What happens when DataWriter::write() returned?

[ruoruoniao]

I found that sometimes since DataWriter::write() returned, DataReader didn't receive published data.
But write() will use a little long time.
What is it waiting for?
What does it mean when it returns?

QoS:
both RELIABLE_RELIABILITY_QOS
both TRANSIENT_LOCAL_DURABILITY_QOS
both max_blocking_time = {10, 0}

[jsan-rt]

Hi @ruoruoniao,

We would need some more information regarding your application Qos configuration to know exactly why it's happening. Since you mentioned you are using RELIABLE_RELIABILITY_QOS, what you are seeing may be caused by reaching the resource limits specified in the ResourceLimitsQosPolicy as explained in this section of the documentation. If this is the case the DataWriter is waiting for resources to become available and, if max_blocking_time is reached, it will return with a TIMEOUT return code.

[ruoruoniao]

Thanks for your reply~
All Qos settings ↓.

Writer is the same as Reader.

So it just means send complete or timeout instead of a listener receipt?