$ cd jruby
$ ant clean jar compile-test run-junit-precompiled
...
    [junit] junit.framework.TestListener: startTest(test_io)
    [junit] # To suppress the following error report, specify this argument
    [junit] # after -XX: or in .hotspotrc: SuppressErrorAt=/handles.cpp:46
    [junit] #
    [junit] # A fatal error has been detected by the Java Runtime Environment:
    [junit] #
    [junit] # Internal Error (/home/ct232829/hsx/hotspot-comp/7092712/src/share/vm/runtime/handles.cpp:46), pid=27921, tid=3171941232
    [junit] # assert(SharedSkipVerify || obj->is_oop()) failed: sanity check
    [junit] #
    [junit] # JRE version: 7.0_02-b07
    [junit] # Java VM: Java HotSpot(TM) Client VM (23.0-b01-internal-fastdebug mixed mode linux-x86 )
    [junit] # Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
    [junit] #
    [junit] [thread -1059394704 also had an error]
    [junit] # An error report file with more information is saved as:
    [junit] # [thread -1059394704 also had an error]
    [junit] #
    [junit] # If you would like to submit a bug report, please visit:
    [junit] # http://bugreport.sun.com/bugreport/crash.jsp
    [junit] #

Stack traces from hs_err file:

--------------- T H R E A D ---------------

Current thread (0xbdf2e400): JavaThread "RubyThread-195: test/test_io_generated_test.rb:4" daemon [_thread_in_vm, id=21000, stack(0xbd0af000,0xbd100000)]

Stack: [0xbd0af000,0xbd100000], sp=0xbd0fe66c, free space=317k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x766ad7] VMError::report_and_die()+0x197
V [libjvm.so+0x2fb6e4] report_vm_error(char const*, int, char const*, char const*)+0x64
V [libjvm.so+0x3949cd] HandleArea::allocate_handle(oopDesc*)+0x8d
V [libjvm.so+0x259270] Handle::Handle(oopDesc*)+0x40
V [libjvm.so+0x3ea19e] InterpreterRuntime::resolve_get_put(JavaThread*, Bytecodes::Code)+0x6ae
j java.lang.invoke.CallSite.setTargetNormal(Ljava/lang/invoke/MethodHandle;)V+2
J java.lang.invoke.MutableCallSite.setTarget(Ljava/lang/invoke/MethodHandle;)V
j org.jruby.runtime.invokedynamic.InvocationLinker.invocationFallback(Lorg/jruby/runtime/invokedynamic/JRubyCallSite;Lorg/jruby/runtime/ThreadContext;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/builtin/IRubyObject;Ljava/lang/Stri
ng;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+152
j $_dot_.test.test_io.block_44$RUBY$test_multithreaded_writes(L$_dot_/test/test_io;Lorg/jruby/runtime/ThreadContext;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/buil
tin/IRubyObject;+41
j $_dot_$test$test_io$block_44$RUBY$test_multithreaded_writes.call(Lorg/jruby/runtime/ThreadContext;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;
+9
j org.jruby.runtime.CompiledBlock.yield(Lorg/jruby/runtime/ThreadContext;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/RubyModule;ZLorg/jruby/runtime/Binding;Lorg/jruby/runtime/Block$Type;Lorg/jruby/r
untime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+70
j org.jruby.runtime.BlockBody.call(Lorg/jruby/runtime/ThreadContext;[Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/Binding;Lorg/jruby/runtime/Block$Type;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+27
j org.jruby.runtime.Block.call(Lorg/jruby/runtime/ThreadContext;[Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+15
j org.jruby.RubyProc.call(Lorg/jruby/runtime/ThreadContext;[Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+59
j org.jruby.RubyProc.call(Lorg/jruby/runtime/ThreadContext;[Lorg/jruby/runtime/builtin/IRubyObject;)Lorg/jruby/runtime/builtin/IRubyObject;+7
j org.jruby.internal.runtime.RubyRunnable.run()V+100
j java.lang.Thread.run()V+11
v ~StubRoutines::call_stub
V [libjvm.so+0x3f7c2c] JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*)+0x65c
V [libjvm.so+0x606309] os::os_exception_wrapper(void (*)(JavaValue*, methodHandle*, JavaCallArguments*, Thread*), JavaValue*, methodHandle*, JavaCallArguments*, Thread*)+0x19
V [libjvm.so+0x3f7f42] JavaCalls::call_virtual(JavaValue*, KlassHandle, Symbol*, Symbol*, JavaCallArguments*, Thread*)+0x182
V [libjvm.so+0x3f8171] JavaCalls::call_virtual(JavaValue*, Handle, KlassHandle, Symbol*, Symbol*, Thread*)+0x61
V [libjvm.so+0x46feb2] thread_entry(JavaThread*, Thread*)+0x92
V [libjvm.so+0x71d964] JavaThread::thread_main_inner()+0xf4
V [libjvm.so+0x610681] java_start(Thread*)+0x121
C [libpthread.so.0+0x69e9] start_thread+0xc9

Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
j java.lang.invoke.CallSite.setTargetNormal(Ljava/lang/invoke/MethodHandle;)V+2
J java.lang.invoke.MutableCallSite.setTarget(Ljava/lang/invoke/MethodHandle;)V
j org.jruby.runtime.invokedynamic.InvocationLinker.updateInvocationTarget(Ljava/lang/invoke/MethodHandle;Lorg/jruby/runtime/invokedynamic/JRubyCallSite;Lorg/jruby/RubyModule;Ljava/lang/String;Lorg/jruby/runtime/callsite/CacheEntry;ZI)Ljava/lang/invoke/MethodHandle;+214
j org.jruby.runtime.invokedynamic.InvocationLinker.invocationFallback(Lorg/jruby/runtime/invokedynamic/JRubyCallSite;Lorg/jruby/runtime/ThreadContext;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/builtin/IRubyObject;Ljava/lang/String;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+152
j $_dot_.test.test_io.block_44$RUBY$test_multithreaded_writes(L$_dot_/test/test_io;Lorg/jruby/runtime/ThreadContext;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+41
j $_dot_$test$test_io$block_44$RUBY$test_multithreaded_writes.call(Lorg/jruby/runtime/ThreadContext;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+9
j org.jruby.runtime.CompiledBlock.yield(Lorg/jruby/runtime/ThreadContext;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/RubyModule;ZLorg/jruby/runtime/Binding;Lorg/jruby/runtime/Block$Type;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+70
j org.jruby.runtime.BlockBody.call(Lorg/jruby/runtime/ThreadContext;[Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/Binding;Lorg/jruby/runtime/Block$Type;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+27
j org.jruby.runtime.Block.call(Lorg/jruby/runtime/ThreadContext;[Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+15
j org.jruby.RubyProc.call(Lorg/jruby/runtime/ThreadContext;[Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+59
j org.jruby.RubyProc.call(Lorg/jruby/runtime/ThreadContext;[Lorg/jruby/runtime/builtin/IRubyObject;)Lorg/jruby/runtime/builtin/IRubyObject;+7
j org.jruby.internal.runtime.RubyRunnable.run()V+100
j java.lang.Thread.run()V+11
v ~StubRoutines::call_stub