golang spanner test library crashes after a while

Question

Spanner GO library crashes after few mins perhaps after this query (although this has been successful earlier) Version cloud.google.com/go/spanner v1.11.0

2021/02/01 00:45:32.564971 spannertest.inmem: Querying: SELECT * FROM tenant_config WHERE commit_time > "2021-02-01T00:44:32Z"

Crashinfo

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x30 pc=0xae3bcb]

goroutine 214 [running]:
cloud.google.com/go/spanner/spannertest.(*server).ExecuteSql(0xc00009b4a0, 0xf74c00, 0xc0001e8270, 0xc0003e8c60, 0xc00009b4a0, 0xc0001e8270, 0xc0008a4ba0)
        /Users/mpathak/Development/gopkgs/pkg/mod/cloud.google.com/go/[email protected]/spannertest/inmem.go:491 +0x3b
google.golang.org/genproto/googleapis/spanner/v1._Spanner_ExecuteSql_Handler(0xd0f8a0, 0xc00009b4a0, 0xf74c00, 0xc0001e8270, 0xc00088b020, 0x0, 0xf74c00, 0xc0001e8270, 0xc0004f4060, 0x14)
        /Users/mpathak/Development/gopkgs/pkg/mod/google.golang.org/[email protected]/googleapis/spanner/v1/spanner.pb.go:3581 +0x217
google.golang.org/grpc.(*Server).processUnaryRPC(0xc0003a1500, 0xf7e800, 0xc00018a900, 0xc00089a000, 0xc0001ac2a0, 0x152c7d8, 0x0, 0x0, 0x0)
        /Users/mpathak/Development/gopkgs/pkg/mod/google.golang.org/[email protected]/server.go:1194 +0x50a
google.golang.org/grpc.(*Server).handleStream(0xc0003a1500, 0xf7e800, 0xc00018a900, 0xc00089a000, 0x0)
        /Users/mpathak/Development/gopkgs/pkg/mod/google.golang.org/[email protected]/server.go:1517 +0xcfd
google.golang.org/grpc.(*Server).serveStreams.func1.2(0xc000606140, 0xc0003a1500, 0xf7e800, 0xc00018a900, 0xc00089a000)
        /Users/mpathak/Development/gopkgs/pkg/mod/google.golang.org/[email protected]/server.go:859 +0xa1
created by google.golang.org/grpc.(*Server).serveStreams.func1
        /Users/mpathak/Development/gopkgs/pkg/mod/google.golang.org/[email protected]/server.go:857 +0x204

Answer 1

This seems to be caused by a bug in the ExecuteSql method implementation of spannertest. The session pool of the Spanner client will execute a ping statement every 50 minutes to keep sessions alive on the backend. These SELECT 1 statements are executed without a transaction, which means that the backend should default to a single-use read-only transaction. The inmem server of spannertest assumes that the client will always specify a TransactionSelector: https://github.com/googleapis/google-cloud-go/blob/c7ecf0f3f454606b124e52d20af2545b2c68646f/spanner/spannertest/inmem.go#L491

I've opened an issue for it here: https://github.com/googleapis/google-cloud-go/issues/3639