mpi，即使处理器可用，也无法分配插槽

Question

我正在以下linux计算机资源上运行一个mpi程序：

CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                32
On-line CPU(s) list:   0-31
Thread(s) per core:    2
Core(s) per socket:    8

当我使用以下方法生成进程时会发生问题：

    MPI_Comm_spawn("./processes/montecarlo", array_of_argv, numworkers,
            MPI_INFO_NULL,
            0, MPI_COMM_SELF, &workercomm, MPI_ERRCODES_IGNORE);

numworkers，如果我将其设置为30（因为我有32个CPU）或什至设置为20或15 ==>我将收到以下消息：

   There are not enough slots available in the system to satisfy the 21 slots
   that were requested by the application:
   ./processes/montecarlo

    Either request fewer slots for your application, or make more slots 
    available for use.