I am using the Javamail API connecting to my IMAP server. Everything is working great with the javax.mail.Folder.idle() method. My listener gets called when a new mail comes in. However the problem is idle blocks forever, how do I interrupt it? How do I actually stop the listening without killing my Java program?
I've tried calling Thread.interrupt() on the idle'd thread. Nothing happens. I am running out of ideas.
Performing any operation on that folder (from another thread) will cause idle() method to return immediately. So if you want to forcefully interrupt it, just call close() from a new thread.
If you read the documentation properly, and read the source code, you'll realise that you have to create a new thread for calling .idle().
Allocate that thread to a variable, and whenever you want call the interrupt() on that thread, or just ignore notifications!
If you need to get idle() going again, just rerun the thread!
I created something similar, so you might wanna check it out.
https://github.com/mofirouz/JavaPushMail/blob/master/src/main/java/com/mofirouz/javapushmail/JavaPushMailAccount.java
Good luck
A proper way to abort IDLE command is the following snippet. Note that the Folder instance should be the same as the one used to start idling. I've tested the other solutions proposed on this thread but they didn't work in my case.
IMAPFolder folder = store.getFolder("INBOX");
try {
folder.doOptionalCommand("Abort IDLE error mesage", new IMAPFolder.ProtocolCommand() {
#Override
public Object doCommand(IMAPProtocol p) throws ProtocolException {
p.idleAbort();
return Boolean.TRUE;
}
});
} catch (MessagingException e) {
e.printStackTrace();
}
Related
I have some method with render() name which includes very difficult logic and I call it so in my code
Future<File> fileFuture = null;
try {
fileFuture = executor.getThreadPoolExecutor()
.submit(() -> render());
return fileFuture.get(10,TimeUnit.SECONDS);
} catch (TimeoutException e) {
fileFuture.cancel(true);
throw new MyTimeOutException(e);
}
}
render() method opens some I/O resources and when job doesn't finish
till timeout I get such error when timeout happens
java.nio.channels.ClosedByInterruptException
I investigated this problem and found that this happens because
I/O resources stay still open and Thread cannot be terminated
till these resources won't be closed.
But isn't any way for avoiding this exception
I just need to stop my async method when timeout happens.
and I also want add that I use Spring boot if there is any solution with
Spring please tell me
This exception ClosedByInterruptException will be thrown when a thread performing a blocking read or write on an InterruptibleChannel, like a FileChannel, it's interrupted.
When you call fileFuture.cancel(true) the boolean flag indicates that if the task is blocked, the thread may be interrupted. So, as the thread is blocked in a read or write operation it throws a ClosedByInterruptException.
If you want to get rid of the ClosedByInterruptException, then you render() method to tackle with ClosedByInterruptException, to end the process gracefully if it's thrown.
So if I have a socket server, I can accept each socket and pass it to a executory
while(true){
Socket conn = socketServ.accept();
Runnable task = new Runnable() {
#Override
public void run() {
try{
server.executor(conn);
} catch(IOException e){
}
}
};
exec1.execute(task);
}
Doing this allows my server to run on my threads and does not block the same thread. Because I also have reference to that socket... called "conn" I can successfully return messages as well.
Now I have an RMI interface, which basically lets me call methods back and forth.
for example if I had this method:
public MusicServerResponseImpl CreatePlayerlist(String Name, UserObjectImpl uo) throws RemoteException {
MusicServerResponseImpl res = new MusicServerResponseImpl();
return res;
}
Which returns a serializable object. My concern is when this message gets called, I think it is going to get called in the main thread of the server, and thus will block that thread and slow down parallelism.
What I think is the solution is to have every single RMI method also create a task for an executor.. to speed up the execution of everything...this issue I am seeing however is unlike the socket where I have an object to send information back to, I am unsure how I would return a response from the RMI method, without somehow having to block the thread.
Does that make sense? Basically I am asking how I can execute in parallel with RMI methods while still being able to return results!
Thanks for the help!
Does that make sense?
No. Concurrent calls are natively supported.
See this documentation page and look for the property named maxConnectionThreads.
You could also have tested your assumptions by, for example, printing the current thread name in your server code, and trying to execute concurrent calls and see what happens.
I am working on an application that needs to launch a process and wait for its output. Sometimes the process crashes (very often,) but is not really an issue since I have mitigation tasks. The problem is that Windows detects the process crashed and prompts for user input, to either check for a solution online, or just close the program.
I tried to solve this by waiting for the process to complete in a Runnable submitted to an ExecutorService and using the Future returned to specify a timeout. Speed is not really a concern for the application, and the external process is supposed to run for just a couple of seconds.
This is the code I am using:
final Process process = ...
final ExecutorService service = Executors.newSingleThreadExecutor();
try {
final Future<?> future = service.submit(new Runnable() {
#Override
public void run() {
try {
process.waitFor();
} catch (InterruptedException e) { /* error handling */}
}
});
future.get(10, TimeUnit.SECONDS);
} catch (final TimeoutException e) {
// The process may have crashed
process.destroy();
} catch (final Exception e) {
// error handling
} finally {
service.shutdown();
}
The code above worked well, but the crash dialog still pops up and it doesn't go away without user interaction.
