microbench/README.md

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# Microbenchmarks for Apache Pulsar

This module contains microbenchmarks for Apache Pulsar.

## Running the benchmarks

The benchmarks are written using [JMH](http://openjdk.java.net/projects/code-tools/jmh/). To compile & run the benchmarks, use the following command:

```bash
# Compile everything for creating the shaded microbenchmarks.jar file
mvn -Pcore-modules,microbench,-main -T 1C clean package

# run the benchmarks using the standalone shaded jar in any environment
java -jar microbench/target/microbenchmarks.jar
```

For fast recompiling of the benchmarks (without compiling Pulsar modules) and creating the shaded jar, you can use the following command:

```bash
mvn -Pmicrobench -pl microbench clean package
```

### Running specific benchmarks

Display help:

```shell
java -jar microbench/target/microbenchmarks.jar -h
```

Listing all benchmarks:

```shell
java -jar microbench/target/microbenchmarks.jar -l
```

Running specific benchmarks:

```shell
java -jar microbench/target/microbenchmarks.jar ".*BenchmarkName.*"
```

Running specific benchmarks with machine-readable output and saving the output to a file:

```shell
java -jar microbench/target/microbenchmarks.jar -rf json -rff jmh-result-$(date +%s).json ".*BenchmarkName.*" | tee jmh-result-$(date +%s).txt
```

The `jmh-result-*.json` file can be used to visualize the results using [JMH Visualizer](https://jmh.morethan.io/).

Checking what benchmarks match the pattern:

```shell
java -jar microbench/target/microbenchmarks.jar ".*BenchmarkName.*" -lp
```

Profiling benchmarks with [async-profiler](https://github.com/async-profiler/async-profiler):

```shell
# example of profiling with async-profiler
# download async-profiler from https://github.com/async-profiler/async-profiler/releases
LIBASYNCPROFILER_PATH=$HOME/async-profiler/lib/libasyncProfiler.dylib
java -jar microbench/target/microbenchmarks.jar -prof async:libPath=$LIBASYNCPROFILER_PATH\;output=flamegraph\;dir=profile-results ".*BenchmarkName.*"
```

When profiling on Mac OS, you might need to add `\;event=itimer` to the `-prof` argument since it's the only [async profiler CPU sampling engine that supports Mac OS](https://github.com/async-profiler/async-profiler/blob/master/docs/CpuSamplingEngines.md#summary). The default value for `event` is `cpu`.

It's possible to add options to the async-profiler that aren't supported by the JMH async-profiler plugin. This can be done by adding `rawCommand` option to the `-prof` argument. This example shows how to add `all` (new in Async Profiler 4.1), `jfrsync` (record JFR events such as garbage collection) and `cstack=vmx` options.

```shell
java -jar microbench/target/microbenchmarks.jar -prof async:libPath=$LIBASYNCPROFILER_PATH\;output=jfr\;dir=profile-results\;rawCommand=all,jfrsync,cstack=vmx ".*BenchmarkName.*"
```