CodeCompiler - Compile and Run Java Program from another Java Program

Question

We are trying to build a java code compiler to create online coding tests. We are posting the source code through REST API to an endpoint. Next, we are compiling and executing the output against test files then returning results back to the client.

The challenge here is we are spinning up a process javac - compile code and java - execute code on every request which actually takes 30MB of RAM and 600 ms for every process.

This is very huge we are unable to handle the load of 1000 users on octa-core and 16GB RAM. If We get 200 requests at once, it is spawning 200 process which is heavy and other requests are queued up.

The solutions we can think of

Don't launch javac every time, reuse it but how (javac kills itself once compilation is done)?
javac should compile string input rather than from a file.

We are just curious how does the online coding competition platforms solve these problems? We are targeting only for Java. Any help is greatly appreciated.

https://www.journaldev.com/937/compile-run-java-program-another-java-program

i don't have that much experience to build a java compiler, but i'm curious to know some of the answers, 1) are you producing .java files in response? — Ryuzaki L
– Ryuzaki L, Commented Sep 14, 2018 at 16:57
@Deadpool Yup we are creating a.java file because javac needs file input. — user3205479
– user3205479, Commented Sep 14, 2018 at 16:58

Luke Woodward · Accepted Answer · 2018-09-14 19:15:46Z

3

Since Java 1.6, Java has had a programmatic API to access the Java compiler without using a subprocess. As a starting point, see the documentation for the JavaCompiler class.

answered Sep 14, 2018 at 19:15

Luke Woodward

65.3k16 gold badges94 silver badges108 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

user699848 · Accepted Answer · 2018-09-14 19:48:49Z

You can use the javax.tools.JavaCompiler class to compile the java file dynamically. Here is a code snippet to get you started.

JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);
DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<JavaFileObject>();
List<String> optionList = new ArrayList<String>();
JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager, diagnostics, optionList, null,
    fileManager.getJavaFileObjectsFromFiles(Arrays.asList(javaFiletoCompile)));
if (task.call())
{
    //success
} else
{
    //fail      
}
fileManager.close();

Collectives™ on Stack Overflow

CodeCompiler - Compile and Run Java Program from another Java Program

2 Answers 2

Comments

Comments

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Related