IBM SDK Java Technology Edition V6 (J9 VM2.6): Current news

The documentation to support IBM SDK for Java version 6 is available in an IBM Information Center. Supplementary information is available for the following releases:

• Service refresh 5 fix pack 2
• Service refresh 5 fix pack 1
• Service refresh 5
• Service refresh 2

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Service refresh 5 fix pack 2

This fix pack includes a change to the default value for the RMI property java.rmi.server.useCodebaseOnly from false to true, which might cause unexpected errors for applications that use RMI. For more information, see http://docs.oracle.com/javase/7/docs/technotes/guides/rmi/enhancements-7.html.

On Windows, improvements are made to the way that Runtime.exec decodes command strings. However, applications specifying commands that contain spaces in the program name, or that use quotation marks incorrectly, might fail to start. For more information, including guidance on resolving problems, see http://www.oracle.com/technetwork/java/javase/7u21-relnotes-1932873.html#jaruntime.

For further information about other security fixes in this release, see Security Alerts.

The SDK and JRE includes the Olson timezone update tzdata2013b. For information about the daylight saving time changes included in this update, see Olson time zone updates in the IBM SDK for Java.

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Service refresh 5 fix pack 1

This fix pack contains a security fix for the Oracle security vulnerability, CVE-2013-0169. For any further security fixes in this release, see Security alerts.

A security enhancement is included to correctly validate certificates on jar files of applications. After upgrading, a CertificateException occurs for any applications in one of the following scenarios:

• The application jar is not properly signed.
• The application jar has incorrect certificates.
• A certificate in the certificate chain is revoked.

To avoid these exceptions, make sure that your application jars are signed with valid certificates before upgrading from an earlier release. This issue relates to APAR IV38456.

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Service refresh 5

The following change is included in this release:

Non-blocking registration of interested operations with selectors on the AIX operating system

In this release, the implementation of the registration of interested operations with the java.nio.channels.Selector class has been modified to avoid blocked threads.

In previous releases, this implementation could cause blocking of threads on the AIX® operating system. If a Java application used the java.nio.channels.SelectionKey.interestOps() method to register an interested operation with a Selector object that was engaged in a polling operation, the registering thread could be blocked. A thread that is blocked in this way can cause the application to hang or timeout. The following Java stack traces from such a situation show that the first thread is performing a poll operation, and the second thread is blocked:

3XMTHREADINFO      "Thread-2" TID:0x31E65800, j9thread_t:0x31C9764C, state:R, prio=5
3XMTHREADINFO1            (native thread ID:0x2AA00A5, native priority:0x5, native policy:UNKNOWN)
4XESTACKTRACE          at sun/nio/ch/PollArrayWrapper.poll0(Native Method)
4XESTACKTRACE          at sun/nio/ch/PollArrayWrapper.poll(PollArrayWrapper.java:116)
4XESTACKTRACE          at sun/nio/ch/PollSelectorImpl.doSelect(PollSelectorImpl.java:57)
4XESTACKTRACE          at sun/nio/ch/SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
4XESTACKTRACE          at sun/nio/ch/SelectorImpl.select(SelectorImpl.java:80)
4XESTACKTRACE          at sun/nio/ch/SelectorImpl.select(SelectorImpl.java:84)
4XESTACKTRACE          at BlockIntOpsReg.run(BlockIntOpsReg.java:18)
4XESTACKTRACE          at java/lang/Thread.run(Thread.java:735)


3XMTHREADINFO      "main" TID:0x30A65500, j9thread_t:0x301162D4, state:B, prio=5
3XMTHREADINFO1            (native thread ID:0x14A005F, native priority:0x5, native policy:UNKNOWN)
4XESTACKTRACE          at sun/nio/ch/SelectionKeyImpl.nioInterestOps(SelectionKeyImpl.java:103)
4XESTACKTRACE          at sun/nio/ch/SelectionKeyImpl.interestOps(SelectionKeyImpl.java:65)
4XESTACKTRACE          at BlockIntOpsReg.main(BlockIntOpsReg.java:40)

This thread blocking was caused by the pollset implementation using a Java cache of limited size to store requests for registration of interested operations. When the cache reached its size limit, the implementation attempted to register all the requests in the Java cache into the native AIX pollset cache, which could result in blocked threads. From this release, the Java cache size is unlimited, and interested operations are registered just before the next poll operation, to avoid blocking of threads.

For more information about I/O polling on the AIX operating system, see the following developerWorks article: Efficient I/O event polling through the pollset interface on AIX.

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Service refresh 2

The following change is included in this release:

KeyboardFocusManager implementation

This change relates to Oracle security vulnerability CVE-2012-0502.
The KeyboardFocusManager specification explicitly allows a single, global KeyboardFocusManager for all applets. Some public methods are unsafe for such implementations.
As a result of the fix, the following methods now throw a java.lang.SecurityException if they are invoked on a java.awt.KeyboardFocusManager that is not the current java.awt.KeyboardFocusManager for the calling thread's context:

• java.awt.KeyboardFocusManager.setGlobalFocusOwner(Component focusOwner)
• java.awt.KeyboardFocusManager.clearGlobalFocusOwner()
• java.awt.KeyboardFocusManager.setGlobalPermanentFocusOwner(Component PermanentFocusOwner)
• java.awt.KeyboardFocusManager.setGlobalFocusedWindow(Window focusedWindow)
• java.awt.KeyboardFocusManager.setGlobalActiveWindow(Window activeWindow)
• java.awt.KeyboardFocusManager.setGlobalCurrentFocusCycleRoot(Container newFocusCycleRoot)

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