Python SDK hangs without viewer

[rrad5409]

Overview

When using the Python SDK, will block if it is unable to flush the GRPC sink, which completely hangs the library. Starting up a viewer immediately unblocks it. This also blocks the process from exiting (not sure why).

To Reproduce

1. set up a GRPC sink

2. log data

3. call sys.exit()

4. entire process hangs until a viewer connects, then it exits

5. initialise rerun

6. call rr.connect() without a viewer

7. call sys.exit() in another thread

8. entire process hangs until a viewer connects, then it exits

Screen Recording

2026-02-07T21-19-11.mp4

Versions

OS: Pop!_OS 25.04
SDK: 0.27 - 0.29
CLI: rerun-cli 0.29.0 (base lance map_view nasm native_viewer oss_server perf_telemetry re_server release_full release_no_web_viewer web_viewer) [rustc 1.90.0 (1159e78c4 2025-09-14), LLVM 20.1.8] x86_64-unknown-linux-gnu prepare-release-0.29.0 7877197, built 2026-01-30T08:50:57.053553047Z Video features: av1 ffmpeg nas

Related

• RecordingStream with a pending connection hangs forever #9909
• Fire-and-forget logging mode #6933