Missing rpc-reply from netopeer2-server on callback error with multiple subscribers

[Krisscut]

This issue only occurs after upgrade from

netopeer2-2.2.35 sysrepo-3.3.10 libnetconf2-3.5.5 libyang-3.7.8

to

netopeer2-2.4.1 sysrepo-3.6.11 libnetconf2-3.7.1 libyang-3.12.2

In our case, we have 2 services which have callbacks registered on the same path. One service (orusw/ in c) also have some kind of backdoor mecanism to allow us to simulate a callback failure. The other one (UserManagement / in python) store user information received in the edit config.

An automated test running netopeer2-cli first enable the backdoor mecanism to make the orusw service's callback return an error using an RPC. Then it attempts to perform an edit config. --> ORUSW returns KO, UserManagement processing is fine.

The issue is that sometimes, the netopeer2-cli never receives a rpc-reply from netopeer2-server.

I attached the trace of working / failing case, with client in verb3 mode we cna see that the client doesn't receive a reply.

In failing case I don't see these logs on server side

2025-06-12 13:23:11.073 INFO/UE_APP-OAM/netopeer2-server(PID:3375): [INF]: NP: Generated new event (post edit-config). 2025-06-12 13:23:11.073 INFO/UE_APP-OAM/netopeer2-server(PID:3375): [INF]: NP: Session 23: thread 0 event new RPC. 2025-06-12 13:23:11.073 INFO/UE_APP-OAM/netopeer2-server(PID:3375): [INF]: NP: Session 23: thread 0 event reply error.

client_side_traces_ko.txt client_side_traces_ok.txt server_side_traces_ko.txt server_side_traces_ok.txt