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System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) · 课时

手动检测最佳实践

了解何时以及如何应用手动检测，以精细控制可观测性数据。学习使用自定义属性丰富追踪数据。

第 2 / 4 课11 个步骤

手动检测最佳实践 是 CoddyKit 上的免费 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 课时。 这是第 2 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Manual Instrumentation Intro

Welcome! In this lesson, we'll dive into manual instrumentation with OpenTelemetry. While auto-instrumentation is great for quick wins, manual control gives you precision.

Manual instrumentation allows you to record highly specific details about your application's internal operations. This is crucial for debugging complex business logic or custom components.

Why Manual Over Auto?

Auto-instrumentation automatically collects data from common libraries and frameworks. However, it can't know your unique application logic.

  • Custom Logic: Instrument specific functions or blocks of code.
  • Business Context: Add attributes relevant to your business domain.
  • Fine-Grained Control: Define exact span boundaries and relationships.
  • Missing Coverage: Cover areas where auto-instrumentation doesn't reach.

Creating Your First Span

A span represents a single operation within a trace. To create one manually, you need a Tracer, which is obtained from the OpenTelemetry SDK.

Here's how to start a new span. Remember to always end your spans!

import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.Tracer;
import io.opentelemetry.api.trace.SpanBuilder;
import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.sdk.OpenTelemetrySdk;
import io.opentelemetry.sdk.trace.SdkTracerProvider;

public class ManualSpanDemo {
  public static void main(String[] args) {
    // Setup OpenTelemetry SDK (simplified for demo)
    SdkTracerProvider sdkTracerProvider = SdkTracerProvider.builder().build();
    OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
        .setTracerProvider(sdkTracerProvider)
        .buildAndRegisterGlobal();

    Tracer tracer = openTelemetry.getTracer("my-app", "1.0.0");

    // Start a new span
    Span span = tracer.spanBuilder("MyCustomOperation").startSpan();

    try {
      System.out.println("Executing custom operation...");
      // Simulate work
      Thread.sleep(100);
    } catch (InterruptedException e) {
      Thread.currentThread().interrupt();
    } finally {
      // Always end the span!
      span.end();
      System.out.println("Span ended.");
    }
  }
}

Activating Spans with Scope

For a span to be part of the current trace context (and for child spans to automatically link to it), it needs to be active. The best way to manage this is using a Scope with a try-with-resources statement.

This ensures the span is automatically set as active and ended when the block exits.

import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.Tracer;
import io.opentelemetry.api.trace.Scope;
import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.sdk.OpenTelemetrySdk;
import io.opentelemetry.sdk.trace.SdkTracerProvider;

public class ActiveSpanDemo {
  public static void main(String[] args) {
    SdkTracerProvider sdkTracerProvider = SdkTracerProvider.builder().build();
    OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
        .setTracerProvider(sdkTracerProvider)
        .buildAndRegisterGlobal();

    Tracer tracer = openTelemetry.getTracer("my-app", "1.0.0");

    Span parentSpan = tracer.spanBuilder("ParentOperation").startSpan();
    try (Scope parentScope = parentSpan.makeCurrent()) { // Parent span is active
      System.out.println("Parent operation started.");

      Span childSpan = tracer.spanBuilder("ChildOperation").startSpan(); // Automatically links to parent
      try (Scope childScope = childSpan.makeCurrent()) {
        System.out.println("Child operation executing...");
        Thread.sleep(50);
      } catch (InterruptedException e) {
        Thread.currentThread().interrupt();
      } finally {
        childSpan.end();
        System.out.println("Child operation ended.");
      }

      Thread.sleep(50);
    } catch (InterruptedException e) {
      Thread.currentThread().interrupt();
    } finally {
      parentSpan.end();
      System.out.println("Parent operation ended.");
    }
  }
}

Adding Custom Attributes

Attributes are key-value pairs that provide contextual information about a span. They are vital for making your traces searchable and understandable.

