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https://issues.apache.org/jira/browse/GROOVY-9742?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17943515#comment-17943515
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ASF GitHub Bot commented on GROOVY-9742:
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paulk-asert opened a new pull request, #2185:
URL: https://github.com/apache/groovy/pull/2185

   …Put() hang (additional flexibility)




> GroovyClassLoader.parseClass() StampedCommonCache.getAndPut() hang
> ------------------------------------------------------------------
>
>                 Key: GROOVY-9742
>                 URL: https://issues.apache.org/jira/browse/GROOVY-9742
>             Project: Groovy
>          Issue Type: Bug
>          Components: groovy-runtime
>    Affects Versions: 3.0.5
>         Environment: Java version AdoptOpenJDK (build 25.262-b10, mixed mode)
> Gradle version 6.6.1
> Groovy version 3.0.5 
>            Reporter: Chiang Seng Chang
>            Assignee: Daniel Sun
>            Priority: Major
>             Fix For: 5.0.0-alpha-13
>
>         Attachments: g3cl.tar.gz
>
>
> We have an IDE-like app which allows our coders to develop groovy scripts and 
> classes.
>  Essentially, the coders would write groovy sources and test them in the app.
> We made a CustomClassLoader which is created and destroyed for each test run, 
> so that the app need no be restarted every time there is code change.
> In Groovy 3.0.5, the GroovyClassLoader's cache is refactored to use 
> StampedCommonCache, which does not support recursion.
> This is the distilled simplified version of our CustomClassLoader:
> {noformat}
> public class CustomGroovyClassLoader extends ClassLoader {
>     public CustomGroovyClassLoader(ClassLoader parent) {
>         super(parent);
>         groovyClassLoader = new GroovyClassLoader(this);
>     }
>     private final File srcDir = new File("./src/main/groovy");
>     private final GroovyClassLoader groovyClassLoader;
>     @Override
>     protected Class<?> loadClass(String name, boolean resolve)
>                                  throws ClassNotFoundException {
>         synchronized (getClassLoadingLock(name)) {
>             Class<?> c = doFindClass(name);
>             if (c != null) {
>                 if (resolve) {
>                     resolveClass(c);
>                 }
>                 return c;
>             }
>         }
>         return super.loadClass(name, resolve);
>     }
>     private Class<?> doFindClass(String name) {
>         File classFile = new File(srcDir, name.replace('.', '/') + ".groovy");
>         if (classFile.exists()) {
>             try {
>                 System.out.println("PARSE\t: " + name);
>                 Class<?> clz = groovyClassLoader.parseClass(classFile);
>                 System.out.println("PARSED\t: " + clz);
>                 return clz;
>             }
>             catch (IOException e) {
>                 throw new RuntimeException(e);
>             }
>         }
>         return null;
>     }
> }
> {noformat}
> Essentially, it uses the GroovyClassLoader.parseClass() for our test classes.
> Here are the 2 classes to demonstrate the issue:
> {noformat}
> package foo
> import groovy.transform.CompileStatic
> @CompileStatic
> interface Bar {}
> {noformat}
> {noformat}
> package foo
> import groovy.transform.CompileStatic
> @CompileStatic
> class Foo implements Bar {}
> {noformat}
> And the test harness:
> {noformat}
> package foo;
> public class TestHarness {
>     public static void main(String[] args) throws Exception {
>         ClassLoader pcl = TestHarness.class.getClassLoader();
>         CustomGroovyClassLoader ccl = new CustomGroovyClassLoader(pcl);
>         Class<?> clz = ccl.loadClass("foo.Foo");
>         System.out.println("DONE\t: " + clz);
>     }
> }
> {noformat}
> The harness attempt to load Foo.groovy.
> The sequence of events would be:
>  # CustomClassLoader.loadClass(Foo)
>  # GroovyClassLoader.parseClass(Foo.groovy)
>  # sourceCache.getAndPut(Foo)
>  # Since Foo implements Bar, CustomClassLoader is called to load Bar
>  # which in turn calls GroovyClassLoader.parseClass(Bar.groovy)
>  # and sourceCache.getAndPut(Bar)
>  # Since StampedCommonCache does not support recursion, the loading hangs.
> The attached project can be run using ./gradlew run to demonstrate the 
> hanging.
> It seems to me that the GroovyClassLoader needs to support recursion for this 
> use case.
> Or perhaps the CustomClassLoader is implemented wrongly?
> Groovy 2.5.12 does not have this issue because its GroovyClassLoader uses 
> ConcurrentCommonCache.
>  
>  
>  



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