On 06/11/2014 06:05 PM, Janczuk, Tomasz wrote:
Process level isolation is more costly than sub-process level isolation primarily due to larger memory consumption. For example, CGI has worse cost characteristics than FastCGI when scaled out. But the example closer to Marconi¹s use case is database systems: I can¹t put my finger on a single one that would isolate queries executed by its users using processes.
That is certainly a good point. However not all database systems would entirely isolate users from each other. In some a user could overload the system with lots of slow queries and impact the responsiveness of the database to other users. In extreme cases you could cause deadlocks in the database.
Sub-process multi-tenancy is a not an easy problem, but it is not one that cannot be solved, especially in the context of a messaging system. A messaging system exposes a set of operations that is very well defined and constrained. The cost of these operations can be relatively easily assessed a priori and managed accordingly to provide a secure multi-tenant platform.
I agree it can be done. Not sure whether I agree that its relatively easy to do so - but then it is all relative! :-)
Thanks for the responses though, they have been helpful in improving my understanding.
--Gordon. _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
