To help diagnosing os::create_thread failures, in the following block of code, all information should be printed at the "warning" level.

https://github.com/openjdk/jdk/blob/0d2f87e49401cc97ee095a836f4ca19741730b4f/src/hotspot/os/windows/os_windows.cpp#L771

    log_warning(os, thread)("Failed to start thread - _beginthreadex failed (%s) for attributes: %s.",
      os::errno_name(errno), describe_beginthreadex_attributes(buf, sizeof(buf), stack_size, initflag));
    // Log some OS information which might explain why creating the thread failed.
    log_info(os, thread)("Number of threads approx. running in the VM: %d", Threads::number_of_threads());
    LogStream st(Log(os, thread)::info());
    os::print_memory_info(&st);

Such failures are rare, and usually people won't be running with -Xlog:thread, so the messages aren't available when they are needed the most.