Concurrency Issues

[sunshine-attack]

I'm running into concurrency issues using the 2.0.0x implementation. Depending on the the timing of each call to the UserManager, I receive the following error when trying to use more than 1 API call that incorporates the RavenDB session in a controller context:

Only a single concurrent async request is allowed per async client instance.

My understanding is that the RavenDb AsyncDocumentSession only allows one async request at a time per instance of itself. This results in the above error being thrown, again depending on the timing, if more than one request is used per controller context.

Is there a way to avoid this? Do I need to wire up a new ApplicationUserManager with a new AsyncDocumentSession each time I make a API call to ApplicationUserManager?

[tugberkugurlu]

yes, AsyncDocumentSession is not thread safe. You need a new instance of AsyncDocumentSession for each request in a concurrent environment. This is not an AspNet.Identity.RavenDB implementation restriction, it's how RavenDB sessions work.

[sunshine-attack]

Isn't it a AspNet.Identity.RavenDB implementation restriction though? Because if the RavenUserStore accepted a DocumentStore and opened a new session itself on every call instead of accepting a singular session, this problem would go away.

It seems a bit cumbersome to have to instantiate a new ApplicationUserManger multiple times in a single context. It appears contrary to how the default Entity implementation works and prevents AspNet.Identity.RavenDBfrom being a drop-in replacement for the Entity implementation.

[tugberkugurlu]

then you have another problem which is unit of work. RavenDB supports transactions and an identity library shouldn't be responsible creating your session.

[sunshine-attack]

I've never used the transaction feature of RavenDB, but I can appreciate that it is useful to have available. I see the design choice.

Thanks for explaining your design choice.

[tugberkugurlu]

sure, happy to help. Thanks for bringing this up.