Absolute Beginner

[Robert Calfee]

I have no Maven, no Gradle, never seen them before today when I read about Quasar's fibers and started trying to put together a project.

I'm familiar with Netbeans and wanted to set this up as a project there and experiment with fibers, but really I'm at a loss as to what needs to be done and how.

I'm running a windows system btw.

I know at the far end, I'll be marking methods with throws SuspendExecution but what are the steps between downloading the sources from git and typing up my test code?


[Robert Calfee]

All right, I did get the project to build. Though I could not get Maven to work right for me to gather the dependent jar files, I was able to locate and install them by hand.

Now I have a quasar-core.jar, but I cannot get it to instrument the test program for me

--- exec-maven-plugin:1.2.1:exec (default-cli) @ quasar ---
QUASAR WARNING: Quasar Java Agent isn't running. If you're using another instrumentation method you can ignore this message; otherwise, please refer to the Getting Started section in the Quasar documentation.
Exception in thread "main" java.lang.IllegalArgumentException: Fiber class com.paralleluniverse.quasar.FiberSample$1 has not been instrumented.
    at co.paralleluniverse.fibers.Fiber.<init>(Fiber.java:186)
    at co.paralleluniverse.fibers.Fiber.<init>(Fiber.java:225)
    at co.paralleluniverse.fibers.Fiber.<init>(Fiber.java:515)
    at com.paralleluniverse.quasar.FiberSample$1.<init>(FiberSample.java:20)
    at com.paralleluniverse.quasar.FiberSample.main(FiberSample.java:20)
------------------------------------------------------------------------
BUILD FAILURE
------------------------------------------------------------------------
Total time: 2.306s
Finished at: Tue Oct 11 13:13:56 PDT 2016
Final Memory: 7M/184M
------------------------------------------------------------------------
Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2.1:exec (default-cli) on project quasar: Command execution failed. Process exited with an error: 1 (Exit value: 1) -> [Help 1]

I know I'm missing something, just not sure what.

[victo...@gmail.com]

you need to configure the exec plugin to setup the quasar agent.

The best is to take a look at the pom demo for quasar, just generate it by following the instructions there: https://github.com/puniverse/quasar-mvn-archetype

[Robert Calfee]

I have used the mvn-archetype and achieved some success: the program will build and run in netbeans (yay!) Thanks for that.

I used the AOT option to preinstrument the classes and was experimenting with preparing a .jar file that would execute.

I collected the dependencies for quasar in a directory ./libs and have the jar file in .

 this runs:
java -cp ./libs/*;quasar-aot-1.0-SNAPSHOT.jar testgrp.QuasarIncreasingEchoApp

This does not:
java -jar quasar-aot-1.0-SNAPSHOT.jar
it gives a  java.lang.NoClassDefFoundError: co/paralleluniverse/strands/SuspendableCallable

The manifest file is attached

[pron]

This is not how you add a classpath to a JAR file. See this. You may want to look at Capsule for single-file binary deployments (there's a Maven plugin that makes the build very easy).

I would also recommend that, as a beginner, you first use the Java agent rather than AOT instrumentation, especially if you're not yet comfortable with your build tool. In general, the agent is always preferable (beginner or not); use AOT only if you have a very good reason to.

Ron

[Satej S]

Adding to what Ron mentioned, if you're using Intelli-J, it's very easy to provide a java agent. Follow the steps below assuming you have already downloaded the jar file.

1. Hit Alt-Ctrl/Command(Mac)-R and hit Edit Configuration ,
2. Add the following:  -javaagent filepathtojar.jar in the VM arguments. 

 Here is a sample of the file path : -javaagent:/Users/yourusername/Foldername/subfolder/quasar-core-0.7.2.jar 

[Robert Calfee]

Hi.

I had seen that link about class paths and jar files. I have tried just about everything I could to get the jar file to recognize the needed dependent .jars. Nothing would work.

I guess I don't understand what your mean when you say "This is not how you add a classpath to a JAR file." I included them all in the manifest individually, but it was too long, so I gathered them into a directory, as I said, that did not work either.

And in any case I do not see any way to launch the jar and the agent. Using AOT, and then one-jar worked to create a jar file that I could launch with
 java -jar quasar-aot-1.0-SNAPSHOT.jar

So my question would be: why would I not use AOT?

[pron]

On Tuesday, October 18, 2016 at 7:41:53 AM UTC+3, Robert Calfee wrote:

I guess I don't understand what your mean when you say "This is not how you add a classpath to a JAR file." I included them all in the manifest individually, but it was too long, so I gathered them into a directory, as I said, that did not work either.

The most common way is to list them all on the command line in a script. Anyway, this is what a build tool (like Maven or Gradle) is for. It will create the script or the manifest for you, even if it's long.
 

And in any case I do not see any way to launch the jar and the agent. Using AOT, and then one-jar worked to create a jar file that I could launch with
 java -jar quasar-aot-1.0-SNAPSHOT.jar

You need something to setup your command line anyway. Often people use shell scripts generated by their build tools. I recommend Capsule, as it packages everything, including all dependencies, into a single executable JAR, which automatically sets up the command line, including the agent, when you run `java -jar myapp.jar`

 

So my question would be: why would I not use AOT?

Because it makes the build more complicated and you're still a beginner with the build tool. It may also let problems in the build process introduce subtle bugs. Anyway, since you are a beginner, you should definitely use the agent first. You may switch to AOT later if you like, although I see no good reason to in most cases. But first of all, you should get comfortable with real-world projects, which require dependency management, build tools and the like. Those tools are an integral part of modern, real-world software development, not only in Java, but in all languages you'll encounter.

Ron

[Fabio Tudone]

I'll only add that AOT works at build time so clearly it can't instrument anything you don't build yourself, like (usually) 3rd-party libraries, so typically integration modules will need runtime (agent or classloader) instrumentation (unless of course you repackage dependencies yourself after AOT-instrumenting them but this is usually not very practical).

-- Fabio