IBM Java on Red Hat Enterprise Linux 6: Supported levels, recommended settings and known problems

This document contains general information about supported levels, recommended settings, and known problems. when running IBM Java 6, IBM Java 5.0, or IBM Java 1.4.2 on Red Hat Enterprise Linux (RHEL) 6.

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IBM Java 6
Supported level on RHEL 6.1:

IBM Java 6 SR9

Known issues:

Chinese, Japanese, or Korean characters are not displayed correctly in GUI applications.

IBM Java 5.0
Supported level on RHEL 6:

IBM Java 5.0 SR12 FP2

Known issues:

Chinese, Japanese, or Korean characters are not displayed correctly in GUI applications.
Position for ibus composition window is incorrect.

IBM Java 1.4.2
Supported level on RHEL 6:

IBM Java 1.4.2 SR13 FP7

Recommended settings:

On Intel platforms, set the property:
JITC_COMPILEOPT=NFASTJITALLOC

Known issues:

JIT compilation problem on Intel platforms.
Chinese, Japanese, or Korean characters are not displayed correctly in GUI applications.
Position for ibus composition window is incorrect.

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glibc crash in _Unwind_IteratePhdrCallback() with IBM Java 6 on RHEL6
This problem is indicated in two ways.
1) An error message is reported:

Program terminated with signal 11, Segmentation fault.

2) A failure is reported in the stack trace, similar to the following:

#10 0x000000467869005a in abort () from /lib64/libc.so.6
#11 0x0000020000b10a7e in masterSynchSignalHandler () from <...> ibm-java-s390x-60/jre/lib/s390x/default/libj9prt24.so
#12 <signal handler called>
#13 0x00000046787b0b44 in _Unwind_IteratePhdrCallback () from /lib64/libc.so.6
#14 0x00000046787aeb66 in dl_iterate_phdr () from /lib64/libc.so.6
#15 0x00000046787b2742 in _Unwind_Find_FDE () from /lib64/libc.so.6
#16 0x0000004678a364fc in ?? () from /lib64/libgcc_s.so.1
#17 0x0000004678a37184 in ?? () from /lib64/libgcc_s.so.1
#18 0x0000004678a37258 in _Unwind_ForcedUnwind () from /lib64/libgcc_s.so.1
#19 0x0000004678827982 in __pthread_unwind () from /lib64/libpthread.so.0

This problem has been reported on zLinux 64 with RHEL6 when running IBM Java 6 SR8 FP1.

Red Hat are aware of this problem. For more information, see Red Hat Issue Tracker #646954.

Error moving system core file - abrt-hook-ccpp
This is a known problem with IBM Java 6 on RHEL6. For more information, see APAR IZ88487.

The work around is to disable the abrt service. Do this by running the following command as the root user:

service abrtd stop

JIT compilation problem on Intel 32-bit platforms with IBM Java 1.4.2 on RHEL6
This problem might cause an unexpected exception, or incorrect results. An indicator of the problem is information appearing in the stack trace, similar to the following:
java.lang.InternalError: backstepping from 0.0 to 0.0
at sun.awt.geom.Curve.compareTo(Curve.java(Compiled Code))
at sun.awt.geom.Edge.compareTo(Edge.java(Inlined Compiled Code))
at sun.awt.geom.AreaOp.pruneEdges(AreaOp.java(Compiled Code))

The problem is caused by an optimization used by the JIT compiler for allocating small objects. The optimization depends on assumptions that are not valid on RHEL6. The problem can produce different symptoms, so you should disable the JIT optimization even if you do not encounter the problem.

The work-around is to set the following environment variable:

export JITC_COMPILEOPT=NFASTJITALLOC

The work around is only required for Intel 32-bit platforms.

Chinese, Japanese, or Korean characters are not displayed properly in GUI applications.
This problem occurs when using MAWT, and has the effect that Chinese, Japanese, or Korean characters are not displayed properly in GUI applications.

On IBM Java 6 and IBM Java 5.0, the workaround is to use XAWT instead of MAWT.
On IBM Java 1.4.2, work around the problem by following the procedure outlined in APAR PM22552.

Red Hat are aware of this problem. For more information, see Red Hat Issue Tracker #604232.

Position for ibus composition window is incorrect.
This problem occurs when using the ibus input method. The effect is that the IME composition window is not displayed under the cursor position. An additional effect is that the composition window does not follow the xterm window if it is moved.

This problem only affects IBM POWER® and s390 platforms.

Red Hat are aware of this problem. For more information, see Red Hat Issue Tracker #651915.