Finally figured it out.
Doesn’t seem to work in my case, unfortunately.
Can anyone explain what is a shard ???
ETS tables holding process ↔ topic pairs (subscriptions) are “partitioned” into several (# pool size) shards (they seem to also have an associated “garbage collector” ets table each) to distribute load. When a new process is registerd for a topic (if you call “subscribe”), this subscription is saved in a shard according to its :erlang.phash2(pid, pool_size) which is not necesseraly 0, so if you always use 0 for the shard id, you might miss some existing subscriptions.
