Merge pull request #12 from halprin/stream-scan-request

Stream Scan Request

Author: halprin

dynamo/delete.go

@@ -11,7 +11,7 @@ import (
 var maxItemsPerBatchRequest = 25
 var tableKeys []*dynamodb.KeySchemaElement
 
-func deleteItems(dynamoItems []map[string]*dynamodb.AttributeValue, tableName string) error {
+func deleteItems(dynamoItems []map[string]*dynamodb.AttributeValue, tableName string, goroutinePool *parallel.Pool) error {
 
 	var err error
 	tableKeys, err = getTableKeys(tableName)
@@ -22,15 +22,6 @@ func deleteItems(dynamoItems []map[string]*dynamodb.AttributeValue, tableName st
 
 	dynamoItemsChunks := chunkItems(dynamoItems)
 
-	concurrency, err := determineConcurrency(tableName)
-	if err != nil {
-		log.Println("Unable determine the concurrency")
-		return err
-	}
-
-	goroutinePool := parallel.NewPool(concurrency, len(dynamoItemsChunks))
-	defer goroutinePool.Release()
-
 	var errorChannels []chan error
 
 	for _, currentItemsChunk := range dynamoItemsChunks {

dynamo/dynamo.go

@@ -5,6 +5,7 @@ import (
 	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/dynamodb"
 	"github.com/halprin/delete-dynamodb-items/config"
+	"github.com/halprin/delete-dynamodb-items/parallel"
 	"log"
 )
 
@@ -25,13 +26,24 @@ func DeleteAllItemsInTable() error {
 
 	tableName := *config.GetTableName()
 
-	items, err := getItems(tableName)
+	concurrency, err := determineConcurrency(tableName)
 	if err != nil {
+		log.Println("Unable determine the concurrency")
 		return err
 	}
 
-	err = deleteItems(items, tableName)
-	return err
+	// 1024 * 1024 / 25 = 41,943.04 ~= 41,944
+	goroutinePool := parallel.NewPool(concurrency, 41944)
+	defer goroutinePool.Release()
+
+	for subItemList := range getItemsGoroutine(tableName) {
+		err = deleteItems(subItemList, tableName, goroutinePool)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
 }
 
 func describeTable(tableName string) (*dynamodb.DescribeTableOutput, error) {

dynamo/scan.go

@@ -6,34 +6,35 @@ import (
 	"log"
 )
 
-func getItems(tableName string) ([]map[string]*dynamodb.AttributeValue, error) {
+func getItemsGoroutine(tableName string) chan []map[string]*dynamodb.AttributeValue {
+	yield := make(chan []map[string]*dynamodb.AttributeValue)
 
-	var scannedItems []map[string]*dynamodb.AttributeValue
-
-	scanInput := &dynamodb.ScanInput{
-		TableName: aws.String(tableName),
-	}
+	go func() {
+		scanInput := &dynamodb.ScanInput{
+			TableName: aws.String(tableName),
+		}
 
-	for {
-		log.Println("Scanning items")
+		for {
+			log.Println("Scanning items")
 
-		scanOutput, err := dynamoService.Scan(scanInput)
-		if err != nil {
-			log.Println("Failed to scan the items")
-			return nil, err
-		}
+			scanOutput, err := dynamoService.Scan(scanInput)
+			if err != nil {
+				log.Println("Failed to scan the items")
+				break
+			}
 
-		scannedItems = append(scannedItems, scanOutput.Items...)
+			yield <- scanOutput.Items
 
-		if scanOutput.LastEvaluatedKey != nil && len(scanOutput.LastEvaluatedKey) > 0 {
-			//there are still items to scan, the the key to start scanning from again
-			scanInput.ExclusiveStartKey = scanOutput.LastEvaluatedKey
-		} else {
-			//no more items to scan, break out
-			break
+			if scanOutput.LastEvaluatedKey != nil && len(scanOutput.LastEvaluatedKey) > 0 {
+				//there are still items to scan, the the key to start scanning from again
+				scanInput.ExclusiveStartKey = scanOutput.LastEvaluatedKey
+			} else {
+				//no more items to scan, break out
+				break
+			}
 		}
-	}
+		close(yield)
+	}()
 
-	return scannedItems, nil
+	return yield
 }
-

generate_mass_data.sh

@@ -9,9 +9,10 @@ aws dynamodb create-table --table-name "${table_name}" --attribute-definitions A
 items_preamble="{\"${table_name}\": ["
 items_middle=""
 items_ending=']}'
+lorem_ipsum='Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec a efficitur nunc. Morbi fermentum sem metus, vel venenatis leo porttitor quis. Etiam maximus neque a pharetra viverra. Sed turpis lacus, blandit ac tortor elementum, scelerisque feugiat risus. Nam malesuada augue et purus aliquet, et semper dolor cursus. Suspendisse volutpat dolor nec efficitur rutrum. Aliquam leo libero, posuere eget vulputate in, luctus nec nibh. Donec eu tellus eu libero scelerisque molestie. Ut sed pretium nibh. Donec suscipit eget dui quis lacinia. Aliquam non pulvinar massa, nec blandit lectus. Cras sollicitudin rhoncus ex. Nunc ipsum dui, dictum in risus nec, convallis rutrum justo. In tempor dui nisl, in fringilla massa vehicula ac. Donec a ipsum luctus, venenatis magna ut, venenatis risus. Vivamus eu dapibus odio. Aenean dapibus urna orci, sed pharetra nunc dapibus ac. Praesent ornare, felis sit amet mattis faucibus, odio arcu laoreet arcu, eu blandit nisi turpis cursus enim.'
 
 for ((index = 1 ; index <= num_items ; index++)); do
-    current_request="{\"PutRequest\": {\"Item\": {\"id\": {\"S\": \"$(uuidgen)\"}}}}"
+    current_request="{\"PutRequest\": {\"Item\": {\"id\": {\"S\": \"$(uuidgen)\"}, \"text\": {\"S\": \"${lorem_ipsum}\"}}}}"
     items_middle="${items_middle}${current_request},"
     if [[ $((index % 25)) == 0 ]]; then
         items_middle=${items_middle::${#items_middle}-1}

parallel/pool.go

@@ -10,7 +10,7 @@ type Pool struct {
 	waitGroup sync.WaitGroup
 }
 
-//poolSize needs to be bigger than taskQueueSize
+//taskQueueSize needs to be bigger than poolSize if you want to saturate the pool
 func NewPool(poolSize int, taskQueueSize int) *Pool {
 	newPool := &Pool{
 		ingestionPoolChannel: make(chan func(), taskQueueSize),