range task failed without accurate info log to debug

[fengou1]

range task code example

	handler := func(ctx context.Context, r tikvstore.KeyRange) (rangetask.TaskStat, error) {
		stats, err := ddl.SendPrepareFlashbackToVersionRPC(ctx, recovery.mgr.GetStorage().(tikv.Storage), resolveTS, startTS, r)
		return stats, err
	}

	runner := rangetask.NewRangeTaskRunner("br-flashback-prepare-runner", recovery.mgr.GetStorage().(tikv.Storage), int(recovery.concurrency), handler)
	// Run prepare flashback on the entire TiKV cluster. Empty keys means the range is unbounded.
	err = runner.RunOnRange(ctx, []byte(""), []byte(""))
	if err != nil {
		log.Error("region flashback prepare get error")
		return errors.Trace(err)
	}

failure information:

2023-01-06 15:54:25 | I0106 07:54:25.581787 9 restore.go:164] [2023/01/06 07:54:25.581 +00:00] [ERROR] [restore.go:51] ["failed to restore data"] [error="PD returned no region"] [errorVerbose="PD returned no region\ngithub.com/tikv/client-go/v2/internal/locate.(*RegionCache).scanRegions\n\t/root/go/pkg/mod/github.com/tikv/client-go/v2@v2.0.3/internal/locate/region_cache.go:1575\ngithub.com/tikv/client-go/v2/internal/locate.(*RegionCache).BatchLoadRegionsWithKeyRange\n\t/root/go/pkg/mod/github.com/tikv/client-go/v2@v2.0.3/internal/locate/region_cache.go:1196\ngithub.com/tikv/client-go/v2/internal/locate.(*RegionCache).BatchLoadRegionsFromKey\n\t/root/go/pkg/mod/github.com/tikv/client-go/v2@v2.0.3/internal/locate/region_cache.go:1221\ngithub.com/tikv/client-go/v2/txnkv/rangetask.(*Runner).RunOnRange\n\t/root/go/pkg/mod/github.com/tikv/client-go/v2@v2.0.3/txnkv/rangetask/range_task.go:191\ngithub.com/pingcap/tidb/br/pkg/restore.(*Recovery).PrepareFlashbackToVersion\n\t/data2/lc/tidb/br/pkg/restore/data.go:319\ngithub.com/pingcap/tidb/br/pkg/restore.RecoverData\n\t/data2/lc/tidb/br/pkg/restore/data.go:60\ngithub.com/pingcap/tidb/br/pkg/task.RunResolveKvData\n\t/data2/lc/tidb/br/pkg/task/restore_data.go:149\nmain.runRestoreCommand\n\t/data2/lc/tidb/br/cmd/br/restore.go:50\nmain.newFullRestoreCommand.func1\n\t/data2/lc/tidb/br/cmd/br/restore.go:143\ngithub.com/spf13/cobra.(*Command).execute\n\t/root/go/pkg/mod/github.com/spf13/cobra@v1.6.1/command.go:916\ngithub.com/spf13/cobra.(*Command).ExecuteC\n\t/root/go/pkg/mod/github.com/spf13/cobra@v1.6.1/command.go:1044\ngithub.com/spf13/cobra.(*Command).Execute\n\t/root/go/pkg/mod/github.com/spf13/cobra@v1.6.1/command.go:968\nmain.main\n\t/data2/lc/tidb/br/cmd/br/main.go:57\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:250\nruntime.goexit\n\t/usr/local/go/src/runtime/asm_amd64.s:1594\ngithub.com/pingcap/errors.AddStack\n\t/root/go/pkg/mod/github.com/pingcap/errors@v0.11.5-0.20220729040631-518f63d66278/errors.go:174\ngithub.com/pingcap/errors.Trace\n\t/root/go/pkg/mod/github.com/pingcap/errors@v0.11.5-0.20220729040631-518f63d66278/juju_adaptor.go:15\ngithub.com/pingcap/tidb/br/pkg/restore.(*Recovery).PrepareFlashbackToVersion\n\t/data2/lc/tidb/br/pkg/restore/data.go:322\ngithub.com/pingcap/tidb/br/pkg/restore.RecoverData\n\t/data2/lc/tidb/br/pkg/restore/data.go:60\ngithub.com/pingcap/tidb/br/pkg/task.RunResolveKvData\n\t/data2/lc/tidb/br/pkg/task/restore_data.go:149\nmain.runRestoreCommand\n\t/data2/lc/tidb/br/cmd/br/restore.go:50\nmain.newFullRestoreCommand.func1\n\t/data2/lc/tidb/br/cmd/br/restore.go:143\ngithub.com/spf13/cobra.(*Command).execute\n\t/root/go/pkg/mod/github.com/spf13/cobra@v1.6.1/command.go:916\ngithub.com/spf13/cobra.(*Command).ExecuteC\n\t/root/go/pkg/mod/github.com/spf13/cobra@v1.6.1/command.go:1044\ngithub.com/spf13/cobra.(*Command).Execute\n\t/root/go/pkg/mod/github.com/spf13/cobra@v1.6.1/command.go:968\nmain.main\n\t/data2/lc/tidb/br/cmd/br/main.go:57\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:250\nruntime.goexit\n\t/usr/local/go/src/runtime/asm_amd64.s:1594"] [stack="main.runRestoreCommand\n\t/data2/lc/tidb/br/cmd/br/restore.go:51\nmain.newFullRestoreCommand.func1\n\t/data2/lc/tidb/br/cmd/br/restore.go:143\ngithub.com/spf13/cobra.(*Command).execute\n\t/root/go/pkg/mod/github.com/spf13/cobra@v1.6.1/command.go:916\ngithub.com/spf13/cobra.(*Command).ExecuteC\n\t/root/go/pkg/mod/github.com/spf13/cobra@v1.6.1/command.go:1044\ngithub.com/spf13/cobra.(*Command).Execute\n\t/root/go/pkg/mod/github.com/spf13/cobra@v1.6.1/command.go:968\nmain.main\n\t/data2/lc/tidb/br/cmd/br/main.go:57\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:250"]

2023-01-06 15:54:25 | I0106 07:54:25.525873 9 restore.go:164] [2023/01/06 07:54:25.525 +00:00] [ERROR] [data.go:321] ["region flashback prepare get error"] [stack="github.com/pingcap/tidb/br/pkg/restore.(*Recovery).PrepareFlashbackToVersion\n\t/data2/lc/tidb/br/pkg/restore/data.go:321\ngithub.com/pingcap/tidb/br/pkg/restore.RecoverData\n\t/data2/lc/tidb/br/pkg/restore/data.go:60\ngithub.com/pingcap/tidb/br/pkg/task.RunResolveKvData\n\t/data2/lc/tidb/br/pkg/task/restore_data.go:149\nmain.runRestoreCommand\n\t/data2/lc/tidb/br/cmd/br/restore.go:50\nmain.newFullRestoreCommand.func1\n\t/data2/lc/tidb/br/cmd/br/restore.go:143\ngithub.com/spf13/cobra.(*Command).execute\n\t/root/go/pkg/mod/github.com/spf13/cobra@v1.6.1/command.go:916\ngithub.com/spf13/cobra.(*Command).ExecuteC\n\t/root/go/pkg/mod/github.com/spf13/cobra@v1.6.1/command.go:1044\ngithub.com/spf13/cobra.(*Command).Execute\n\t/root/go/pkg/mod/github.com/spf13/cobra@v1.6.1/command.go:968\nmain.main\n\t/data2/lc/tidb/br/cmd/br/main.go:57\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:250"]