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Using Batching in Cloud Pub/Sub Java client API.

This example provides guidance on how to use Pub/Sub's Java client API to batch records that are published to a Pub/Sub topic. Using BatchingSettings correctly allows us to better utilize the available resources (cpu, memory, network bandwidth) on the client machine and to improve throughput. In addition to BatchingSettings, this code sample also demonstrates the use of Avro to encode the messages instead of using JSON strings.

In order to demonstrate this process end-to-end, we also provided a simple Dataflow pipeline that reads these Avro messages from a Pub/Sub topic and streams those records into a BigQuery table.

Components

ObjectPublisher - A generic publisher class that can be used to publish any object as a payload to Cloud Pub/Sub. This publisher class provides various configurable parameters for controlling the BatchingSettings for the publishing client.

EmployeePublisher - An implementation of the ObjectPublisher to publish Avro encoded test records to Cloud Pub/Sub. This will generate random test records using the sample Employee Avro Schema.

IngestionMain - A sample Dataflow pipeline to read the Avro encoded test records and stream them into BigQuery.

Requirements

  • Java 8
  • Maven 3
  • Cloud Pub/Sub topic and subscription
    • The Pub/Sub topic will be used by the client to publish messages.
    • The Pub/Sub subscription on the same topic will be used by the Dataflow job to read the messages.
  • BigQuery table to stream records into - The table schema should match the Avro schema of the messages.

Building the Project

Build the entire project using the maven compile command.

mvn clean compile

Running unit tests

Run the unit tests using the maven test command.

mvn clean test

Publishing sample records to Cloud Pub/Sub

Publish sample Employee records using the maven exec command.

mvn compile exec:java \
  -Dexec.mainClass=com.google.cloud.pso.pubsub.EmployeePublisherMain \
  -Dexec.cleanupDaemonThreads=false \
  -Dexec.args=" \
  --topic <output-pubsub-topic> --numberOfMessages <number-of-messages>"

There are several other optional parameters related to batch settings. These parameters can be viewed by passing the help flag.

mvn compile exec:java \
  -Dexec.mainClass=com.google.cloud.pso.pubsub.EmployeePublisherMain \
  -Dexec.cleanupDaemonThreads=false \
  -Dexec.args="--help"

Usage: com.google.cloud.pso.pubsub.EmployeePublisherMain [options]
  * - Required parameters
  Options:
    --bytesThreshold, -b
      Batch threshold bytes.
      Default: 1024
    --delayThreshold, -d
      Delay threshold in milliseconds.
      Default: PT0.5S
    --elementCount, -c
      The number of elements to be batched in each request.
      Default: 500
    --help, -h

    --numberOfMessages, -n
      Number of sample messages to publish to Pub/Sub
      Default: 100000
  * --topic, -t
      The Pub/Sub topic to write messages to

Streaming Cloud Pub/Sub messages into BigQuery using Dataflow

The IngestionMain pipeline provides a simple example of consuming the Avro records that were published into Cloud Pub/Sub and streaming those records into a BigQuery table. This pipeline example can be compiled and executed using the maven exec command.

mvn compile exec:java \
  -Dexec.mainClass=com.google.cloud.pso.pipeline.IngestionMain \
  -Dexec.cleanupDaemonThreads=false \
  -Dexec.args=" \
  --project=<my-gcp-project> \
  --stagingLocation=<my-gcs-staging-bucket> \
  --tempLocation=<my-gcs-temp-bucket> \
  --runner=DataflowRunner \
  --autoscalingAlgorithm=THROUGHPUT_BASED \
  --maxNumWorkers=<max-num-workers> \
  --subscription=<my-input-pubsub-subscription> \
  --tableId=<my-output-bigquery-table>"

Authentication

These examples use the Google client libraries to implicitly determine the credentials used. It is strongly recommended that a Service Account with appropriate permissions be used for accessing the resources in Google Cloud Platform Project.