os::initialize_thread()

• カレントスレッドを初期化する
• Linux版、Windows版では実装されていない

//Linux版(jdk7/hotspot/src/os_cpu/linux_x86/vm/os_linux_x86.cpp)
void os::initialize_thread() {
// Nothing to do.
}

ちなみにSolaris版はこんな感じ。

//Solaris版(jdk7/hotspot/src/os/solaris/vm/os_solaris.cpp)
// First crack at OS-specific initialization, from inside the new thread.
void os::initialize_thread() {
  int r = thr_main() ;
  guarantee (r == 0 || r == 1, "CR6501650 or CR6493689") ;
  if (r) {
    JavaThread* jt = (JavaThread *)Thread::current();
    assert(jt != NULL,"Sanity check");
    size_t stack_size;
    address base = jt->stack_base();
    if (Arguments::created_by_java_launcher()) {
      // Use 2MB to allow for Solaris 7 64 bit mode.
      stack_size = JavaThread::stack_size_at_create() == 0
        ? 2048*K : JavaThread::stack_size_at_create();

      // There are rare cases when we may have already used more than
      // the basic stack size allotment before this method is invoked.
      // Attempt to allow for a normally sized java_stack.
      size_t current_stack_offset = (size_t)(base - (address)&stack_size);
      stack_size += ReservedSpace::page_align_size_down(current_stack_offset);
    } else {
      // 6269555: If we were not created by a Java launcher, i.e. if we are
      // running embedded in a native application, treat the primordial thread
      // as much like a native attached thread as possible.  This means using
      // the current stack size from thr_stksegment(), unless it is too large
      // to reliably setup guard pages.  A reasonable max size is 8MB.
      size_t current_size = current_stack_size();
      // This should never happen, but just in case....
      if (current_size == 0) current_size = 2 * K * K;
      stack_size = current_size > (8 * K * K) ? (8 * K * K) : current_size;
    }
    address bottom = (address)align_size_up((intptr_t)(base - stack_size), os::vm_page_size());;
    stack_size = (size_t)(base - bottom);

    assert(stack_size > 0, "Stack size calculation problem");

    if (stack_size > jt->stack_size()) {
      NOT_PRODUCT(
        struct rlimit limits;
        getrlimit(RLIMIT_STACK, &limits);
        size_t size = adjust_stack_size(base, (size_t)limits.rlim_cur);
        assert(size >= jt->stack_size(), "Stack size problem in main thread");
      )
      tty->print_cr(
        "Stack size of %d Kb exceeds current limit of %d Kb.\n"
        "(Stack sizes are rounded up to a multiple of the system page size.)\n"
        "See limit(1) to increase the stack size limit.",
        stack_size / K, jt->stack_size() / K);
      vm_exit(1);
    }
    assert(jt->stack_size() >= stack_size,
          "Attempt to map more stack than was allocated");
    jt->set_stack_size(stack_size);
  }

   // 5/22/01: Right now alternate signal stacks do not handle
   // throwing stack overflow exceptions, see bug 4463178
   // Until a fix is found for this, T2 will NOT imply alternate signal
   // stacks.
   // If using T2 libthread threads, install an alternate signal stack.
   // Because alternate stacks associate with LWPs on Solaris,
   // see sigaltstack(2), if using UNBOUND threads, or if UseBoundThreads
   // we prefer to explicitly stack bang.
   // If not using T2 libthread, but using UseBoundThreads any threads
   // (primordial thread, jni_attachCurrentThread) we do not create,
   // probably are not bound, therefore they can not have an alternate
   // signal stack. Since our stack banging code is generated and
   // is shared across threads, all threads must be bound to allow
   // using alternate signal stacks.  The alternative is to interpose
   // on _lwp_create to associate an alt sig stack with each LWP,
   // and this could be a problem when the JVM is embedded.
   // We would prefer to use alternate signal stacks with T2
   // Since there is currently no accurate way to detect T2
   // we do not. Assuming T2 when running T1 causes sig 11s or assertions
   // on installing alternate signal stacks


   // 05/09/03: removed alternate signal stack support for Solaris
   // The alternate signal stack mechanism is no longer needed to
   // handle stack overflow. This is now handled by allocating
   // guard pages (red zone) and stackbanging.
   // Initially the alternate signal stack mechanism was removed because
   // it did not work with T1 llibthread. Alternate
   // signal stacks MUST have all threads bound to lwps. Applications
   // can create their own threads and attach them without their being
   // bound under T1. This is frequently the case for the primordial thread.
   // If we were ever to reenable this mechanism we would need to
   // use the dynamic check for T2 libthread.

  os::Solaris::init_thread_fpu_state();
  std::set_terminate(_handle_uncaught_cxx_exception);
}