JarCastingzipkin-reporter-java
Zipkin Reporter buffers and sends trace data collected from tracer libraries to a Zipkin compatible backend.
This repository includes a Java reporting library with transport-specific senders. Transport options include HTTP, Apache ActiveMQ, Apache Kafka, gRPC, RabbitMQ and Scribe (Apache Thrift). Requires JRE 6 or later.
Usage
These components can be called when spans have been recorded and ready to send to zipkin.
Encoder
The span encoder is a specialized form of Zipkin's Codec, which only deals with encoding one span. It is also extensible in case the type of span reported is not zipkin2.Span
Reporter
After recording an operation into a span, it needs to be reported out of process. There are two builtin reporter implementations in this library, although you are free to create your own.
The simplest mechanism is printing out spans as they are reported.
Reporter.CONSOLE.report(span);
AsyncReporter
AsyncReporter is how you actually get spans to zipkin. By default, it waits up to a second before flushes any pending spans out of process via a Sender.
reporter = AsyncReporter.create(URLConnectionSender.create("http://localhost:9411/api/v2/spans"));
// Schedules the span to be sent, and won't block the calling thread on I/O
reporter.report(span);
Brave
Those using the Brave library can skip overhead by using AsyncZipkinSpanHandler.
Ex.
sender = URLConnectionSender.create("http://localhost:9411/api/v2/spans");
zipkinSpanHandler = AsyncZipkinSpanHandler.create(sender); // don't forget to close!
tracingBuilder.addSpanHandler(zipkinSpanHandler);
See zipkin-reporter-brave for more details.
Spring Beans
If you are trying to trace legacy applications, you may be interested in Spring XML Configuration. This allows you to trace legacy Spring 2.5+ applications without any custom code.
Tuning
By default AsyncReporter starts a thread to flush the queue of reported spans. Spans are encoded before enqueuing so it is easiest to relate the backlog as a function of bytes.
Here are the most important properties to understand when tuning.
| Property | Description |
|---|---|
queuedMaxBytes |
Maximum backlog of span bytes reported vs sent. Corresponds to ReporterMetrics.updateQueuedBytes. Default 1% of heap |
messageMaxBytes |
Maximum bytes sendable per message including overhead. Default 500,000 bytes (500KB). Defined by Sender.messageMaxBytes |
messageTimeout |
Maximum time to wait for messageMaxBytes to accumulate before sending. Default 1 second |
closeTimeout |
Maximum time to block for in-flight spans to send on close. Default 1 second |
Dealing with span backlog
When messageTimeout is non-zero, a single thread is responsible for bundling spans into a message for the sender. If you are using a blocking sender, a surge of reporting activity could lead to a queue backup. This will show in metrics as spans dropped. If you get into this position, switch to an asynchronous sender (like kafka), or increase the concurrency of your sender.
Spikes of high CPU could be due to encoding many spans, caused indirectly by a large messageTimeout or messageMaxBytes. Consider lowering the messageMaxBytes if this occurs, as it will result in less work per message.
Sender
The sender component handles the last step of sending a list of encoded spans onto a transport. This involves I/O, so you can call Sender.check() to check its health on a given frequency.
Sender is used by AsyncReporter, but you can also create your own if you need to.
class CustomReporter implements Flushable {
--snip--
URLConnectionSender sender = URLConnectionSender.json("http://localhost:9411/api/v2/spans");
Callback callback = new IncrementSpanMetricsCallback(metrics);
// Is the connection healthy?
public boolean ok() {
return sender.check().ok();
}
public void report(Span span) {
pending.add(SpanBytesEncoder.JSON_V2.encode(span));
}
@Override
public void flush() throws IOException {
if (pending.isEmpty()) return;
List<byte[]> drained = new ArrayList<byte[]>(pending.size());
pending.drainTo(drained);
if (drained.isEmpty()) return;
sender.sendSpans(drained, callback).execute();
}
Protocol Buffers Encoding
By default, senders use json v2 encoding, which is easy to understand, but twice as large as binary encoding for normal spans. If you are running a recent (2.8+) version of Zipkin server, consider Protocol Buffers when you want to optimize for least size.
You can switch to proto3 encoding like so:
sender = KafkaSender.newBuilder()
.encoding(Encoding.PROTO3)
.bootstrapServers("192.168.99.100:9092")
.build()
Legacy Encoding
By default, senders use json v2 encoding, which is easy to understand and twice as efficient as the v1 json encoding. However, it relies on recent (1.31+) versions of zipkin server.
You can switch to v1 encoding like so:
reporter = AsyncReporter.builder(URLConnectionSender.create("http://localhost:9411/api/v1/spans"))
.build(SpanBytesEncoder.JSON_V1);
Artifacts
All artifacts publish to the group ID "io.zipkin.zipkin.reporter2". We use a common release version for all components.
Library Releases
Releases are uploaded to Sonatype which synchronizes with Maven Central
Library Snapshots
Snapshots are uploaded to Sonatype after commits to master.
Version alignments
When using multiple reporter components, you'll want to align versions in one place. This allows you to more safely upgrade, with less worry about conflicts.
You can use our Maven instrumentation BOM (Bill of Materials) for this:
Ex. in your dependencies section, import the BOM like this:
<dependencyManagement>
<dependencies>
<dependency>
<groupId>io.zipkin.reporter2</groupId>
<artifactId>zipkin-reporter-bom</artifactId>
<version>${zipkin-reporter.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
Now, you can leave off the version when choosing any supported instrumentation. Also any indirect use will have versions aligned:
<dependency>
<groupId>io.zipkin.reporter2</groupId>
<artifactId>zipkin-sender-okhttp3</artifactId>
</dependency>
With this in place, you can use the property zipkin-reporter.version to override dependency versions coherently. This is most commonly to test a new feature or fix.
Note: If you override a version, always double check that your version is valid (equal to or later) than what you are updating. This will avoid class conflicts.
