zenoh-debug

Minimal reproducible example for pub/sub race condition w/zenoh-0.7.0.

The example program creates to "client" sessions for a Zenoh daemon running as Docker container. sub_client connects and subscribes to a keyexpr, before pub_client also connects and puts a value for this keyexpr. The message never arrives at the subscriber.

As a workaround, wait a set interval between subscribe and publish, which varies depending on the target platform.

Build

git clone https://github.com/alerei/zenoh-debug.git
cd zenoh-debug
mkdir build
cd build
cmake -G Ninja -DCMAKE_BUILD_TYPE=Debug ..
cmake --build .

Run

docker run -d --rm --name zenoh -p 7447:7447 -p 8000:8000 -e RUST_LOG=debug eclipse/zenoh --adminspace-permissions=rw --rest-http-port=8000
./zenoh-debug

Expected behavior

• prints "z_put returned 0"
• prints "lib_subscribe_callback"
• exits with code 0

Actual behavior

• prints "z_put returned 0"
• runs indefinitely

Workaround

Remove comment @main.c:55 (usleep (1000))

Notes

z_declare_subscriber returns with success, so one would expect the subscription to be in place at this point. However, the value published with z_put afterwards never arrives unless a certain amount of time has passed between sub and put.