lightning: add timeout for "write" RPC

br/pkg/lightning/backend/local/region_job.go

@@ -218,6 +218,10 @@ func (local *Backend) doWrite(ctx context.Context, j *regionJob) error {
 		failpoint.Return(err)
 	})
 
+	var cancel context.CancelFunc
+	ctx, cancel = context.WithTimeoutCause(ctx, 15*time.Minute, common.ErrWriteTooSlow)
+	defer cancel()
+
 	apiVersion := local.tikvCodec.GetAPIVersion()
 	clientFactory := local.importClientFactory
 	kvBatchSize := local.KVWriteBatchSize

br/pkg/lightning/common/retry.go

@@ -90,13 +90,19 @@ var retryableErrorIDs = map[errors.ErrorID]struct{}{
 	drivererr.ErrUnknown.ID():           {},
 }
 
+// ErrWriteTooSlow is used to get rid of the gRPC blocking issue.
+// there are some strange blocking issues of gRPC like
+// https://github.com/pingcap/tidb/issues/48352
+// https://github.com/pingcap/tidb/issues/46321 and I don't know why 😭
+var ErrWriteTooSlow = errors.New("write too slow, maybe gRPC is blocked forever")
+
 func isSingleRetryableError(err error) bool {
 	err = errors.Cause(err)
 
 	switch err {
 	case nil, context.Canceled, context.DeadlineExceeded, io.EOF, sql.ErrNoRows:
 		return false
-	case mysql.ErrInvalidConn, driver.ErrBadConn:
+	case mysql.ErrInvalidConn, driver.ErrBadConn, ErrWriteTooSlow:
 		return true
 	}
 

br/pkg/lightning/common/retry_test.go

@@ -35,6 +35,7 @@ import (
 func TestIsRetryableError(t *testing.T) {
 	require.False(t, IsRetryableError(context.Canceled))
 	require.False(t, IsRetryableError(context.DeadlineExceeded))
+	require.True(t, IsRetryableError(ErrWriteTooSlow))
 	require.False(t, IsRetryableError(io.EOF))
 	require.False(t, IsRetryableError(&net.AddrError{}))
 	require.False(t, IsRetryableError(&net.DNSError{}))