libiperf hanging with tests over 100s

[Shaun-3adesign]

Context

when using libiperf to run a test the test never returns if the duration 100 seconds, traffic is generated but results are never returned.

• Version of iperf3: 3.1.3, 3.9, 3.14 and 3.16

• Operating system (and distribution, if any): ubuntu 20.04 and 22.04

Bug Report

using libiperf to run a test greater than 100s causes it to hang after sending data, running iperf3 from a command line works fine

• Expected Behavior expect the call to run_client_test to return the json output

• Actual Behavior the call never returns

• Steps to Reproduce run a tcp test with a duration over 100s and json enabled

• Debugging digging into this it actually get stuck doing the following file: iperf/src/iperf_api.c function: iperf_json_finish line: 4885 fprintf(test->outfile, "%s\n", test->json_output_string);

it just never returns, but I was able to print out test->json_output_string to a file before calling it also if I set the log file before running the test it completes without issue

python wrapper where initial issue was seen https://github.com/thiezn/iperf3-python/issues/53

[bmah888]

Couple questions:

1. What happens if you don't enable JSON output and just get the default human-readable output?
2. What's the network like between the client and the server? In particular, any chance there's some kind of stateful firewall in between?

[Shaun-3adesign]

Hi Bruce,

If you don’t enabler JSON output it returns as normal

The connection is across the internet not sure what firewall they have that side but I have a fritzbox.

I can write out the same data before calling the fprintf line by creating a file and writing to it. It just seems to hang outputting to stdout as if I set a logfile it works fine.

I’ve have now tested much more and it always works if I set a logfile. Currently got a 5 hour test g oing

I am using python not sure if that would make a difference

Regards

Shaun

From: Bruce A. Mah @.> Date: Friday, 9 February 2024 at 18:53 To: esnet/iperf @.> Cc: shaun hirst @.>, Author @.> Subject: Re: [esnet/iperf] libiperf hanging with tests over 100s (Issue #1648)

Couple questions:

1. What happens if you don't enable JSON output and just get the default human-readable output?
2. What's the network like between the client and the server? In particular, any chance there's some kind of stateful firewall in between?

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