Cause

Document session (Marten.IDocumentSession) is accessed in possibly multithreaded context (Parallel.ForEach, ThreadPool.QueueUserWorkItem capture session).

Reason for rule

Document session is not threadsafe.

How to fix violations

Construct sessions per consuming site.

Examples

Violates

ThreadPool.QueueUserWorkItem(_ => {
    var issues = session.LoadMany<Issue>("Issue-1", "Issue-2");
})

Does not violate

ThreadPool.QueueUserWorkItem(_ => {
    using (var session = store.OpenSession())
    {
        var issues = session.LoadMany<Issue>("Issue-1", "Issue-2");
    }
});