no response when I used wrk to test the server based on cpprest

[winstard]

I changed the source code of CasaLens(the sample project) like this:

 void CasaLens::handle_get(http_request message)
{    
	static std::mutex mutex;
	message.reply(web::http::status_codes::OK);
	std::lock_guard<std::mutex>` `lock(mutex);
	static int b = 0;
	std::wcout << "b " << b++ << std::endl;
	return;
}

Then I used wrk to test the performance
wrk -c 1500 -t 10 -d 1m --timeout=30s http://10.22.99.13:12344

the result was:

Running 1m test @ http://10.22.99.13:12344
  10 threads and 1500 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     1.24s   284.07ms   1.42s    86.96%
    Req/Sec    13.17     14.51    42.00     83.33%
  23 requests in 1.00m, 2.38KB read
  Socket errors: connect 489, read 169, write 0, timeout 0
Requests/sec:      0.38
Transfer/sec:      40.57B

It just printed

b 1
b 2
...
b 1033

on the consle of the CasaLens.
And there was no response when I hit Enter in the consle.

I tried to debug the cpprest. Found that it can't callback after called HttpReceiveHttpRequest at void windows_request_context::async_process_request(HTTP_REQUEST_ID request_id, http_request msg, const unsigned long headers_size),when wrk has been executed for a while.
And no response after listener.close().wait();

The same question when I try to use cpprest to create a restful service on Linux.
Is my usage or something else wrong?