These changes will only be reflected in newly opened windows something to keep in mind if you have any command-line windows open. After adding the bin directory to your PATH , you can then simply run the test shown previously by executing:.
Although most Linux distributions and OS X include utilities for extracting both types of files, TGZ files are preferable because files extracted from them include permission settings, something that is not the case with ZIP files. If you have root privileges on the system where you want JRuby installed, you should install JRuby based on whatever standards already exist. This will facilitate upgrades later:. Once the bin directory has been added to your PATH , you can test the install by running a simple Ruby script:.
Building JRuby from Source. Using Both Ruby and JRuby. Use the RubyGems support built into JRuby. To install a package, run:. For example, to install the Ruby on Rails web framework, use:.
RubyGems is the standard package management and distribution system for Ruby packages. Although some gems are specific to the C Ruby implementation or JRuby, most are compatible with any Ruby implementation. Common RubyGems commands include install , query , update , uninstall , and rdoc.
The full list can be output by using the help command:. You have Ruby and JRuby installed on the same computer and want to ensure that a Ruby script is processed by the correct interpreter. Use the -S command-line argument for the ruby and jruby executables. For example, RubyGems is traditionally invoked with a command like:. Popular Ruby packages such as Rake, Ruby on Rails, and RubyGems include their own executable Ruby scripts that most guides, both online and print, instruct you to invoke directly.
Because there are so many variables, this recipe prescribes using a single, consistent method, passing the script name through the -S command-line argument to either the ruby or jruby executables. This advice is particularly significant in the context of the RubyGems script, gem. To create a new Rails application, you could run either:. You can see this by passing environment to the gem script:.
Managing Packages with RubyGems. You already have a number of RubyGems installed and want to use those gems from JRuby without reinstalling the gems. This value can be seen in the output of gem environment , where it is referred to as the installation directory:. Whereas some RubyGems are implemented entirely in Ruby, many are implemented in a combination of Ruby and C or, in a growing number of cases, Ruby and Java. However, those implemented in a mixture can only be installed using a compatible interpreter.
The list of supported platforms for each interpreter can be seen in the output of gem environment. Because the RubyGems runtime knows this list of supported platforms, it is possible to mix gems supporting different platforms in the same directory; the runtime will select the appropriate libraries. You want to write Ruby code that uses one or more Java classes. First, you need to tell JRuby that you will be referencing Java classes from your Ruby code.
Do this by including an include declaration at the top of your Ruby file:. The syntax for referencing a specific Java class depends on the package in which the class resides. For packages starting with java , javax , org , and com , you can simply reference the fully qualified class name or use an import statement, as shown in Example To do this, pass a block to the function.
In this case, you could provide the appropriate alias using a case statement, as seen in Example JRuby makes referencing Java classes relatively natural from the perspective of a Java developer.
For the most commonly used packages, you can use import just as you would in Java code. When calling methods on a Java class, JRuby handles some type conversion for you—instances of basic Ruby classes such as FixNum , Float , and String are converted to instances of the corresponding Java classes when passed to Java objects. JRuby includes implementations of the java.
List and java. Map interfaces for handling Ruby Array and Hash objects. Example includes a combination of Java and Ruby code, which demonstrates this functionality. JRuby provides access to public static methods and variables through the :: operator. Example shows how you would access the static methods and variables of the Java Math class. You need to pass a Ruby array to a method that accepts a Java array of a specific type. For example, creating an array of javax.
StreamSource objects would be done like this:. Primitives, as well as java. String , have Ruby symbols assigned to them. For example, to create an array of int primitives:.
For example, calling a method through Java Management Extensions JMX involves passing two arrays to the invoke method of javax.
MBeanServer , one of Object instances, storing the method parameters, and one of String instances, storing the method signature. To call invoke from JRuby, you would do something like this:. This path can be relative to the current working directory:.
