In several places in hotspot, we call CompileBroker::log_metaspace_failure(). I believe the intent is to call it from compiler threads only, because it ends up calling:

  void log_metaspace_failure(const char* reason) {
    ResourceMark rm;
    StringLogMessage lm;
    lm.print("%4d COMPILE PROFILING SKIPPED: %s", -1, reason);
    lm.print("\n");
    log(JavaThread::current(), "%s", (const char*)lm);
  }

...which would fail the cast in `JavaThread::current()` if current thread is not Java thread (compiler threads are Java threads too).

It clearly manifests on JDK-8282170 test:

12700 breakpoints set
12800 breakpoints set
12900 breakpoints set
13000 breakpoints set
# To suppress the following error report, specify this argument
# after -XX: or in .hotspotrc: SuppressErrorAt=/thread.hpp:1458
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/home/shade/trunks/jdk/src/hotspot/share/runtime/thread.hpp:1458), pid=889379, tid=889389
# assert(t->is_Java_thread()) failed: incorrect cast to JavaThread


Current thread (0x00007f696c20ba30): VMThread "VM Thread" [stack: 0x00007f694f5a5000,0x00007f694f6a5000] [id=889389]

Stack: [0x00007f694f5a5000,0x00007f694f6a5000], sp=0x00007f694f6a3510, free space=1017k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0xacfad4] CompilationLog::log_metaspace_failure(char const*)+0x494
V [libjvm.so+0xac84b0] CompileBroker::log_metaspace_failure()+0x20
V [libjvm.so+0x15069e9] Method::build_method_counters(Thread*, Method*)+0x119
V [libjvm.so+0x150851b] BreakpointInfo::set(Method*)+0xfb
V [libjvm.so+0x127d5ea] JvmtiBreakpoint::each_method_version_do(void (Method::*)(int))+0x5a
V [libjvm.so+0x1b342ae] VM_Operation::evaluate()+0x18e
V [libjvm.so+0x1b581f7] VMThread::evaluate_operation(VM_Operation*)+0x1f7
V [libjvm.so+0x1b5925f] VMThread::inner_execute(VM_Operation*)+0x41f
V [libjvm.so+0x1b59425] VMThread::loop()+0xb5
V [libjvm.so+0x1b59548] VMThread::run()+0xb8
V [libjvm.so+0x1a450d4] Thread::call_run()+0x104
V [libjvm.so+0x161b3fc] thread_native_entry(Thread*)+0x10c