GROOVY-11478: Enable GroovyClassLoader to be ParallelCapable (backpor…

…t to 3_0_X)

src/main/java/groovy/lang/GroovyClassLoader.java

@@ -78,6 +78,7 @@
 import java.util.Collection;
 import java.util.Enumeration;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicInteger;
 
 /**
  * A ClassLoader which can load Groovy classes. The loaded classes are cached,
@@ -105,8 +106,11 @@ public class GroovyClassLoader extends URLClassLoader {
     private final CompilerConfiguration config;
     private String sourceEncoding;
     private Boolean recompile;
-    // use 1000000 as offset to avoid conflicts with names from the GroovyShell
-    private static int scriptNameCounter = 1000000;
+    private static final AtomicInteger scriptNameCounter = new AtomicInteger(1_000_000); // 1,000,000 avoids conflicts with names from the GroovyShell
+
+    static {
+        registerAsParallelCapable();
+    }
 
     private GroovyResourceLoader resourceLoader = new GroovyResourceLoader() {
         public URL loadGroovySource(final String filename) throws MalformedURLException {
@@ -272,8 +276,7 @@ public Class parseClass(String text) throws CompilationFailedException {
     }
 
     public synchronized String generateScriptName() {
-        scriptNameCounter++;
-        return "script" + scriptNameCounter + ".groovy";
+        return "script" + scriptNameCounter.getAndIncrement() + ".groovy";
     }
 
     public Class parseClass(final Reader reader, final String fileName) throws CompilationFailedException {