PROSAGA码农传奇-go-并行执行DynamoDB查询（全局二级索引的BatchGetItems）

<div class =“post-text”itemprop =“text”>
  <P>
    根据
    <a href="https://docs.aws.amazon.com/lambda/latest/dg/go-programming-model-handler-types.html" rel="nofollow noreferrer">
      文件
    </A>
    ，全局变量独立于Lambda函数的处理程序代码。这导致缓冲区随着时间的推移而积累。
  </p>
  <P>
    纠正参考贴在下面。
  </p>
   <pre>
    <code>
      package main

import (
    "context"
    "fmt"
    "os"
    "sync"

"github.com/aws/aws-lambda-go/lambda"
    "github.com/aws/aws-sdk-go/aws"
    "github.com/aws/aws-sdk-go/aws/session"
    "github.com/aws/aws-sdk-go/service/dynamodb"
    "github.com/aws/aws-sdk-go/service/dynamodb/dynamodbattribute"
)

func exitWithError(err error) {
    fmt.Fprintln(os.Stderr, err)
    os.Exit(1)
}

//HandleRequest : Lambda entry point
func HandleRequest(ctx context.Context, data LambdaInputJSON) ([]interface{}, error) {
    output := DynamoDBBatchGetRecords(data)
    return output, nil
}

func main() {
    lambda.Start(HandleRequest)
}

func DynamoDBBatchGetRecords(a LambdaInputJSON) []interface{} {
    var dataOut []interface{}
    var wg = &sync.WaitGroup{}
    var mtx = &sync.Mutex{}

iterations := len(a.Ids)
    wg.Add(iterations)
    for i := 0; i < i; i++ {
        go func(i int) {
            defer wg.Done()
            var outputData []interface{}
            sess, err := session.NewSession(&aws.Config{
                Region: aws.String("aws-region"),
            })
            if err != nil {
                exitWithError(fmt.Errorf("failed to make Query API call, %v", err))
            }
            ddb := dynamodb.New(sess)
            queryInput := &dynamodb.QueryInput{
                Limit:            aws.Int64(1),
                TableName:        aws.String("table"),
                IndexName:        aws.String("index"),
                ScanIndexForward: aws.Bool(false),
                ConsistentRead: aws.Bool(false),
                KeyConditions: map[string]*dynamodb.Condition{
                    "index-column": {
                        ComparisonOperator: aws.String("EQ"),
                        AttributeValueList: []*dynamodb.AttributeValue{
                            {
                                S: aws.String(a.Ids[i]),
                            },
                        },
                    },
                },
            }
            output, err := ddb.Query(queryInput)

if err != nil {
                exitWithError(fmt.Errorf("E1 failed to make Query API call, %v", err))
            }
            err = dynamodbattribute.UnmarshalListOfMaps(output.Items, &outputData)
            if err != nil {
                exitWithError(fmt.Errorf("E2 failed to unmarshal Query result items, %v", err))
            }

mtx.Lock()
            dataOut = append(dataOut, outputData[0])
            mtx.Unlock()

}(i)
    }
    wg.Wait()
    return dataOut
}

</code>
  </pre>
</DIV>