Java binding for ZeroMQ

Hi,

is there a stable version of this? Can you tag them respectively to zeroMQ versions? I mean if last stable version is 2.0.10 where can I find the java classes for that?

I see you are using 2.1.0-SNAPSHOT in the sources already?

thanx in advance

I'm finally getting around to upgrading to jzmq-3.1.0 from 2.2.2, and have hit a snag in behavior of Poller. I think it has to do with commit e598f93, where the run_poll() method was changed to raise an error on return codes less than 0. For example:

...
Poller poller = new Poller(1);
poller.register(socket, Poller.POLLIN);
while (!Thread.currentThread().isInterrupted()) {
  if (poller.poll() < 0)
    break;
  ...
}

Previously, this would cleanly exit the loop. Now, it throws an error and kills the thread.

In a high level language binding like jzmq, I would expect the previous behavior instead of the new behavior. It seems like there should be no reason for every call to recv() or poll() to require try/catch. I can understand the call to recv() requiring it, but poll()?

Is there a reason the behavior of throwing a ZMQException is better than detecting error codes and exiting cleanly? Can anyone suggest a superior idiom for cleanly exiting event loops? While I haven't tried ZLoop, I noticed that ZMQQueue and ZMQForwarder do use try/catch around the entire loop. However, ZLoop and ZDispatcher appear not to and may be broken, and I can't find anywhere in ZMsg and ZFrame where it is being done for you. This doesn't seem to be a compatibility issue with libzmq, though I admittedly know very little about the czmq language binding, so perhaps it is for compatibility with that library...?

If someone can weigh in on the desired improvement that can be made (perhaps adding try/catch to ZFrame, etc.?), I would be happy to make the changes and open a pull request.

I had a thought while reviewing the source that the java.nio.ByteBuffer enhancements to Java 1.4 might be a better fit for the send/recv calls (or perhaps some variation on them).

Given that ByteBuffer lets you directly use native heap you can avoid the need to memcpy messages to/from the managed heap.

I know from the documentation that 0MQ is very focused on performance, so this enhancement could possibly boost the performance of the Java bindings (faster send/recv, use less managed heap, fewer GCs) and get them a bit closer to native performance.

Right now the jzmq.dll fails to load when using embedded libraries, unless you modify the ZeroMQ Visual Studio Project to change libzmq.dll to a static library and link jzmq.dll with the static library.

Currently the embedded library logic does not add libzmq.dlll to the JAR. Nor does it attempt to unpack libzmq.dll before attempting to load jzmq.dll which fails because of the libzmq.dll dependency.

Is it possible to create tags for the current version? In the spec file there is currently version 2.1.0. Would be nice if there was also a tag for that version.

Would make our rpm building process a bit easier.

When I try to make in my system, I get the following error:

Making all in src
javac -d . org/zeromq/ZMQ.java org/zeromq/ZMQException.java org/zeromq/ZMQQueue.java org/zeromq/ZMQForwarder.java org/zeromq/ZMQStreamer.java org/zeromq/ZContext.java org/zeromq/ZFrame.java org/zeromq/ZMsg.java org/zeromq/ZThread.java org/zeromq/ZLoop.java org/zeromq/ZDispatcher.java org/zeromq/EmbeddedLibraryTools.java
org/zeromq/ZMQ.java:187: error: unmappable character for encoding ASCII
     * Starts the built-in ??MQ proxy in the current application thread. The proxy connects a frontend socket to a
                           ^
org/zeromq/ZMQ.java:187: error: unmappable character for encoding ASCII
     * Starts the built-in ??MQ proxy in the current application thread. The proxy connects a frontend socket to a
                            ^
2 errors
make[1]: *** [zmq.jar] Error 1
make: *** [all-recursive] Error 1

The encoding of the .java files seems to be utf-8, and when I manually run javac on th efiles with the option -encoding UTF-8, the files compile just fine.

I'm not that experienced with Java so I'm not sure what the actual error is, but I guess encoding autodetection differs from platform to platform.

I also tried to figure out how to patch the Makefile to do this but I couldn't figure it out, so I apologize for not posting a patch with this issue.

First I just want to thank you for the work of java binding of zmq, an amazing product!

I am using zeromq-2.1.4 and jzmq snapshot of 04/17/2011 on Mac OSX. I am trying to use a thread pool to receive message. However, I have difficulties to shut the thread pool down and it always hangs when I call context.term(). I have code attached.

I have read the doc regarding how to close the context cleanly, and I did close the connection before context.term(). But it doesn't seem to work for me.

Question 1: when connect.close is called, what happens to the thread running connection.recv(0)? should it break first? Ideally, I see recv() throw error and unblock the thread is much easier to handle. Also, the doc said the recv will be able to get the signal and unblock itself. but it doesn't seem to work for java binding???

Question 2: should each context be create for each thread (threadlocal)? I tried, and doesn't seem to work all the time, the behavior is rather unpredictable, i.e. most time either error out as mentioned below or hang, but 1 out of ten actually succeed).

