scalarization

Project contains my experiments with Escape Analysis and Scalar Replacement optimization in JVM. It contains set of scenarios and a small framework to run them.

How to build

mvn clean package

There are 3 modules right now: core contains infrastructure (execution framework), lab contains actual scenarios, junit-integration is experimental, it contains draft of allocation scenarios run with junit/hamcrest

How to run

(Assuming you have $JAVA_HOME pointing to java installation you want to test)

Go to lab module, and run:

chmod u+x scripts/run-all.sh
scripts/run-all.sh [results folder]

This will run all scenarios under ru.cheremin.scalarization.lab package, for all parameters space. Results will be stored in results folder, file per scenario. But this will take quite long: ~10 hours right now on my laptop.

More targeted run will look like this:

$JAVA_HOME/bin/java -Xmx64m -Xms64m -XX:+UseSerialGC -server  ...\
		-Dscenario=ru.cheremin.scalarization.lab.plain.ControlFlowScenario \
		-Dtarget-directory=results \
		 -jar target/benchmarks.jar

This will run specific scenario (ru.cheremin.scalarization.lab.plain.ControlFlowScenario) for all parameters space, which is not too big for this scenario, so it takes only 10-15 minutes. If you want to run from IDE, you should use ru.cheremin.scalarization.ForkingMain as main class, with all parameters above

And most targeted run will look like this:

$JAVA_HOME/bin/java -Xmx64m -Xms64m -XX:+UseSerialGC -server ...\
		-Dscenario=ru.cheremin.scalarization.lab.plain.ControlFlowScenario \
		-Dscenario.use-type=ACCUMULATE_IN_LOOP \
		-Dscenario.size=0 \
 		 -cp target/benchmarks.jar \
 		 ru.cheremin.scalarization.infra.AllocationBenchmarkMain

Here I run specific scenario with specific parameters.

Scenario parameters (-Dscenario.use-type=ACCUMULATE_IN_LOOP -Dscenario.size=0) are different for each scenario (scenario.size is more or less universal, it is used by many, but not all, scenarios)

How to create scenario

Scenario is a class, which extends ru.cheremin.scalarization.AllocationScenario. You can pause at this point in the beginning, and try. Without parameters, there is little difference between running scenario with ForkingMain or AllocationBenchmarkMain runners, so better to run with AllocationBenchmarkMain, since it allows you to debug (ForkingMain forks dedicated jvm process for each scenario run, making debugging harder)

Next option is to specify parameters space for scenario. In you scenario class you should specify

@ScenarioRunArgs
public static List<ScenarioRun> parametersToRunWith() {
	...
}

(method name is not important, @ScenarioRunArgs annotation is a key). ScenarioRun class contains list of additional JVM options to append/override before run the scenario. JVM options could be something like -Dname=value (JvmArg.SystemProperty), or any other JVM flag/option -- e.g. -XX:InlineSmallCode=2000 (JvmArg.JvmExtendedProperty). There are bunch of helpers for making list of parameters:

@ScenarioRunArgs
public static List<ScenarioRun> parametersToRunWith() {
	return crossJoin(
			allOf( BUILDER_TYPE_KEY, BuilderType.values() ),
			allOf( SIZE_KEY, 0, 1, 4, 128 ),

			asList(
					new JvmExtendedProperty( "FreqInlineSize", "325" ),
					new JvmExtendedProperty( "FreqInlineSize", "500" )
			)
	);
}

(from EqualsBuilderScenario). Here I build scenario space as "cube" with builderType side going though all BuilderType.values(), size side going through [0, 1, 4, 128], and -XX:FreqInlineSize going through [325, 500]: 2 * 4 * 2 = 16 runs in total. If you run your scenario with ForkingMain, it will append additional "dimension" to your parameters space: -XX:+EliminateAllocations / -XX:-EliminateAllocations (this is default "control" to verify is scalar replacement really in charge of cleaned allocations), so in this case it will be 32 runs in total

As you can see, most parameters are passed in scenario code with system properties, as this way you could read them into public static final fields, which, in turn, allows JIT to aggressively inline them. Again, look at EqualsBuilderScenario for an example.