Reporting client-side metrics

The Cloud Bigtable HBase client for Java can collect client-side metrics that enable you to monitor Cloud Bigtable's performance. Other Cloud Bigtable client libraries do not provide client-side metrics. This page explains how to enable client-side metrics in the HBase client for Java and lists the metrics that are available.

Enabling metrics

Cloud Bigtable's HBase client for Java uses Dropwizard Metrics to collect and report client-side metrics. Because collecting metrics can add a very small amount of latency (single-digit microseconds) to each request, metrics are not enabled by default. The following sections explain how to enable client-side metrics.

Using the Log4j reporter

The simplest way to enable metrics is to add the following line to your Log4j configuration file:

log4j.category.com.google.cloud.bigtable.metrics=DEBUG

This configuration setting turns on metrics collection and logs Cloud Bigtable metrics with an SLF4J logger.

Using other reporters

You can use other types of reporters by updating your application's code. For example, here is a reporter that sends metrics to a Graphite server:

Graphite pickledGraphite = new PickledGraphite(new InetSocketAddress("graphite.example.com", 2004));
DropwizardMetricRegistry registry = new DropwizardMetricRegistry();
GraphiteReporter reporter =
    GraphiteReporter.forRegistry(registry.getRegistry())
        .convertRatesTo(TimeUnit.SECONDS)
        .convertDurationsTo(TimeUnit.MILLISECONDS)
        .filter(MetricFilter.ALL)
        .build(pickledGraphite);
reporter.start(1, TimeUnit.MINUTES);
BigtableClientMetrics.setMetricRegistry(registry);

Dropwizard Metrics provides reporters for JMX, console logging, SLF4J, and CSV. There are also a variety of third-party reporters available.

Available metrics

This section describes the metrics that are available when client-side metrics are enabled. Each metric has one of the following types:

• Counter: A cumulative count per Java virtual machine (JVM).
• Meter: Count information plus throughput information (a count per the last minute, 5 minutes, or 15 minutes)
• Timer: Meter information plus latency information (such as median, mean, and 95th percentile)

Only certain metrics are collected for each type of request. See "Example: Metrics for a Put request" for an example of the metrics that are collected during a Put request.

Channel-level metrics

Type	Name	Description
Counter	google-cloud-bigtable.sessions.active	How many BigtableSessions are opened. Each HBase Connection has a single BigtableSession.
Counter	google-cloud-bigtable.grpc.channel.active	How many lower-level gRPC/Netty channels are opened. Each BigtableSession has many gRPC channels.

General RPC metrics

Type	Name	Description
Counter	google-cloud-bigtable.grpc.rpc.active	The number of remote procedure calls (RPCs) that are currently active.
Meter	google-cloud-bigtable.grpc.rpc.performed	RPC throughput.

Data method metrics

Data method metrics are collected for the following data methods:

• ReadRows: Implements gets and scans.
• MutateRow: Implements puts and deletes.
• MutateRows: Implements bulk writes.
• CheckAndMutateRow: Implements HBase's checkAnd* methods.
• ReadModifyWrite: Implements HBase's Append and Increment methods.
• SampleRowKeys: Retrieves region information that is used for MapReduce operations.

Type	Name	Description
Timer	google-cloud-bigtable.grpc.method.[METHOD_TYPE].operation.latency	The length of time that individual operations take. Operations include the total amount of latency of all RPCs that are performed. (Usually only one RPC is performed. Client-side retries can cause the same RPC to be performed more than once if there is a transient error.)
Timer	google-cloud-bigtable.grpc.method.ReadRows.firstResponse.latency	The length of time that it takes to receive the first response to a scan request.
Meter	google-cloud-bigtable.grpc.method.[METHOD_TYPE].retries.performed	The number of retries that were performed.
Meter	google-cloud-bigtable.grpc.method.[METHOD_TYPE].failures	The number of non-retryable failures.
Meter	google-cloud-bigtable.grpc.method.[METHOD_TYPE].retries.exhausted	The number of times that retrying was aborted because too many retries had failed.

Bulk metrics

Bulk metrics are provided for methods that return more than one response, such as a bulk write.

Type	Name	Description
Meter	google-cloud-bigtable.scanner.results	The throughput of individual rows returned by a scan.
Meter	google-cloud-bigtable.bulk-mutator.mutations.added	The throughput of individual mutations added for each MutateRows request.
Meter	google-cloud-bigtable.bulk-mutator.mutations.retried	The number of individual mutations retried over time.

Cloud Bigtable table metrics

Converting Cloud Bigtable objects to HBase objects can add to the latency of a request. The following timers can be correlated with the specified *.operation.latency timers to measure the cost of the conversion.

Type	Name	Description
Timer	google-cloud-bigtable.table.put.latency	The length of time that individual Put operations take. Correlates with google-cloud-bigtable.grpc.method.MutateRow.operation.latency.
Timer	google-cloud-bigtable.table.get.latency	The length of time that individual Get operations take. Correlates with google-cloud-bigtable.grpc.method.ReadRows.operation.latency.

Example: Metrics for a Put request

When client-side metrics are enabled, the following metrics are collected for a successful Put request that is not retried:

• Counter: google-cloud-bigtable.grpc.rpc.active
• Meter: google-cloud-bigtable.grpc.rpc.performed
• Timer: google-cloud-bigtable.grpc.method.MutateRow.operation.latency
• Timer: google-cloud-bigtable.table.put.latency

Collecting these metrics adds approximately 1 microsecond (1/1000 of a millisecond) to the Put operation. The overall Put operation could be as fast as 2 to 3 milliseconds, assuming that the operation includes about 1 KB of data.