Session recycling issue

[egonelbre]

We've been seeing some kind of session recycling issue in our unit tests. I'm not quite sure where exactly the problem lies. It could be a spanner emulator bug, or something in the default spanner library. I was unable to recreate the issue using just spanner library and spanner emulator, so I'm suspecting go-sql-spanner.

The error message is the following:

ExecContext failed: spanner: code = "FailedPrecondition", desc = "Cannot read or query using a transaction after it has been committed or rolledback.", requestID = "1.4e5b33ee11eb3bc7.1.3.246.1"

Or

Previously received a different request with this seqno

I synthesized regression tests using ai here #664.

#626 and #608 could be due to the same reason.

[egonelbre]

Ok, I was able to reproduce this issue only using googleapis/spanner library. It seems that running these tests in parallel is necessary to repro the issue. googleapis/google-cloud-go#13436