Are DynamoDB API operations async?

[mazzy89]

I’m running the API operation BatchWriteItem inside a for-loop where I read a JSON file line-by-line. The table has the Write Throughput Unit set to 3.

// data is a variable filled by reading a JSON file

scanner := scanner.NewScanner(data)
for scanner.Scan() {
  data = scanner.Bytes()

  // Unmarshal the data to Golang struct

  // convert the data to a DynamoDB item

  log.Println(“Making a request…”)
 
  // where bwi is a BatchWriteInput struct
  if _, err := client.BatchWriteItem(context.TODO, &bwi); err != nil {
    return fmt.Errorf(err)
  }
}

The problem with such code snippet is that it fails to upload even when the batch has two only items. The error I get is that it exceeds the maximum throughput.

The most interesting part is the output I get:

Making a request…
Making a request…
Making a request…
Making a request…
Making a request…
Making a request…
Making a request…
ProvisionedThroughputExceededException

The following output for a blocking method does not have much sense. I would have expected to block waiting for the BatchWriteItem request to return.

My only guess is that API operations are async but I couldn’t find any evidence in the code.

For the sake of completeness, I might add that the size of each item read from the JSON file is about ~6KB.