You can add attributes to a span using span.setAttribute(). Use descriptive keys and relevant values.

import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.Tracer;
import io.opentelemetry.api.trace.Scope;
import io.opentelemetry.api.common.AttributeKey;
import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.sdk.OpenTelemetrySdk;
import io.opentelemetry.sdk.trace.SdkTracerProvider;

public class SpanAttributesDemo {
  public static void main(String[] args) {
    SdkTracerProvider sdkTracerProvider = SdkTracerProvider.builder().build();
    OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
        .setTracerProvider(sdkTracerProvider)
        .buildAndRegisterGlobal();

    Tracer tracer = openTelemetry.getTracer("my-app", "1.0.0");

    Span span = tracer.spanBuilder("ProcessOrder").startSpan();
    try (Scope scope = span.makeCurrent()) {
      System.out.println("Processing order...");
      // Add attributes for order details
      span.setAttribute("order.id", "XYZ789");
      span.setAttribute("customer.email", "user@example.com");
      span.setAttribute(AttributeKey.longKey("item.count"), 3L);

      Thread.sleep(150);
    } catch (InterruptedException e) {
      Thread.currentThread().interrupt();
    } finally {
      span.end();
      System.out.println("Order processed. Span ended with attributes.");
    }
  }
}

Recording Span Events

Events are timestamped messages associated with a span. They are useful for marking significant moments or logging specific actions that occur during the span's lifetime, without creating new child spans.

Think of them as mini-logs within your trace, adding more detail to a specific operation.

import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.Tracer;
import io.opentelemetry.api.trace.Scope;
import io.opentelemetry.api.common.Attributes;
import io.opentelemetry.api.common.AttributeKey;
import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.sdk.OpenTelemetrySdk;
import io.opentelemetry.sdk.trace.SdkTracerProvider;

public class SpanEventsDemo {
  public static void main(String[] args) {
    SdkTracerProvider sdkTracerProvider = SdkTracerProvider.builder().build();
    OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
        .setTracerProvider(sdkTracerProvider)
        .buildAndRegisterGlobal();

    Tracer tracer = openTelemetry.getTracer("my-app", "1.0.0");

    Span span = tracer.spanBuilder("UserLogin").startSpan();
    try (Scope scope = span.makeCurrent()) {
      System.out.println("User login initiated...");
      span.addEvent("AuthenticationStarted");

      Thread.sleep(80);
      // Add an event with attributes
      span.addEvent("DatabaseCheck", Attributes.of(
          AttributeKey.stringKey("db.query"), "SELECT * FROM users WHERE id=?"
      ));

      Thread.sleep(70);
      span.addEvent("AuthenticationSuccessful");

    } catch (InterruptedException e) {
      Thread.currentThread().interrupt();
    } finally {
      span.end();
      System.out.println("User login span ended with events.");
    }
  }
}

Handling Errors in Spans

It's crucial to mark spans as failed when an error occurs. This helps quickly identify problematic operations in your system.

You can set a span's status to ERROR and record the exception that caused the failure. This provides rich context for debugging.

import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.Tracer;
import io.opentelemetry.api.trace.StatusCode;
import io.opentelemetry.api.trace.Scope;
import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.sdk.OpenTelemetrySdk;
import io.opentelemetry.sdk.trace.SdkTracerProvider;

public class SpanErrorDemo {
  public static void main(String[] args) {
    SdkTracerProvider sdkTracerProvider = SdkTracerProvider.builder().build();
    OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
        .setTracerProvider(sdkTracerProvider)
        .buildAndRegisterGlobal();

    Tracer tracer = openTelemetry.getTracer("my-app", "1.0.0");

    Span span = tracer.spanBuilder("CriticalFunction").startSpan();
    try (Scope scope = span.makeCurrent()) {
      System.out.println("Executing critical function...");
      // Simulate an error condition
      if (Math.random() > 0.5) {
        throw new RuntimeException("Simulated critical failure!");
      }
      System.out.println("Critical function completed successfully.");

    } catch (Exception e) {
      System.out.println("Error caught: " + e.getMessage());
      span.setStatus(StatusCode.ERROR, "Function failed");
      span.recordException(e);
    } finally {
      span.end();
      System.out.println("Critical function span ended.");
    }
  }
}

Best Practices for Spans

To get the most out of manual instrumentation, follow these guidelines:

  • Granularity: Create spans for meaningful units of work, not every single line of code.
  • Meaningful Names: Use clear, low-cardinality names (e.g., user.login, db.query).
  • Rich Attributes: Add relevant business and technical context as attributes.
  • Always End Spans: Use try-with-resources or explicit span.end() in a finally block.
  • Avoid Over-instrumentation: Too many spans can add overhead. Focus on critical paths.