This question presents a similar problem but from a .Net perspective and
proposes to suppress the pop up through the Windows registry, which I cannot do, given that its effect is global to all process in the machine.
Is there a way to prevent the dialog from being displayed at all?
or
Is there a way to detect the application crash and handle it directly
from Java without needing user interaction?
Additional details:
I don't have the source of the external process.
The external process is a console based application (i.e. no GUI.)
Preferably I'm looking for a pure Java based solution (no JNI.)
Thank you.
As already suggested you should use SetErrorMode win32 call. It won't change for the whole system but only for your process and it's children (which is what you want apparently).
The correct call seems to be :
SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOGPFAULTERRORBOX);
See also the MSDN documentation :
http://msdn.microsoft.com/en-us/library/windows/desktop/ms680621%28v=vs.85%29.aspx
Regards.
I am trying to execute external jar from java app.
What is the most elegant way to check if the process has been started successfully and running?
ExtApp.jar is long-term running process, so I can not use Process.waiFor() because it would block my app. I have come up with following code, with idea behind is that the exitValue() throws IllegalThreadStateException if the process has not been yet terminated.
boolean success = false;
try {
Process process = Runtime.getRuntime().exec("java -jar ExtApp.jar");
try {
if (process.exitValue() == 0)
success = true;
} catch (IllegalThreadStateException e) {
success = true;
}
} catch (Exception e) {}
System.out.println(success);
But it is kind of ugly solution. Any ideas for a better one?
There seems to be no elegant solution to the problem. E.g. I ran your code on my PC and got "success" though there is no ExtApp.jar on it. That is, from the point of view of Runtime.exec the process (java.exe) started successfully, no matter what happens afterwards.
The above seems very dubious. You're going to spawn off your process and then test it immediately. The process itself may not have determined whether it's running ok or not (e.g. when does it actually check that jar file eixsts/is loadable/is valid ?)
I think you're better off spawning the process via a new thread, calling/blocking in that thread via Process.waitFor() and then notifying the parent thread (via whatever means - state variable, wait()/notify(), a java.util.concurrent.Future etc.) once the process has exited and you've collected the exit status.
Apache Commons Exec is a useful library for doing this sort of work, including asynchronous spawning/notification of process exit. See the DefaultExecuteResultHandler for more info.
I am trying to spawn a thread for just 1 method. Im getting an IllegalStateException (see below). What this method does it accept a Connection to a database and the database name, and it will generate XML from it. (That part works I am just trying to make it go faster with a new thread because I have multiple XML files to create.
Thread table = new Thread(new Runnable() {
public void run() {
try {
System.out.println("starting");
tableXml(tableConn, dbName);
System.out.println("ending");
}
catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
table.start();
Exception:
java.lang.IllegalStateException: Current state = RESET, new state = FLUSHED
at java.nio.charset.CharsetEncoder.throwIllegalStateException(CharsetEncoder.java:951)
at java.nio.charset.CharsetEncoder.flush(CharsetEncoder.java:640)
at java.nio.charset.CharsetEncoder.encode(CharsetEncoder.java:769)
at com.informix.lang.JavaToIfxType.doConversion(JavaToIfxType.java:841)
at com.informix.lang.JavaToIfxType.JavaToIfxChar(JavaToIfxType.java:145)
at com.informix.jdbc.IfxVarChar.toString(IfxVarChar.java:247)
at com.informix.jdbc.IfxResultSet.getString(IfxResultSet.java:742)
at com.informix.jdbc.IfxResultSet.getString(IfxResultSet.java:785)
at org.apache.commons.dbcp.DelegatingResultSet.getString(DelegatingResultSet.java:225)
at com.test.ex.ExportTask$1.run(ExportTask.java:151)
at java.lang.Thread.run(Thread.java:662)
The line of code that is causing the exception is a resultSet.executeQuery();
So the question is: what am I doing wrong?
Thanks for your help, let me know if you need information
It seems that the problem is because your code is not thread safe. Try giving each new thread that is spawned its own connection instead of sharing a reference of a single connection between all threads in your application.
The exception itself has nothing to do with the way you're firing up a new thread. You're "start-thread-call-method" code is just fine.
The exception is CharsetEncoder related. If I were you, I would google for something like IllegalStateException CharsetEncoder and possibly thread safety.
It is important however, that Whatever classes / framework you're using concurrently are thread safe.
Are you sure the main thread doesn't reset/close the connection while the spawned thread tries using it?
If you're in a Java EE environment (or similar, like Spring), the connection is often linked to the current transaction, which is itself linked to the current thread. So when the transaction ends, the connection is given back to the pool of available connections, but your spawned thread is still trying to use it.