Here's the deal: Assume there's an applet that takes a classname as
a parameter. It does a Class.forName() on that parameter, then does
an instanceof test against an interface I. Two instances of this applet
appear on an HTML page, one is passed class A, one class B.

Interface I is at the top of the inheritance hierarchy; there's a class
C that implements I. Both A and B inherit from C.

If you load this HTML page from file:, no problem. If you load it from
javaweb (such that getting the bytes takes a bit of time), hard crash
every time. This happens on both Windows NT and Solaris. Synchronize on
a static object around the Class.forName() call, and the problem goes
away. If the instanceof test is against C instead of I, no crash. If
C is taken out of the inheritance hierarchy, no crash.

Here's what the C stack looks like:

   start_func(0xef719c00, 0xed9c2658, 0xef6fe45c, 0x0, 0x0, 0x0)
   ThreadRT0(0xed9c2658, 0xef730970, 0x0, 0x0, 0x0, 0x0)
   execute_java_dynamic_method(0xecbe1ca4, 0xed9c2658, 0xef73096c,
 0xef730970, 0xef733000, 0x0)
   do_execute_java_method_vararg(0xecbe1ca4, 0xef730971, 0x0, 0x0,
 0x0, 0x3a5450)
   finish_invokevirtual(0x39e107, 0xecbe1ca4, 0x3a558c, 0x3a5550,
 0x39da10, 0x3a5560)
   is_instance_of()
   --- Signal SIGSEGV raised ---
   --- Signal SIGSEGV raised ---sysAbort(0x0, 0xecbe2000, 0xecbe1698,
 0xb, 0x0, 0x0)
  _lwp_kill(0x0, 0x6, 0x3921, 0xef72b5bc, 0x16, 0x0)


The code to reproduce this is in ~billf/public_html/instanceof/.



Original bug:

    See http://parched/~brucew/BUGS/CoreBug2 to recreate problem where HJB
    core dumps when applets can't load a class file.
    See attached file for Segmentation Violation details.
    See ~brucew/public_html/BUGS/CoreBug2 for "core" file.

bill.foote@Eng 1997-08-07