# stack-walker-benchmark

**Repository Path**: mirrors_ceki/stack-walker-benchmark

## Basic Information

- **Project Name**: stack-walker-benchmark
- **Description**: Microbenchmark of Java 9 StackWalker API
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2021-01-12
- **Last Updated**: 2026-05-31

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

Java 9 StackWalker API microbenchmark
=====================================

The goal of this microbenchmark is to see how fast the `StackWalker` API introduced in Java9.

= Implementation details

This benchmark is composed of two files.
`StackTraceBenchmark` measures how long it takes to retrieve the 5 last elements of a stack trace without actually using them.
It serves as the baseline for the second experiment.
`FileAndLineNumberBenchmark` measures how long it takes to get the file name and line number of those elements.

All the information contained in this README file are based on JDK 9 build 125.

The implementation of `StackFrameInfo.java` converts a `StackFrame` into a `StackTraceElement` before the file name and line number can be retrieved.
Each call of `getFileName()`, `getMethodName()` and `getLineNumber()` creates a new `StackTraceElement`.
Getting the class name, method name and bytecode index do not require such a conversion.
Therefore, `FileAndLineNumberBenchmark` contains the following methods:

* `exception` gets those information by building a new `Exception` and getting its stack trace
* `stackwalkerWithFileNameAndLineNumber` gets those information by calling the three methods `getFileName()`, `getMethodName()` and `getLineNumber()`
* `stackwalkerWithExplicitStackTraceElement` does the same but first converts the `StackFrame` to a `StackTraceElement` and reuses it
* `stackwalkerWithClassMethodAndBCI` only gets the class name, method name and bytecode index
* `stackwalkerWithClassAndBCI` only gets the class name and bytecode index

= Results

The `StackWalker` API is faster than the typical way by a 2x factor.
However, calling `getFileName()`, `getMethodName()` and `getLineNumber()` on `StackFrame()` imply a substantial cost.

[source,bash]
----
$ java -jar target/microbenchmarks.jar -f 5 -wi 10 -i 10
[...]
# Run complete. Total time: 00:10:24

Benchmark                                                            Mode  Cnt      Score     Error  Units
StackTraceBenchmark.exception                                        avgt   50  17002,587 ± 355,071  ns/op
StackTraceBenchmark.stackwalker                                      avgt   50   4456,895 ± 109,627  ns/op
FileAndLineNumberBenchmark.exception                                 avgt   50  17907,933 ± 336,197  ns/op
FileAndLineNumberBenchmark.stackwalkerWithFileNameAndLineNumber      avgt   50  11225,741 ± 216,263  ns/op
FileAndLineNumberBenchmark.stackwalkerWithExplicitStackTraceElement  avgt   50   8989,665 ± 134,605  ns/op
FileAndLineNumberBenchmark.stackwalkerWithClassMethodAndBCI          avgt   50   6955,292 ± 169,572  ns/op
FileAndLineNumberBenchmark.stackwalkerWithClassAndBCI                avgt   50   4620,220 ± 115,719  ns/op
----

= Todo

- Find out if using the class name and BCI allow to uniquely identify a method and line in a file.

= Licence

This project is licenced under the MIT licence.  See the LICENSE file for details.