Hi,
I got a question: Clojure seems to create poopillions of
DynamicClassLoader instances. Why does it do that? Could I try
patching it so that it creates less of them? I need this cause I ran
into trouble working with JNI.
I looked at the Clojure source rev 1323. I'm no expert, this is my
first look at the sources, but the following struck me as hack-ish:
(from Compiler.java, shortened slightly)
public static Object eval(Object form) throws Exception{
if(true)//!LOADER.isBound())
makeClassLoader();
To me, that looks like for evaluating _every form_, a new classloader
gets created. Isn't that a bit much? Also, it looks "temporary" that
the if() has its condition commented out and replaced with
true ... :-/ So Clojure's behavior seems to have been different at
some point in the past.
Thanks a bunch for your opinions.
Cheers
Hendrik
Details:
I'm asking because I was loading a native library through JNI. The
rule here (apparently) is that you can load a library through only one
classloader, not the same library through several loaders.
For example, this program fails:
(System/load "/home/hk/inotify-java-0.1/build/native/libinotify-
java.so")
(System/load "/home/hk/inotify-java-0.1/build/native/libinotify-
java.so")
I feel that the program should work. Apparently Clojure creates new
classloaders between line 1 and 2. An equivalent Java program does
work (the first System.load() loads the library, the second sees the
library is already loaded and does nothing).
This is the exact error message:
$ cat t3.clj
(System/load "/home/hk/inotify-java-0.1/build/native/libinotify-
java.so")
(System/load "/home/hk/inotify-java-0.1/build/native/libinotify-
java.so")
(println "42")
$ java -jar /home/hk/clojure-svn-2/clojure.jar t3.clj
java.lang.UnsatisfiedLinkError: Native Library /home/hk/inotify-
java-0.1/build/native/libinotify-java.so already loaded in another
classloader (t3.clj:0)
at clojure.lang.Compiler.eval(Compiler.java:4533)
at clojure.lang.Compiler.load(Compiler.java:4846)
at clojure.lang.Compiler.loadFile(Compiler.java:4813)
at clojure.main$load_script__5685.invoke(main.clj:206)
at clojure.main$script_opt__5716.invoke(main.clj:258)
at clojure.main$main__5740$fn__5742.invoke(main.clj:333)
at clojure.main$main__5740.doInvoke(main.clj:328)
at clojure.lang.RestFn.invoke(RestFn.java:413)
at clojure.lang.Var.invoke(Var.java:346)
at clojure.lang.AFn.applyToHelper(AFn.java:173)
at clojure.lang.Var.applyTo(Var.java:463)
at clojure.main.main(main.java:39)
Caused by: java.lang.UnsatisfiedLinkError: Native Library /home/hk/
inotify-java-0.1/build/native/libinotify-java.so already loaded in
another classloader
at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1743)
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1674)
at java.lang.Runtime.load0(Runtime.java:770)
at java.lang.System.load(System.java:1005)
at user$eval__4.invoke(t3.clj:2)
at clojure.lang.Compiler.eval(Compiler.java:4522)
... 11 more
$
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