out of order delivery of samples

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out of order delivery of samples

Hi,

We are getting data samples out-of-order on the subscriber side, when we use a QoS profile that is an extension of BuiltInQosLib-  Generic.StrictReliable.HighThroughput or when using a profile that is an extension of Generic.AutoTuning. (I have attached the xml QoS file we are using) 

This occurs even when batching is disabled. 

On the other hand, if we use the default QoS settings then we get samples in order. 

Can you please suggest why this behavior is occuring? 

 

thank you,

shweta 

 

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sumant's picture
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Can you send me a simple reproducer? 

sumant's picture
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They may not be delivered in order, because the Presentation QoS policy (at the DDS::Publisher, DDS::Subscriber) controls how samples are actually presented to the user. Make sure they set access_scope to TOPIC_PRESENTATION and ordered_access to true (http://community.rti.com/rti-oc/510/ndds.5.1.0/doc/html/api_cpp/structDDS__PresentationQosPolicy.html). 

For example, 

<qos_profile>
<subscriber_qos>
<presentation>
<access_scope>TOPIC_PRESENTATION_QOS</access_scope>
<coherent_access>false</coherent_access>
<ordered_access>true</ordered_access>
</presentation>
</subscriber_qos>
</qos_profile>

Similarly for the publisher.

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Last seen: 9 months 1 week ago
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great! thanks it works correctly now.