RFR 8187222 : ClassLoader.getSystemClassLoader not clear if recursive initialization leads to ISE or unspecified error

[mandy chung]

On 11/30/17 1:35 PM, Brent Christian wrote:
> Hi,
>
> Please review the following change:
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8187222
> Webrev: http://cr.openjdk.java.net/~bchristi/8187222/webrev.00/
>

Thanks for fixing it.

This is indeed a bug that should throw ISE when 
ClassLoader.getSystemClassLoader is called during the initialization of 
the system class loader, as the spec states.

line 1921: I suggest to revise the message to make it clearer:
      "getSystemClassLoader cannot be called during the system class 
loader instantiation"

In ClassLoader::initSystemClassLoader (line 1971), when the exception is 
thrown via Constructor::newInstance, it would be good to the cause of an 
InvocationTargetException like:

+                Throwable t = e;
+                if (e instanceof InvocationTargetException) {
+                    t = e.getCause();
+                }
+                throw new Error(t.getMessage(), t);

InitSystemLoaderTest.java verifies a working custom system class 
loader.  This recursive custom system loader test fits better as a new 
test rather a test case in InitSystemLoaderTest.java.

I suggest to rename ThrowingCustomLoader as RecursiveSystemLoader and 
make it as jtreg test with a static void main (maybe it should validate 
what getSystemClassLoader returns).    It can be made simpler e.g. line 
30-31, 45-47 and 54 are not needed.

Mandy