We're seeing the problem listed below in a client-facing application
and it's causing us a not inconsiderable amount of grief.

Tried 1.3.1_01 but when we tried that we found
even more problems, happening more regularly (see attached). I sent
this report to Sun at the time (in September), to which they replied
there wasn't enough information so they wouldn't accept it as a bug.
However, I looked at Sun's website recently and found the following,
which has been accepted, which seems identical to the attached bug,

http://developer.java.sun.com/developer/bugParade/bugs/4525303.html

Unexpected Signal : 11 occurred at PC=0xee61a288
Function name=JVM_GetClassName
Library=/sbcimp/run/tp/sun/jre/v1.3.1/lib/sparc/server/libjvm.so


Dynamic libraries:
0x10000
/sbcimp/run/tp/sun/jre/v1.3.1/bin/../bin/sparc/
/java
0xef770000 /usr/lib/libthread.so.1
0xef7b0000 /usr/lib/libdl.so.1
0xef680000 /usr/lib/libc.so.1
0xef740000 /usr/platform/SUNW,Ultra-2/lib/libc_psr.so.1
0xee400000 /sbcimp/run/tp/sun/jre/v1.3.1/lib/sparc/server/libjvm.so
0xef620000 /usr/lib/libCrun.so.1
0xef600000 /usr/lib/libsocket.so.1
0xef500000 /usr/lib/libnsl.so.1
0xef5d0000 /usr/lib/libm.so.1
0xef650000 /usr/lib/libw.so.1
0xef5a0000 /usr/lib/libmp.so.2
0xef4c0000
/sbcimp/run/tp/sun/jre/v1.3.1/lib/sparc/native_threads/libhpi.so
0xef490000 /sbcimp/run/tp/sun/jre/v1.3.1/lib/sparc/libverify.so
0xef450000 /sbcimp/run/tp/sun/jre/v1.3.1/lib/sparc/libjava.so
0xeebd0000 /sbcimp/run/tp/sun/jre/v1.3.1/lib/sparc/libzip.so
0xee2e0000 /sbcimp/run/tp/sun/jre/v1.3.1/lib/sparc/libnet.so
0xee2c0000 /usr/lib/nss_nis.so.1

Local Time = Thu Sep 27 14:33:12 2001
Elapsed Time = 342771
#
# HotSpot Virtual Machine Error : 11
# Error ID : 4F530E43505002CC 01
# Please report this error at
# http://java.sun.com/cgi-bin/bugreport.cgi
#
# Java VM: Java HotSpot(TM) Server VM (1.3.1-b24 mixed mode)
#

Spoke to Chris Phillips he suggested the follwing:

for 1.3.1_01 is probably bug 4525303

The is the subject of anesc so a backport to 1.3.1 will occur
if the fix can be found/identified.