Linking Spans Explicitly

While makeCurrent() handles most parent-child linking, sometimes you need to explicitly link spans. This is common in asynchronous scenarios or when integrating with non-instrumented systems.

You can use SpanBuilder.setParent() or setNoParent() to control the parent-child relationship.

import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.Tracer;
import io.opentelemetry.api.trace.SpanContext;
import io.opentelemetry.api.trace.SpanKind;
import io.opentelemetry.api.trace.TraceFlags;
import io.opentelemetry.api.trace.TraceState;
import io.opentelemetry.context.Context;
import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.sdk.OpenTelemetrySdk;
import io.opentelemetry.sdk.trace.SdkTracerProvider;

public class ExplicitLinkDemo {
  public static void main(String[] args) {
    SdkTracerProvider sdkTracerProvider = SdkTracerProvider.builder().build();
    OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
        .setTracerProvider(sdkTracerProvider)
        .buildAndRegisterGlobal();

    Tracer tracer = openTelemetry.getTracer("my-app", "1.0.0");

    // Imagine a span from an external system, represented by its context
    SpanContext externalContext = SpanContext.create(
        "1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d", // Trace ID
        "0000000000000001", // Span ID
        TraceFlags.getDefault(), TraceState.getDefault()
    );

    // Create a new span that links to this external context
    Span linkedSpan = tracer.spanBuilder("ProcessingExternalMessage")
        .setParent(Context.current().with(Span.wrap(externalContext))) // Link to external context
        .setSpanKind(SpanKind.CONSUMER) // Indicate it's a message consumer
        .startSpan();

    try {
      System.out.println("Processing message from external system...");
      linkedSpan.setAttribute("message.id", "MSG-123");
      Thread.sleep(100);
    } catch (InterruptedException e) {
      Thread.currentThread().interrupt();
    } finally {
      linkedSpan.end();
      System.out.println("Linked span ended.");
    }
  }
}

Manual Instrumentation Check

You're implementing a new feature that calculates a user's loyalty points. You want to instrument this specific calculation to track its duration and the final points awarded. Which of the following is the most appropriate way to record the final points using manual OpenTelemetry instrumentation?

在交互式课程中回答

Recap: Manual Control

In this lesson, we explored manual instrumentation with OpenTelemetry. You learned:

  • When to choose manual over auto-instrumentation for fine-grained control.
  • How to create, activate, and end spans.
  • The power of attributes for adding rich context to your traces.
  • How to use events to mark specific moments within a span.
  • Best practices for handling errors and linking spans explicitly.

Mastering manual instrumentation gives you unparalleled visibility into your application's unique logic and performance.

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常见问题解答

「手动检测最佳实践」课时是免费的吗？

是的 — 「手动检测最佳实践」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 课程的其余内容，请升级到 CoddyKit PRO。 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 课程共包含 4 节课。

「手动检测最佳实践」这节课中我会学到什么？

了解何时以及如何应用手动检测，以精细控制可观测性数据。学习使用自定义属性丰富追踪数据。 你通过在浏览器中直接运行的动手代码来练习 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry)，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 需要有经验吗？

无需任何先前经验。CoddyKit 上的 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 2 节课，共 4 节。

「手动检测最佳实践」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 课中编写并运行代码吗？

能。每节 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

此课程中的所有课时

  1. 自动检测技术
  2. 手动检测最佳实践
  3. 上下文传播与行李
  4. 跨度属性、事件与状态
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