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helloworld standalone example memory leak

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Hi all,

I am using 6.7.1 community version to do some tests, I modified the helloworld standalone example under "\examples\dcps\helloworld\cpp", the program will send 300 samples(or called message?) of 300 topics in a second, and  each sample(or called message?) is about 1k byte. After running about 1 hour, the memory usage of the applications(both of sacpp_helloworld_pub.exe and sacpp_helloworld_sub.exe) are more than 1GB, while at the beginning, they were about 6MB. Does anyone know what's the problem? Do I need to do some configurations to avoid the memory leak?

I just use the default ospl.xml as the OSPL_URI value, the content as show below:


        <Description>Stand-alone 'single-process' deployment and standard DDSI networking.</Description>
        <Service name="ddsi2">
        <Service name="cmsoap">
            <Policy obtain="*.*"/>
    <DDSI2Service name="ddsi2">
            <!-- see the release notes and/or the OpenSplice configurator on DDSI interoperability -->
            <!-- the following one is necessary only for TwinOaks CoreDX DDS compatibility -->
            <!-- <ExplicitlyPublishQosSetToDefault>true</ExplicitlyPublishQosSetToDefault> -->
    <TunerService name="cmsoap">

Sorry for my poor English, and thank you for your great help.


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It might help if you could share the modified code. What might have happened is that you're creating as many instances (i.e. key-values) as you're creating samples and then perhaps don't unregister() or take() the samples .. in which case the administration-overhead related to any 'instance' might explain your observation.




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Hi hans,

Thank you for your suggestions. The code I modified is simple, I just make the publisher and subscriber can be always running, and the MAX_NUM is 300. 

How can I unregister() or take() the samples  to reduce the memory usage? BTW, the topic QOS of the example is set RELIABLE_RELIABILITY_QOS and TRANSIENT_DURABILITY_QOS, and I comment out the TRANSIENT_DURABILITY_QOS.


while (true)
      msgInstance.userID = index++;
      msgInstance.timestamp = getCurrentTime();
      for (int i = 0; i < MAX_NUM; i++)
          status = HelloWorldWriter->write(msgInstance, DDS::HANDLE_NIL);
          checkStatus(status, "MsgDataWriter::write");
      /*cout << "=== [Publisher] writing a message containing :" << endl;
      cout << "    userID  : " << msgInstance.userID << endl;
      cout << "    Message : \"" << msgInstance.message << "\"" << endl;*/




  while (!closed && count < 1500) // We dont want the example to run indefinitely
      for (int i = 0; i < MAX_NUM; i++)
          status = HelloWorldReader->take(msgList, infoSeq, LENGTH_UNLIMITED,
          checkStatus(status, "msgDataReader::take");
          for (DDS::ULong j = 0; j < msgList.length(); j++)
              /*cout << "=== [Subscriber] message received :" << endl;
              cout << "    userID  : " << msgList[j].userID << endl;
              cout << "    Message : \"" << msgList[j].message << "\"" << endl;*/
              outfile << "topic" << i << " " << msgList[j].userID << " " << msgList[j].message << /* " " << msgList[j].timestamp << " " << getCurrentTime() << " " << msgList[j].buf <<*/ endl;
              //closed = true;
          status = HelloWorldReader->return_loan(msgList, infoSeq);
          checkStatus(status, "MsgDataReader::return_loan");


module Simulator{

    typedef char array1024[1024];

    struct Message {
        long msgId;
        array1024 msg;
#pragma keylist Message msgId


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Yeah, I remember that the msgId is a 'key' in the topic so you're creating as many instances as you have key-values.

You could try unregistering the instance after you've written it.


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Hi Payne,

To complement Hans' suggestion, you could modify your code in the following ways:

  1. On the Publishing side, follow your write instruction immediately by a corresponding unregister instruction. This instructs the Writer to release all resources allocated to accomodate for future updates to that instance. Not doing this is what causes your memory leak.
    status = HelloWorldWriter->write(msgInstance, DDS::HANDLE_NIL);
    status = HelloWorldWriter->unregister_instance(msgInstance, DDS::HANDLE_NIL);


  2. Instruct the Writer to automatically unregister after each Write instruction by setting the (OpenSplice specific) autounregister_instance_delay to 0 on the DataWriterLifecycleQosPolicy in your WriterQos.
        DDS::DataWriterQos wQos;
        result = publisher->get_default_datawriter_qos(wQos);
        result = publisher->copy_from_topic_qos(wQos, tQos);
        wQos.writer_data_lifecycle.autodispose_unregistered_instances = false;
        wQos.writer_data_lifecycle.autounregister_instance_delay = DDS::DURATION_ZERO;
        writer = publisher->create_datawriter(topic, wQos, NULL, DDS::STATUS_MASK_NONE);



Erik Hendriks.

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