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[CLJ-1013] Clojure's classloader cannot handle out-of-order loading Created: 13/Jun/12  Updated: 11/Jun/16  Resolved: 11/Jun/16

Status: Closed
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Defect Priority: Major
Reporter: Edward Z. Yang Assignee: Unassigned
Resolution: Declined Votes: 1
Labels: None


Here is a minimal test-case:

import java.io.IOException;

import clojure.lang.PersistentTreeMap;
import clojure.lang.RT;

public class TestClass {

static Class y = RT.class;
//static PersistentTreeMap x = PersistentTreeMap.EMPTY;


  • @param args
  • @throws ClassNotFoundException
  • @throws IOException
    public static void main(String[] args) throws IOException, ClassNotFoundException { PersistentTreeMap x = PersistentTreeMap.EMPTY; }


This results in the exception:

Exception in thread "main" java.lang.ExceptionInInitializerError
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:247)
at clojure.lang.RT.loadClassForName(RT.java:2056)
at clojure.lang.RT.load(RT.java:419)
at clojure.lang.RT.load(RT.java:400)
at clojure.lang.RT.doInit(RT.java:436)
at clojure.lang.RT.<clinit>(RT.java:318)
at clojure.lang.PersistentTreeMap.<init>(PersistentTreeMap.java:45)
at clojure.lang.PersistentTreeMap.<clinit>(PersistentTreeMap.java:32)
at TestClass.main(TestClass.java:19)
Caused by: java.lang.NullPointerException
at clojure.lang.APersistentSet.contains(APersistentSet.java:33)
at clojure.lang.RT.contains(RT.java:700)
at clojure.core$contains_QMARK_.invoke(core.clj:1386)
at clojure.core$load_lib.doInvoke(core.clj:5255)
at clojure.lang.RestFn.applyTo(RestFn.java:142)
at clojure.core$apply.invoke(core.clj:603)
at clojure.core$load_libs.doInvoke(core.clj:5298)
at clojure.lang.RestFn.applyTo(RestFn.java:137)
at clojure.core$apply.invoke(core.clj:603)
at clojure.core$require.doInvoke(core.clj:5381)
at clojure.lang.RestFn.invoke(RestFn.java:408)
at clojure.core__init.load(Unknown Source)
at clojure.core__init.<clinit>(Unknown Source)
... 10 more

The crux of the issue appears Clojure's classloader doesn't understand how to handle out-of-order classloading.

Comment by Kevin Downey [ 18/Apr/14 12:31 AM ]

exception still happens with clojure 1.6

Comment by Stuart Halloway [ 11/Jun/16 4:27 PM ]

Clojure 1.6 added a Java API (http://clojure.github.io/clojure/javadoc/) which is the only supported way to access Clojure from a Java program. If you access Clojure vars starting with the Java API, you should not encounter this problem.

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