Hello Milo-dev,
I've just run into a serious issue when using Milo (0.6.11) and reading data from an OPC UA server (built atop of node-opcua).
My Setup:
1. The Milo client is connected to the server via a network cable and reads data via subscription or using periodic read requests.
Here, I also have an OPC UA expert tool on the server side to monitor values in:
CurrentSubscriptionCount
CurrentSessionCount
I see quite reasonable values that match the number of open connections and subscriptions to the server from the Milo client and the OPC UA client tool (say, 2). So far, so good.
2. I physically disconnect the network cable between the Milo client and the OPC UA server. The stats in the OPC UA client tool don't change.
3. After a minute or so (I tried with different time periods of network interruption but didn't see any pattern), I reconnected the cable.
And here, all goes awry:
The OPC UA client tool shows a sudden spike in stats from 2 connections to 5, sometimes 10. The same goes for the number of subscriptions. After a while, the stats go down to expected values.
From our Milo client logs, I see these errors:
2025-01-30 23:18:40.032 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=163 for PublishResponse
2025-01-30 23:18:40.032 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=167 for PublishResponse
2025-01-30 23:18:41.083 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=173 for CreateSessionResponse
2025-01-30 23:18:41.086 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=174 for CreateSessionResponse
2025-01-30 23:18:41.091 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=175 for CreateSessionResponse
2025-01-30 23:18:41.091 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=169 for ReadResponse
2025-01-30 23:18:41.092 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=170 for ReadResponse
2025-01-30 23:18:41.092 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=171 for ReadResponse
2025-01-30 23:18:41.092 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=172 for ReadResponse
2025-01-30 23:18:41.096 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=176 for CreateSessionResponse
2025-01-30 23:18:41.099 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=177 for CreateSessionResponse
2025-01-30 23:18:41.101 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=178 for CreateSessionResponse
2025-01-30 23:18:41.103 WARN 48072 --- [d-thread-pool-4] o.e.m.o.s.c.t.u.UascClientMessageHandler : No pending request with requestId=179 for CreateSessionResponse
Why do I think that the issue may be related to Milo and not just something wrong with the node-opcua server?
Because I tried the same test when I started the second OPC UA expert client tool (on the same machine where I have the Milo client) with an open tab,
where I have the same nodes monitored like my Milo client does.
So I repeated the test with the network cable disconnection and watched the stats on the first OPC UA expert client tool (the same machine where I have the OPC UA server),
and there was no spike in the number of opened sessions.
---
Mikalai
