Keeping session alive for custom time using environment (enabling better use of high concurrency)

We now have high concurrency for notebooks in pipeline in public preview. This is great news for us using custom pools (and all using private endpoint and therefor using custom pools).

However for high concurrency to take place we off course need a session to be active. The problem is we cannot choose how long a session is active and they time out very fast.

My suggestion is to let user control the time to keep a session alive after no one using it. An ideal place to make this would be in the environment.