Throughput of subsequent streams keep decreasing.

[iamPerfPro]

When the http3_client.py is run with 10 requests like this
python3 examples/http3_client.py --ca-certs tests/pycacert.pem
https://localhost:4433/10000000
https://localhost:4433/10000000
https://localhost:4433/10000000
https://localhost:4433/10000000
https://localhost:4433/10000000
https://localhost:4433/10000000
https://localhost:4433/10000000
https://localhost:4433/10000000
https://localhost:4433/10000000
https://localhost:4433/10000000

The output of the above on the client side shows the throughput of each HTTP GET request which I assume is throughput of each stream and it keeps decreasing.

2021-11-21 13:27:27,487 INFO quic [2898d19e5bb23543] ALPN negotiated protocol h3
2021-11-21 13:27:27,487 INFO client New session ticket received
INFO client Response received for GET /10000000 : 10000000 bytes in 0.8 s (96.349 Mbps)
2021-11-21 13:27:29,062 INFO client Response received for GET /10000000 : 10000000 bytes in 1.6 s (50.903 Mbps)
2021-11-21 13:27:29,787 INFO client Response received for GET /10000000 : 10000000 bytes in 2.3 s (34.845 Mbps)
2021-11-21 13:27:30,493 INFO client Response received for GET /10000000 : 10000000 bytes in 3.0 s (26.648 Mbps)
2021-11-21 13:27:31,202 INFO client Response received for GET /10000000 : 10000000 bytes in 3.7 s (21.558 Mbps)
2021-11-21 13:27:31,891 INFO client Response received for GET /10000000 : 10000000 bytes in 4.4 s (18.186 Mbps)
2021-11-21 13:27:32,584 INFO client Response received for GET /10000000 : 10000000 bytes in 5.1 s (15.709 Mbps)
2021-11-21 13:27:33,257 INFO client Response received for GET /10000000 : 10000000 bytes in 5.8 s (13.876 Mbps)
2021-11-21 13:27:33,924 INFO client Response received for GET /10000000 : 10000000 bytes in 6.4 s (12.437 Mbps)
2021-11-21 13:27:34,593 INFO client Response received for GET /10000000 : 10000000 bytes in 7.1 s (11.266 Mbps)
2021-11-21 13:27:34,595 INFO quic [2898d19e5bb23543] Connection close sent (code 0x0, reason )

Why does the throughput decrease for every new stream generated ? The throughput decreased from 96.349 to 11.266.

Does this signify that the streams are not running in parallel.

Please advise on this. Thanks.

[jlaine]

My assumption would be that as you pile on new requests there are more and more requests sharing the bandwidth, so their individual speed drops. You could re-run a test where you run the requests consecutively and see if the behaviour changes.

[github-actions]

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