I use ab(apache bench) to test my web,but error "apr_socket_connect(): Connection reset by peer (54)" on macOS

code is ab -n 10000 -c 20 http://127.0.0.1:8000/meiduo_admin/statistical/total_count/,but error. error infomation is

Benchmarking 127.0.0.1 (be patient)
Completed 1000 requests
Send request failed!
Completed 2000 requests
Send request failed!
Send request failed!
Completed 3000 requests
Send request failed!
Send request failed!
Send request failed!

Test aborted after 10 failures

apr_socket_connect(): Connection reset by peer (54)
Total of 3965 requests completed

why occur this? I guess concurrence num is too hight.