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Merge pull request #1963 from codeflash-ai/docs/java-docs-update

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update init docs for java
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Saurabh Misra 2026-04-01 20:20:13 -07:00 committed by GitHub
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58
docs/getting-started/java-installation.mdx
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@ -15,7 +15,9 @@ keywords:
]
---
Codeflash supports Java projects using Maven or Gradle build systems. It uses a two-stage tracing approach to capture method arguments and profiling data from running Java programs, then optimizes the hottest functions.
Codeflash supports optimizing Java projects using Maven or Gradle build systems. It works in two main ways:
1. Codeflash can optimize new java code written in a Pull Request through Github Actions.
2. Codeflash can optimize real workloads end to end. It uses a two-stage tracing approach to capture method arguments and profiling data from running Java program, then optimizes the hottest functions with that data.
### Prerequisites
@ -32,16 +34,16 @@ Good to have (optional):
<Steps>
<Step title="Install Codeflash CLI">
Codeflash CLI is a Python tool. Install it with pip:
Codeflash uses Python to run its CLI. You can use uv as a package manager and installer for Python programs.
To install uv, run the following or [see these instructions](https://docs.astral.sh/uv/getting-started/installation/)
```bash
curl -LsSf https://astral.sh/uv/install.sh | sh
```
Then install Codeflash as a uv tool.
```bash
pip install codeflash
```
Or with uv:
```bash
uv pip install codeflash
uv tool install codeflash
```
</Step>
@ -56,30 +58,12 @@ codeflash init
This will:
- Detect your build tool (Maven/Gradle)
- Find your source and test directories
- Create a `codeflash.toml` configuration file
</Step>
<Step title="Verify setup">
Check that the configuration looks correct:
```bash
cat codeflash.toml
```
You should see something like:
```toml
[tool.codeflash]
module-root = "src/main/java"
tests-root = "src/test/java"
language = "java"
```
- Update your pom.xml or gradle settings with codeflash java library. The java library instruments your code and verifies correctness.
</Step>
<Step title="Run your first optimization">
Trace and optimize a running Java program:
Trace and optimize a Java program:
```bash
codeflash optimize java -jar target/my-app.jar
@ -94,27 +78,13 @@ codeflash optimize mvn exec:java -Dexec.mainClass="com.example.Main"
Codeflash will:
1. Profile your program using JFR (Java Flight Recorder)
2. Capture method arguments using a bytecode instrumentation agent
3. Generate JUnit replay tests from the captured data
3. Generate JUnit replay tests from the captured data to create a micro-benchmark.
4. Rank functions by performance impact
5. Optimize the most impactful functions
</Step>
</Steps>
## How it works
Codeflash uses a **two-stage tracing** approach for Java:
1. **Stage 1 — JFR Profiling**: Runs your program with Java Flight Recorder enabled to collect accurate method-level CPU profiling data. JFR has ~1% overhead and doesn't affect JIT compilation.
2. **Stage 2 — Argument Capture**: Runs your program again with a bytecode instrumentation agent that captures method arguments using Kryo serialization. Arguments are stored in an SQLite database.
The traced data is used to generate **JUnit replay tests** that exercise your functions with real-world inputs. Codeflash uses these tests alongside any existing unit tests to verify correctness and benchmark optimization candidates.
<Info>
Your program runs **twice** — once for profiling, once for argument capture. This separation ensures profiling data isn't distorted by serialization overhead.
</Info>
## Supported build tools
| Build Tool | Detection | Test Execution |