Java APM


OpenCensus-Java has been integrated with MongoDB’s event listeners to retrieve metrics for executed operations.

The integration can be found at OpenCensus enabled

and used accordingly with

as per

import io.opencensus.apm.EventListener; // The integration to add to your MongoDB Java driver user

MongoClientOptions opts = MongoClientOptions.builder()
                                            .addCommandListener(new EventListener())

MongoClient client = new MongoClient(new ServerAddress(serverAddress), opts);


The metrics that we are collecting include

Metric Search suffix Unit
Bytes read mongo/client/bytes_read By
Bytes written mongo/client/bytes_written By
Roundtrip latency mongo/client/roundtrip_latency ms
Errors mongo/client/errors “1”

as per

Installing it

Assuming that we are using Maven, we can download and install the integration

git clone mongodb-apm-java


Install sample

Assuming you have a MongoDB instance running at localhost:27017 with a created database media-searches and some content with a key called key inside a collection youtube-searches, let’s change directories into the directory that we git-cloned the integration as per Installing it

cd mongodb-apm-java
mvn install

Next our code looks like this

package io.opencensus.apm;

import com.mongodb.BasicDBObjectBuilder;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.MongoClient;
import com.mongodb.MongoClientOptions;
import com.mongodb.ServerAddress;

import io.opencensus.apm.EventListener;


import io.opencensus.exporter.stats.stackdriver.StackdriverStatsConfiguration;
import io.opencensus.exporter.stats.stackdriver.StackdriverStatsExporter;

public class Inspector {
    public static void main(String ...args) {
        try {
        } catch (Exception e) {
            System.err.println("Error while enabling OpenCensus and its exporters: " + e.toString());

        BufferedReader stdin = new BufferedReader(new InputStreamReader(;

        MongoClientOptions opts = MongoClientOptions.builder()
                                    .addCommandListener(new EventListener())

        MongoClient client = new MongoClient(new ServerAddress("localhost"), opts);

        DB db = client.getDB("media-searches");
        DBCollection dc = db.getCollection("youtube_searches");

        while (true) {
            try {
                System.out.print("> ");
                String line = stdin.readLine();
                String processed = line.toUpperCase();

                DBCursor dcc = dc.find(BasicDBObjectBuilder.start("key", line).get());
                while (dcc.hasNext()) {
                    DBObject cur =;
                    System.out.println("< " + cur);

            } catch (IOException e) {
                System.err.println("Exception "+ e);

    private static void enableOpenCensusExporting() throws IOException {
        String gcpProjectId = "census-demos";

        // The stats exporter

stored in file mongodb-apm-java/src/main/java/io/opencensus/apm/

Running sample

For simplicity while writing this tutorial, we used Stackdriver Monitoring in the code sample and then

mvn exec:java -Dexec.mainClass=io.opencensus.apm.Inspector

whose prompt screen should look like this

Viewing metrics

On opening up Stackdriver Monitoring at

and searching for prefix “OpenCensus/mongo/client/”


Resource URL
OpenCensus enabled Java EventListener
MongoDB Event listener JavaDoc