Although this is an extremely useful feature of JRuby, it should be used with caution, especially if you use absolute paths that are platform- and installation-specific. Yet all is not lost. An interesting aspect of this feature of JRuby is that the JAR file is added to the classpath dynamically, while the application is running.
Example includes a method that creates a path to a JAR file in a local Maven repository. Example shows a Ruby class that extends the Java Thread class and overrides the run method. The fact that the same syntax is used to extend both Java and Ruby classes is an important design feature of JRuby, as it furthers the seamless integration between the two languages. One notable exception to this recipe is classes that use Java 5 generics. Currently, these cannot be subclassed with Ruby classes.
Abstract Java classes can also be extended by Ruby classes. Examples and show an example of an abstract Java class and a concrete Ruby class that extends the former. The hello method, declared abstract in the Java class, is implemented in the Ruby class.
Create your class with method names that match the names in the Java interface. As of version 1. Duck typing, seen in many dynamic languages, including Ruby, means that the type of an object is determined based on the methods implemented by the object. Example shows this technique in action as a new Java thread by passing the constructor an object that implements the java. Runnable interface. The HelloThread class contains a zero-argument run method that corresponds to the method defined in java.
JRuby requires no additional type information in the HelloThread class to instantiate the Thread object. One case is when a duck-typed JRuby object is passed as an argument to an overloaded Java method. This provides the JRuby interpreter with enough information about the object to execute the correct method. In Example , the HelloThread class is assigned the Runnable interface. As a result, JRuby calls the desired exec method and runnable is output to the console.
Because Ruby scripts implicitly create a top-level class, it is not even necessary to define a new class to implement a Java interface. This functionality, seen in Example , can be especially useful when prototyping and testing. Ruby modules are a natural fit to help implement Java interfaces. Also Trinidad is known to work well, though may have a slightly larger memory footprint:. You will need to change the commands in your Procfile to start your app using the JRuby server of your choice.
An example for the Puma webserver would be:. The majority of JDBC drivers are very mature and have been heavily optimized for speed. You will need to remove the regular pg gem from your Gemfile:. While many gems in the community are JRuby compatible, you may be relying on some that are not. Many gem authors choose to enable JRuby tests on TravisCI , so you could check compatibility using their most recent builds. If no records exist of whether a project will run on JRuby you can always try installing it through bundler:.
Even if a gem installs correctly there may be subtle bugs that exist in the library. It is always a good idea to run tests on your project and perform some manual testing locally to confirm compatibility. There have been reports of incompatibilities using different versions of the twitter-bootstrap-rails gem with JRuby. You may need to upgrade to a more recent version of the gem. Your simplest answer for both JRuby and TruffleRuby would be to set it up to use a single process to do everything.
In JRuby, it is trivial to start up a separate, isolated JRuby instance within the same process:. The code given will run in the same process but a completely different JRuby environment.
If you managed to get your CI run to use a single process, I would be surprised if it was not as fast or faster than standard C-based Ruby. Note: The article does cover --dev and I did put together a single process example in update 2. The results are way better, but still slower. AppCDS is a way to significantly improve startup speed without impacting total runtime performance. I imagine the IO problems you were likely seeing is due to a lot of back and forth communication between the app and the disk, what happens if you kill that off?
The feedback from the JRuby and TruffleRuby people has been amazing. They have been offering suggestions and asking for tickets and reproduction steps. Spreading the word about Earthly. Host of CoRecursive podcast. Deploying an application once meant provisioning a virtual machine, ensuring security protocols were in place, and installing the required frameworks—a comp And like most programming languages, it has variables.
You use these shell variables whene Performance of JVM Ruby runtimes in small tests looks good but is it too good to be true? A Flame Graph shows most time is File Access. Write static files, pages, and posts. Returns nothing. Read Site data from disk and load it into internal data structures. Jekyll :: Hooks. Render the site to the destination.
This time most of the time is Liquid Template Rendering. Adam Gordon Bell. Azure Functions Deployment for Node.
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