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Merged
galderz merged 3 commits into from
Sep 17, 2026
Merged

External Async Profiler provider #7

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0a35cc9
Standalone NativeAsyncProfiler
galderz Sep 17, 2026
e02e296
Default to DWARF C stacks
galderz Sep 17, 2026
004c2ee
Update README with Async Profiler
galderz Sep 17, 2026
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34 changes: 34 additions & 0 deletions README.md
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Expand Up @@ -47,6 +47,8 @@ java -jar target/benchmarks.jar

## Profiling

### Perf

`perf` and `perfnorm` can be used just like with JMH.

JMH `perfasm` profiler is not yet fully supported,
Expand Down Expand Up @@ -88,6 +90,38 @@ Use `perf annotate -i < <file>.perfbin` to analyse hot assembly parts, e.g.
> For example: `-prof org.mendrugo.fibula.PerfDwarfProfiler:events=cycles:P`.
> This option is only available when Fibula is built with a JMH snapshot version from the master branch.

### Async Profiler

Fibula comes with a profiler provider to integrate with
[Async Profiler](https://github.com/async-profiler/async-profiler).
It is configurable with most of the options available in
[JMH's AsyncProfiler](https://github.com/openjdk/jmh/blob/master/jmh-core/src/main/java/org/openjdk/jmh/profile/AsyncProfiler.java)
with some small variations:

* There are only two available output types: `flamegraph` and `jfr`.
* The default output type is [Flame Graph](https://github.com/brendangregg/flamegraph) as HTML instead of text.
* The C stack mode is hardcoded to `dwarf` to integrate with DWARF debug symbols available in GraalVM native images.

To use this profiler build the benchmark with debug symbols:

```shell
mvn package -Ddebug=true
```

Then run the benchmark passing in the Async Profiler patch either via the `LD_PRELOAD` environment variable,
or the `libPath` configuration option:

```shell
LD_PRELOAD=/opt/async-profiler/lib/libasyncProfiler.so java -jar target/benchmarks.jar -prof org.mendrugo.fibula.NativeAsyncProfiler
# or
java -jar target/benchmarks.jar -prof org.mendrugo.fibula.NativeAsyncProfiler:libPath=/opt/async-profiler/lib/libasyncProfiler.so
```

> **IMPORTANT**:
> Make sure not to pass in `-H:-DeleteLocalSymbols` when using the Async Profiler provider.
> When local symbols are available, Async PRofiler will use those to parse the stacks instead of the DWAF info,
> and these symbols are incomplete for this use case.

## Blackholes

Both implicit and explicit blackholes are supported.
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