Sent log data to logstash, log loss occurred?

Use UDP to send the log data sent to logstash, about 10 requests per second, each sending a thousand probably only received 400-600, strange, Udp in the LAN, the concurrency is not high, how to lose the log It?

```
local logger = require "resty.logger.socket"
local json = require "cjson"

if not logger then
ngx.log(ngx.ERR, "can't required logger module")
end
if not logger.initted() then
local ok, err = logger.init{
host = '10.105.7.43',
port = 5000,
sock_type = 'udp',
flush_limit = 1,
drop_limit = 5678,
}
if not ok then
ngx.log(ngx.ERR, "failed to initialize the logger: ",
err)
end
end

local log = {}

local client = ngx.var.http_x_forwarded_for
local url = ngx.var.uri
local x_auth_token = ngx.req.get_headers()['X-AUTH-TOKEN']
local method = ngx.var.request_method

log['client'] = client
log['url'] = url
log['method'] = method
log['X-AUTH-TOKEN'] = x_auth_token

local bytes, err = logger.log(json.encode(log))
if bytes then
ngx.log(ngx.INFO, "send done")
end
if err then
ngx.log(ngx.ERR, "failed to log message: ", err)
end