> For the complete documentation index, see [llms.txt](https://docs.flopsar.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.flopsar.com/7/user-guide/observing-and-diagnosing/method-execution-tree.md).

# Method Execution Tree

The method execution tree is the drill-down view of a **single** recorded invocation: the nested calls that produced it, with time spent in each method. Open it from [Data Browser](/7/user-guide/observing-and-diagnosing/data-browser.md) or from a correlated row in [Data Correlation](/7/user-guide/observing-and-diagnosing/data-correlation.md).

How the tree is assembled — and why it can be shallower than the real call stack — is explained in [Key Concepts & Glossary](/7/user-guide/key-concepts-and-glossary.md#assembled-stacks-why-what-you-see-can-differ-from-reality).

{% hint style="info" %}
**Screenshot placeholder:** Call Stack Details. Tab bar: Execution Stack, Spectrum, Top, Critical Path, CPU Efficiency, Fan-In/Out, Exceptions, AI Assistant. Flame-style bars for one invocation.
{% endhint %}

The header shows the application, instance, thread, recorded call count versus total calls, and exception count. Bars are color-coded:

* gray — signature only
* green — captured parameters
* red — exceptions
* amber — parameters and exceptions

Click a bar for **Details** (class, method, duration, CPU share, parent/root share) and the parameter inspector. From details you can zoom to that bar, search the method in the tree, list callees, download class bytes, or add the class to a profile clipboard.

{% hint style="warning" %}
[WebGL support](/7/overview/supported-platforms-and-requirements.md#workstation) is required for the Execution Stack canvas.
{% endhint %}

## Execution Stack

A flame-style chart of the call tree over wall-clock time. Use search, zoom, and optional tooltips. This is the primary view for walking a slow or failing request.

## Spectrum

Aggregated statistics for every distinct method in this stack: unique methods, total calls, exceptions, and total self-time. The table is sortable; click a row to jump to that method on the Execution Stack.

## Top

Three rankings of the same stack:

* **Groups** — time distribution by instrumentation group (the groups you assigned on Allow rules).
* **Top Duration** — slowest method calls by wall-clock time.
* **Top Self-Time** — methods that spent the most time in their own body. See [Self-time](/7/user-guide/key-concepts-and-glossary.md#self-time).

## Critical Path

The single most expensive branch from the root down to a leaf: path length, total duration, average CPU efficiency, and exceptions on that path. Use it when you want the one chain that explains most of the latency.

## CPU Efficiency

Compares CPU time to wall-clock duration per method:

* **CPU-bound** — efficiency above 80%
* **Mixed** — 50–80%
* **Blocking** — below 50% (likely waiting on I/O, locks, or remote calls)

Requires **CPU Time** on the monitoring profile; otherwise CPU columns stay empty.

## Fan-In/Out

How connected methods are inside this stack:

* **High fan-out** — five or more unique callees (orchestrators, dispatchers).
* **High fan-in** — three or more unique callers (shared utilities, hot helpers).

## Exceptions

Every exception recorded on this invocation: total count, unique types, and which methods threw. Open a type to inspect the stack trace. If the execution completed cleanly, the tab shows an empty state.

## AI Assistant

When the assistant is enabled and you have **Use AI assistant**, this tab analyzes the current stack. See [AI Assistant](/7/user-guide/observing-and-diagnosing/ai-assistant.md).