why can the isolation tester handle only one waiting process?

I had the idea that it would be useful to have some regression tests
that verify that the deadlock checker works as advertised, because we
currently have just about zero test coverage for it. And it's easy
enough to write a regression test that causes a simple 2-way deadlock.
But you can't test anything more interesting than that, because of
this limitation described in the README:

> Currently, at most one step can be waiting at a time. As long as one
> step is waiting, subsequent steps are run to completion synchronously.

Is there any reason not to try to lift that restriction? (And do we
think it's hard?)

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company