Btrace

BTrace

**Safe, dynamic tracing for Java applications**

[](https://github.com/btraceio/btrace/actions) [](https://github.com/btraceio/btrace/releases/latest) [](https://codecov.io/github/btraceio/btrace?branch=develop)

BTrace dynamically instruments running Java applications to inject tracing code at runtime. No restarts. No recompilation. Production-safe.

**Quick links:** [Quick Reference](docs/QuickReference.md) · [Step-by-Step Tutorial](docs/GettingStarted.md)

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Why BTrace?

• Zero downtime - Attach to running JVMs without restart
• Production safe - Verified scripts can't crash your application
• Flexible probes - Method entry/exit, timings, field access, allocations
• Low overhead - Bytecode injection with minimal performance impact

Supported Java Versions

BTrace 3.0 runs on Java 8–25+. Running BTrace against a JVM older than Java 17 is deprecated: it continues to work throughout 3.x but emits a deprecation warning. Support for Java < 17 will be removed in the next major release (4.0). See the [migration guide](docs/Migration-2.x-to-3.0.md) for details on upgrading from BTrace 2.x.

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Get Started in 30 Seconds

# Install via JBang (easiest)
curl -Ls https://sh.jbang.dev | bash -s - app setup

# Add the BTrace JBang catalog (one time)
jbang catalog add --name btraceio https://raw.githubusercontent.com/btraceio/jbang-catalog/main/jbang-catalog.json

# Trace slow methods in your running app
jbang btrace@btraceio -n 'com.myapp.*::* @return if duration>100ms { print method, duration }' $(pgrep -f myapp)

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Trace Anything

**Method timing:**

btrace -n 'java.sql.Statement::execute* @return { print method, duration }' 

**Exception tracking:** ```sh