Message delays when network under load

[yuzu-ogura]

Is there an already existing issue for this?

• I have searched the existing issues

Expected behavior

as soon as possible to recovery sending message after occupation network.

Current behavior

During sending message, we maliciously occupied network for 10 seconds, after occupation network, it takes at least 30 seconds to recovery sending message.

Steps to reproduce

1. start a subscriber
2. start a publisher
3. network bandwidth is nearly 10MB/s, message size is 2MB, each message sending will cost 300 ms.
4. after communication successful, use iperf to occupation network, it will cost 10 seconds, the data send will block in the meanwhile
5. after occupation network, it takes at least 30 seconds to recovery sending message.
6. and then message send normally.

Fast DDS version/commit

Fast-RTPS version: 2.6.8

Platform/Architecture

Ubuntu Focal 20.04 amd64

Transport layer

UDPv4

Additional context

Im not sure whether my scene is similar with #1062 ?

XML configuration file

No response

Relevant log output

No response

Network traffic capture

No response

[Javgilavi]

Hi @yuzu-ogura,

Thank you for reporting this issue!

It seems that the problem might be related to an accumulation of messages during periods of high network usage, causing significant delays once the messages can be received again.

There is a data member in the UDP Transport Description that could address this issue. Please try using non_blocking_send.

When the bandwidth is saturated, this option ensures that a sent message is assumed to be lost instead of accumulating during the high-occupancy period.

If this does not resolve the issue, please share the QoS settings you are using in this scenario, and I will follow up to further investigate the problem.