CI gets stuck forever until times out

[sundb]

Description

Recently, Redis CI has also been getting stuck frequently, especially in a slow environment. When I tried to roll back to the version from one year ago, it also got stuck. So it wasn't caused by the recent modifications.
All these tests share a common case: they send a large number of commands.
i tried to write some logs and found that they always get stuck in the middle of sending commands, but Redis itself has no issues.
sundb/redis/actions/runs/15722400756/job/44305647413
redis/redis/actions/runs/15720680684/job/44300809458
redis/redis/actions/runs/15668828605/job/44136574780

When I specified the ubuntu version as 22.04, all these problems disappeared.

Platforms affected

• Azure DevOps
• GitHub Actions - Standard Runners
• GitHub Actions - Larger Runners

Runner images affected

• Ubuntu 22.04
• Ubuntu 24.04
• macOS 13
• macOS 13 Arm64
• macOS 14
• macOS 14 Arm64
• macOS 15
• macOS 15 Arm64
• Windows Server 2019
• Windows Server 2022
• Windows Server 2025

Image version and build link

Image: ubuntu-24.04
Version: 20250609.1.0
Included Software: https://github.com/actions/runner-images/blob/ubuntu24/2025060[9](https://github.com/sundb/redis/actions/runs/15722400756/job/44305647413#step:1:10).1/images/ubuntu/Ubuntu2404-Readme.md
Image Release: https://github.com/actions/runner-images/releases/tag/ubuntu24%2F20250609.1

Is it regression?

no

Expected behavior

ci tests to complete. Not hang.

Actual behavior

CI gets stuck forever until times out

Repro steps

no

[hemanthmanga]

Hi @sundb, Thank you for bringing this issue to our attention. We will look into this issue and will update you after investigating.


[sundb]

@hemanthmanga thanks.

[akilesh-amaran]

Hi @sundb , Could you please re-run your workflow and share me the logs

[sundb]

@akilesh-amaran sure, I'll run one.

[sundb]

hi @akilesh-amaran This is the CI I just ran.
I’ve been investigating the cause of this issue over the past couple of days. I found that the problem gets stuck at Tcl’s write() and flush(). In the failing tests, we write 500,000 commands, but around 300,000, it starts to get stuck. Initially, the delay is about 6 seconds, and as we continue writing more commands, the delay becomes increasingly longer. The stuck happens in a very consistent pattern.
Thanks for your help.

[akilesh-amaran]

Hi @sundb , Could you please update the sync and try with the latest version .

[sundb]

@akilesh-amaran please take a look: https://github.com/redis/redis/actions/runs/16070509266
still stuck, thx.

Could you please update the sync and try with the latest version .

We use ubuntu-latest by default, so is it always the latest?