[GROOVY-9601] Parsing text into a class became much slower under Groovy 3.x

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.4
• Fix Version/s: 4.0.0-alpha-1, 3.0.5
• Component/s: Compiler
• Environment: Openjdk 11
• Assignee: Eric Milles
• Reporter: Fabian Depry
• Created: 19/Jun/20 13:38
• Updated: 23/Jul/20 14:16
• Resolved: 09/Jul/20 02:21

Description

Our Java application needs to execute dynamically generated Groovy code and we use the GroovyClassLoader to create a class from that generated code.

When we tried to upgrade to Groovy 3.x we noticed a huge bump in the time it takes to create those dynamic classes (it became 10 times slower for some of them).

Here is a very simple example of how we use the class loader:

package lab;

import groovy.lang.GroovyClassLoader;

public class GroovySpeedLab {

    public static void main(String[] args) {
        StringBuilder buf = new StringBuilder();
        buf.append("package lab\r\n");
        buf.append("\r\n");
        buf.append("import groovy.transform.CompileStatic\r\n");
        buf.append("\r\n");
        buf.append("@CompileStatic\r\n");
        buf.append("class MyClass {\r\n");
        for (int i = 0; i < 1000; i++) {
            buf.append("\r\n");
            buf.append("    public void myMethod").append(i).append("() {\r\n");
            buf.append("        println('method ").append(i).append(" invoked...')\r\n");
            buf.append("    }\r\n");
        }
        buf.append("}\r\n");

        long start = System.currentTimeMillis();
        new GroovyClassLoader().parseClass(buf.toString());
        System.out.println("Done parsing in " + (System.currentTimeMillis() - start) + "ms");
    }
}

While this runs very quickly (because the methods are trivial), it it still consistently 50% slower with 3.x (but I am including this example mainly to show our use-case, not to focus on its speed difference).

Our real application has much more complex classes (and many of them) and its initialization went from a couple of minutes to 10+ minutes.

Is there another way to parse a given Groovy class without taking such a big performance hit with the new version of Groovy?

Note that we also use many small Script objects created by calling GroovyShell.parse() and we noticed the same performance hit for those (I assume it uses the same mechanism under the hood).