When running StressRedefine with TraceRedefineClasses on we can hit this assert.
It's seem like much bigger chans of getting this error if you run more test and concurrent.

#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/home/rehn/source/jdk/vanilla-hs/hotspot/src/share/vm/oops/constantPool.hpp:498), pid=23533, tid=23761
# assert(tag_at(which).is_invoke_dynamic()) failed: Corrupted constant pool
#
# JRE version: Java(TM) SE Runtime Environment (9.0) (fastdebug build 9-internal+0-2016-05-03-153448.rehn.vanilla-hs)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 9-internal+0-2016-05-03-153448.rehn.vanilla-hs, mixed mode, tiered, compressed oops, g1 gc, linux-amd64)
# Core dump will be written. Default location: /var/cores/core.%e.%p.%h.%t
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
#

--------------- S U M M A R Y ------------

Command Line: -XX:TraceRedefineClasses=2147475455 -Xlog:disable -Xlog:all=warning:file=warnerr.%p.log::filecount=0 -agentlib:stressRedefine nsk.jvmti.RedefineClasses.StressRedefine /home/rehn/source/jdk/vanilla-hs/build/linux-x86_64-normal-server-fastdebug/images/test/hotspot/closed/tonga/bin

Host: rehn-ws, Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz, 32 cores, 31G, Fedora release 23 (Twenty Three)
Time: Tue May 3 16:02:49 2016 CEST elapsed time: 32 seconds (0d 0h 0m 32s)

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

Current thread (0x00007fa7a03bb800): JavaThread "C2 CompilerThread0" daemon [_thread_in_vm, id=23761, stack(0x00007fa69b3fc000,0x00007fa69b4fd000)]


Current CompileTask:
C2: 32220 6923 ! 4 jdk.internal.reflect.GeneratedMethodAccessor355::invoke (286 bytes)

Stack: [0x00007fa69b3fc000,0x00007fa69b4fd000], sp=0x00007fa69b4f9290, free space=1012k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x146fa9e] VMError::report_and_die(int, char const*, char const*, __va_list_tag*, Thread*, unsigned char*, void*, void*, char const*, int, unsigned long)+0x47e
V [libjvm.so+0x14704ff] VMError::report_and_die(Thread*, char const*, int, char const*, char const*, __va_list_tag*)+0x2f
V [libjvm.so+0x950df0] report_vm_error(char const*, int, char const*, char const*, ...)+0xe0
V [libjvm.so+0x941107] ConstantPool::invoke_dynamic_name_and_type_ref_index_at(int)+0x37
V [libjvm.so+0x937e78] ConstantPool::impl_name_and_type_ref_index_at(int, bool)+0x138
V [libjvm.so+0x7e8308] ciBytecodeStream::get_method_signature_index()+0x498
V [libjvm.so+0x7e8a30] ciBytecodeStream::get_method(bool&, ciSignature**)+0x550
V [libjvm.so+0x7a7a43] ciMethod::get_method_at_bci(int, bool&, ciSignature**)+0x143
V [libjvm.so+0xa3ece9] Parse::do_call()+0x509
V [libjvm.so+0x11adae9] Parse::do_one_bytecode()+0x4f9
V [libjvm.so+0x11a1a4d] Parse::do_one_block()+0x40d
V [libjvm.so+0x11a214c] Parse::do_all_blocks()+0x21c
V [libjvm.so+0x11a3c75] Parse::Parse(JVMState*, ciMethod*, float)+0xba5
V [libjvm.so+0x7300c8] ParseGenerator::generate(JVMState*)+0x138
V [libjvm.so+0xa3ebc1] Parse::do_call()+0x3e1
V [libjvm.so+0x11adae9] Parse::do_one_bytecode()+0x4f9
V [libjvm.so+0x11a1a4d] Parse::do_one_block()+0x40d
V [libjvm.so+0x11a214c] Parse::do_all_blocks()+0x21c
V [libjvm.so+0x11a3c75] Parse::Parse(JVMState*, ciMethod*, float)+0xba5
V [libjvm.so+0x7300c8] ParseGenerator::generate(JVMState*)+0x138
V [libjvm.so+0x8d8369] Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int, bool, bool, bool, DirectiveSet*)+0xcd9
V [libjvm.so+0x72ea0b] C2Compiler::compile_method(ciEnv*, ciMethod*, int, DirectiveSet*)+0x2bb
V [libjvm.so+0x8e2661] CompileBroker::invoke_compiler_on_method(CompileTask*)+0x491
V [libjvm.so+0x8e331b] CompileBroker::compiler_thread_loop()+0x37b
V [libjvm.so+0x13df66e] JavaThread::thread_main_inner()+0x15e
V [libjvm.so+0x13df84d] JavaThread::run()+0x16d
V [libjvm.so+0x1151b12] java_start(Thread*)+0x112
C [libpthread.so.0+0x760a] start_thread+0xca