C libcurl，限制下载速度-cpu使用率达到100%

我对CURLOPT_MAX_RECV_SPEED_LARGE api手册页有问题。

我想设置最大下载速度，所以我添加了：

curl_off_t max_speed = 1000*25;
curl_easy_setopt(curl_handle, CURLOPT_MAX_RECV_SPEED_LARGE, max_speed);

但问题是，当它达到极限（25kB/s）或我设置的速度时，CPU使用率会达到100%

我用错方法了吗我想，因为我在任何地方都没有发现这个问题。我试图将这两行代码添加到原始示例代码中，但它也变得疯狂。

我使用的是Windows和libcurl v 7.29

感谢

可能的解决方案是编写自己的睡眠进行中函数，但是

这是原始代码"getimemory.c"，添加了2行：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
struct MemoryStruct {
  char *memory;
  size_t size;
};

static size_t WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void     *userp)
{
  size_t realsize = size * nmemb;
  struct MemoryStruct *mem = (struct MemoryStruct *)userp;
  mem->memory =(char*) realloc(mem->memory, mem->size + realsize + 1);
  if(mem->memory == NULL) {
    /* out of memory! */
    printf("not enough memory (realloc returned NULL)n");
    return 0;
  }
  memcpy(&(mem->memory[mem->size]), contents, realsize);
  mem->size += realsize;
  mem->memory[mem->size] = 0;
  return realsize;
}

int main(void)
{
  CURL *curl_handle;
  CURLcode res;
  struct MemoryStruct chunk;
  chunk.memory = (char*)malloc(1);  /* will be grown as needed by the realloc     above */
  chunk.size = 0;    /* no data at this point */
  curl_global_init(CURL_GLOBAL_ALL);
  curl_handle = curl_easy_init();
  curl_easy_setopt(curl_handle, CURLOPT_URL,     "http://ns223506.ovh.net/rozne/04e4383e647ce87ce42e73fa00bb0058/wallpaper-812988.jpg");   //Random wallpaper
  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
  curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);
  curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0");
  //My added 2 lines
  curl_off_t max_speed = 1000*25; // 25kB/s
  curl_easy_setopt(curl_handle, CURLOPT_MAX_RECV_SPEED_LARGE, max_speed);

  res = curl_easy_perform(curl_handle);
  if(res != CURLE_OK) {
    fprintf(stderr, "curl_easy_perform() failed: %sn",
            curl_easy_strerror(res));
  }
  else {
    printf("%lu bytes retrievedn", (long)chunk.size);
  }
  curl_easy_cleanup(curl_handle);
  if(chunk.memory)
    free(chunk.memory);
   curl_global_cleanup();
  return 0;
}