JDK-6612680 : Remove classloader dependency on jkernel
  • Type: Enhancement
  • Component: deploy
  • Sub-Component: deployment_toolkit
  • Affected Version: 6u5,6u10
  • Priority: P2
  • Status: Closed
  • Resolution: Fixed
  • OS: generic,windows
  • CPU: generic
  • Submitted: 2007-10-03
  • Updated: 2011-02-18
  • Resolved: 2011-02-18
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JDK 7
7 b74Fixed
Related Reports
Duplicate :  
JDK-6833260 - Revisit DownloadManager initialization if it should only begin after VM completes its initialization
Relates :  
JDK-6888546 - restore System.initializeSystemClasses
Relates :  
JDK-6888880 - JKernel VM to inject the sun.jkernel.DownloadManager as a boot classloader hook
Relates :  
JDK-6888893 - Revisit the special handling in java.awt.color.ICC_Profile and java.util.zip.ZipEntry
Relates :  
JDK-7016707 - Remove the BootClassLoaderHook for jkernel support
Relates :  
JDK-6825019 - DownloadManager should not be loaded and referenced for full JRE
Relates :  
JDK-6888802 - sun.misc.BootClassLoaderHook.getBootstrapPaths stack overflow
Description
java.lang.ClassLoader and sun.misc.Launcher have explicit dependencies on the Kernel code.  While the performance impact of this is minimal (the calls basically amount to nops when the JRE is complete), it's still undesirable.

We should restructure this so there is e.g. a system property that controls how these classes delegate, and then have the launcher set this system property to point to the relevant Kernel code when running in a Kernel environment.
Comments
EVALUATION Note that Kernel has also been completely removed from JDK 7
18-02-2011
SUGGESTED FIX Changeset: c499401bc138 Author: mchung Date: 2009-10-05 18:15 -0700 URL: http://hg.openjdk.java.net/jdk7/tl/jdk/rev/c499401bc138 6612680: Remove classloader dependency on jkernel Summary: Add a new sun.misc.BootClassLoaderHook that DownloadManager will implement Reviewed-by: alanb, forax, igor ! make/sun/jkernel/Makefile ! src/share/classes/java/awt/color/ICC_Profile.java ! src/share/classes/java/lang/ClassLoader.java ! src/share/classes/java/util/zip/ZipEntry.java ! src/share/classes/sun/jkernel/DownloadManager.java + src/share/classes/sun/misc/BootClassLoaderHook.java ! src/share/classes/sun/misc/Launcher.java ! src/share/classes/sun/misc/VM.java ! src/share/native/sun/misc/VM.c
06-10-2009
EVALUATION To eliminate the static dependency on jkernel, this fix adds a boot classloader hook interface that is invoked in the ClassLoader findClass, getSystemResource, and other methods. The hook is null by default. The jkernel VM will call the static DownloadManager.setBootClassLoaderHook() method and only the jkernel environment will have a non-null boot class loader hook. Since jkernel is a separate build including the bundles and VM, the jkernel VM is a reasonable place to inject the DownloadManager as the boot class loader hook (see 6888880). This fix depends on 6888880 for jkernel to work.
06-10-2009