Question 3: The doc does mention it is bug that context.term will hange (http://zguide.zeromq.org/page:all#Making-a-Clean-Exit) but it kind alludes there is a workaround. Is this going to be fixed? Can context.term just unblock blocking calls of the socket and close all the connections underlying, so we don't have a chicken or egg problem here (e.g. recv(0) will block unless context.term() is called, but context.term() will block unless connection.close is called, and what happen to the recv(0)?).

---- code -----

Here is a simplified test I wrote: public class TestWorker {

private static final int BLOCK_FLAG = 0;
ZMQ.Socket socket;
ZMQ.Context context;
@BeforeMethod
public void beforeMethod() {
    context = ZMQ.context(1);
    socket = context.socket(ZMQ.PULL);
    socket.connect("tcp://localhost:5557");
}

@Test
public void threadPoolTest() throws InterruptedException {
    ExecutorService executorService = Executors.newFixedThreadPool(3);
    final AtomicBoolean isRunning = new AtomicBoolean(true);
    //submit running task
    for (int i = 0; i < 3; i++) {
        executorService.submit(new Callable<Void>() {
            public Void call() throws Exception {
                 while (isRunning.get()) {
                     byte[] data = socket.recv(BLOCK_FLAG); //block
                     System.out.println(new String(data));
                 }
                return null;   //thread is stopped.
            }
        });
    }
    Thread.sleep(5000L);//let's sleep for 5 sec so that everything is initialized.
    isRunning.set(false);//trying to stop the thread pool.
    socket.close();
    context.term();//NOTE: this never get unblocked. Or sometime just throw errors.
    executorService.shutdown(); //never reach here.
}

} The program usually hangs at term.

--- If error occur, they are like the following, and then program exist. ad file descriptor nbytes != -1 (mailbox.cpp:242) Bad file descriptor nbytes != -1 (mailbox.cpp:242) Bad file descriptor nbytes != -1 (mailbox.cpp:242)

I've tried repeatedly installing jzmq on Mac OS X. Whatever I do, I hit a brick wall with this exception: java.lang.UnsatisfiedLinkError: no jzmq in java.library.path

I have successfully installed (pkg-config and) libzmq and libjzmq into /usr/local/lib from today's github master branches. For jzmq, I did: ./autogen.sh && ./configure --with-zeromq=/usr/local/lib && make && sudo make install But setting java.library.path in any way, even manually at the start of my Java code, or even setting LD_LIBRARY_PATH, has no effect at all - I keep getting that UnsatisfiedLinkError.

I would very much like to use jzmq for my projects, as I already have done a client and server implementation in Python and want to connect it to the Java world. (For the curious: http://gentlefn.github.com/gentle-tp-da92/)

Versions:

• libzmq and jzmq: current github master
• Mac OS X: 10.6.6, up-to-date
• Java (most recent JDK provided by Apple): 1.6.0_22-b04-307-10M3261

I am currently working on ZMTP3.0 CurveZMQ mechanism using jzmq libraries.so,i am having doubt that can i use jzmq-3.1.0 jar which is in maven central to build that security mechanism in my application like using ZAP for Ldap authentication kind of things. or i need any new jar (like next release jars for that )

JZMQ from GitHub (10.22.2013) (x64) ZeroMQ 3.2.4 (x64) (compiled with Visual Studio 2013 and 2012) Windows 8 (x64)

Hello.

I am experiencing a strange behavior of JZMQ. In Windows when ZMQ is trying read data in "recv" and host or port doesn't exist after some timeout (10-30sec) it closes without any exceptions or errors.

If write equivalent code on C++ and libzmq. This bug not exist. It looks like the problem is in jzmq

Example of code:

import org.zeromq.ZContext;
import org.zeromq.ZMQ;

public class MyMainApp {

    public static void main(String[] args) {

        ZContext ctx = new ZContext();
        ZMQ.Socket s = ctx.createSocket(ZMQ.PULL);

        s.connect("tcp://172.16.255.5:55566");

        while(true) {
            String msg = new String( s.recv(0) );
            System.out.print( msg );
        }
    }
}

In pom.xml, the version has changed from -SNAPSHOT to 1.0.0, but development on master has continued.

This breaks dependency management, where versions are expected to be stable (and builds idempotent).

