AcceptMessageSession takes from 5 ms to more than few minutes without Timeout exception

[rybczak]

Actual Behavior

1. AcceptMessageSession takes from 5ms to more than 2 minutes - timeout was set to 10ms, 30ms and to default one.

Expected Behavior

We're trying to read messages from Servicebus in Azure environment. Our process is run inside Durable Functions framework and it sometimes fails with FunctionTimeoutException.

We find out that there is a problem with AcceptMessageSession.
Our workflow:

• receive all messages for specific session
• save data into database
• complete all messages from session at once and go to other session

From time to time AcceptMessageSession takes a lot of time (in minutes): in last process run there were 3 AcceptMessageSession invocation which takes from 1 to 3 minutes and 17 invocations which takes less than 10 ms.

We thought that Servicebus will throw exception when methods is taking more than expected.

Versions

• OS platform and version: Azure, azurefunctions: 2.0.12408.0
• .NET Version: .NET Core 2.1
• NuGet package version or commit ID: Microsoft.Azure.ServiceBus 3.4.0