is-Network-API-alternative-for-legacy-OS/ta-p/614822
Please also note that when download large files over BES/MDS there are limits imposed by MDS. Please ensure you review the below kb article
http://supportforums.blackberry.com/t5/Java-Development/Download-large-files-using-the-BlackBerry-Mobile-Data-System/ta-p/44585
You can check to see if coverage is sufficient for BIS_B (MDS public) but that won't help you if you are trying to support SIM-less users. I wonder if the problem is in an incomparability between the connection on Wi-Fi and IOUtilities.streamToBytes(). Try coding as recommended in the API documents.