Just to say - since this first post yesterday, I’ve gone through a lot of stuff, none of it has made any difference.
The Lambda function, once started, stays ‘alive’ between invocations - all global variables are maintained, including the couchbase DB cluster connection, and the resulting bucket and collection references.
Each subsequent invocation uses the existing connection, without having to re-open a new connection.
I’m setting context.callbackWaitsForEmptyEventLoop = false which helps the invocation exit properly.
The error 201 I’m getting from couchbase seems to imply that it’s waiting for something to be concluded, but there are no user defined timeouts that I’m aware of?