It would probably be a good idea to start publishing built artifacts to a maven repo, either to one of the large public ones or a local one here on github (using pages works fine).

we encountered a problem:

client of c++ binds to server of scala using jzmq, and the client also binds to another server of c++.

when the client is restarted, it connect to servers normally, but server of scala can not receive any msg, otherwise server of c++ is normal to receive msgs.

codes of scala are as following

val context = new ZContext

val in: ZMQ.Socket = {
     val skt = context.createSocket(0) //pair
     skt.bind(inConf.getOrElse("ipc:///data/soft/ai-access/access-server"))
     skt 
}
threadPool.submit {
        new Runnable {
            override def run(): Unit = {
                try {
                    while (!Thread.currentThread.isInterrupted) {
                        val reply = in.recv(0)
                        // ....
                    }
                } catch {
                    case ex: Exception =>
                }
            }
        }
    }

hi, I am reading your project, why do you use ZeroMQ in your project instead of other message queues like Kafka, RabbitMQ... can you tell me about your purpose, the cons and pros of ZeroMQ, thank you so much

We are using zmq inproc socket to transmit messages between threads. we have set Hwm accordingly and using multipart message, i.e send() method with the necessary flag. We are seeing this behavior of large memory consumption when large amount of messages are being transmitted using this socket, the usage is outsize heap. I looked into the page-fault graph and can see that most of the page-fault is created by java_org_zeromq_SocketSend , I tried to trace native allocation using jemalloc and the output obtained also suggest large allocation during SocketSend. From jemalloc output I can see that leak might be associated with zmq msg_t initsize() function. I have attached graph of what I have described above. I tried to use ZMsg.send() along with destroy flag set , but no change in the memory usage pattern. Can someone help me how to tackle the issue.

T E S T S

Running org.zeromq.ZConfigTest Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.031 sec - in org.zeromq.ZConfigTest Running org.zeromq.ZCertStoreTest Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 2.023 sec - in org.zeromq.ZCertStoreTest Running org.zeromq.ZMsgTest Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.009 sec - in org.zeromq.ZMsgTest Running org.zeromq.ZDispatcherTest performanceTest message sent:1,000,000 Tests run: 4, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.836 sec <<< FAILURE! - in org.zeromq.ZDispatcherTest dispatcherPerformanceTest(org.zeromq.ZDispatcherTest) Time elapsed: 0.826 sec <<< ERROR! java.lang.ArithmeticException: / by zero at org.zeromq.ZDispatcherTest.dispatcherPerformanceTest(ZDispatcherTest.java:226)

Running org.zeromq.ZContextTest Tests run: 5, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec - in org.zeromq.ZContextTest Running org.zeromq.ZFrameTest Tests run: 6, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec - in org.zeromq.ZFrameTest Running org.zeromq.ZAuthTest Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 3.424 sec - in org.zeromq.ZAuthTest Running org.zeromq.ZThreadTest Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec - in org.zeromq.ZThreadTest Running org.zeromq.ZLoopTest Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.056 sec - in org.zeromq.ZLoopTest

Results :

Tests in error: ZDispatcherTest.dispatcherPerformanceTest:226 Arithmetic / by zero

Tests run: 38, Failures: 0, Errors: 1, Skipped: 0

[INFO] ------------------------------------------------------------------------ [INFO] Reactor Summary for jzmq-parent 3.1.1-SNAPSHOT: [INFO] [INFO] jzmq-parent ........................................ SUCCESS [ 0.136 s] [INFO] jzmq-jni ........................................... SUCCESS [ 10.970 s] [INFO] jzmq-core .......................................... FAILURE [ 7.094 s] [INFO] jzmq-devices ....................................... SKIPPED [INFO] jzmq ............................................... SKIPPED [INFO] ------------------------------------------------------------------------ [INFO] BUILD FAILURE [INFO] ------------------------------------------------------------------------ [INFO] Total time: 18.262 s [INFO] Finished at: 2021-12-30T20:43:49+08:00 [INFO] ------------------------------------------------------------------------ [ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.16:test (default-test) on project jzmq-core: There are test failures. [ERROR] [ERROR] Please refer to /Users/yuzhao/jzmq/jzmq-core/target/surefire-reports for the individual test results. [ERROR] -> [Help 1] [ERROR] [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch. [ERROR] Re-run Maven using the -X switch to enable full debug logging. [ERROR] [ERROR] For more information about the errors and possible solutions, please read the following articles: [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException [ERROR] [ERROR] After correcting the problems, you can resume the build with the command [ERROR] mvn -rf :jzmq-core

$ java -version
openjdk version "1.8.0_312" OpenJDK Runtime Environment (Zulu 8.58.0.13-CA-macos-aarch64) (build 1.8.0_312-b07) OpenJDK 64-Bit Server VM (Zulu 8.58.0.13-CA-macos-aarch64) (build 25.312-b07, mixed mode)

$uname -a
Darwin MyMacBook-Pro.local 21.1.0 Darwin Kernel Version 21.1.0: Wed Oct 13 17:33:01 PDT 2021; root:xnu-8019.41.5~1/RELEASE_ARM64_T6000 arm64

I am trying to build an Android application that uses jzmq to communicate using norm. Is there any support for Android? My initial solution was to build a .aar with all the compiled libraries, but I wanted to check with the devs for an approved method to build on Android. Would it be possible to have a install readme produced as well?

Folks,

Is the JZMQ licensed under GPL, as the view license link at the top-right of the top-level page shows, or LGPL as it describes in at the bottom of the page? The COPYING and COPYING.LESSER don't seem to clarify things.

I'm hopeful that you'll respond LGPL, so that we can use JZMQ.

Thanks, Sean