Golang Server Timeout

Question

I have a very simple go server:

package main

import(
  "net/http"
  "fmt"
  "log"
)

func test(w http.ResponseWriter, r *http.Request){
  fmt.Println("No bid")
  http.Error(w, "NoBid", 204)
}

func main() {
  http.HandleFunc("/test/bid", test)
  http.ListenAndServe(":8080", nil)
  log.Println("Done serving")
}

I then run the apache benchmark tool:

ab -c 50 -n 50000 -p post.txt http://127.0.0.1:8080/test/bid

The Server runs and responds to about 15000 requests and then times out. I was wondering why this happens and if there is something I can do about this.

try running your executable in the following way: nohup ./[name] — ymg
– ymg, Commented Dec 12, 2013 at 23:19
What error are you getting (if any?). Chances are you are starved of open sockets on your operating system. I'd also recommend using wrk (github.com/wg/wrk) or weighttp (github.com/lighttpd/weighttp) instead of Apache Bench. — elithrar
– elithrar, Commented Dec 12, 2013 at 23:22
Thank you for the feedback, I could not get nohup or r.Body.Close to alleviate my problem. I will check out the other benchmarking tools and see if I can find anything. — Gary
– Gary, Commented Dec 12, 2013 at 23:39
I started to use wrk and I think it is better for what I am doing, thank you much — Gary
– Gary, Commented Dec 13, 2013 at 0:08

Specode · Accepted Answer · 2013-12-13 02:13:31Z

3

If you running in Linux, Maybe too many open files, so it can't create connection, You need change system config to support more connections.

For example,

edit /etc/security/limits.conf add

*    soft    nofile 100000
*    soft    nofile 100000

To open more file.

edit /etc/sysctl.conf

# use more port
net.ipv4.ip_local_port_range = 1024 65000
# keep alive timeout
net.ipv4.tcp_keepalive_time = 300
# allow reuse
net.ipv4.tcp_tw_reuse = 1
# quick recovery
net.ipv4.tcp_tw_recycle = 1

answered Dec 13, 2013 at 2:13

Specode

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Comments

Nick Craig-Wood · Accepted Answer · 2013-12-13 00:29:03Z

I tried to replicate your problem on my linux amd64 laptop with no success - it worked fine even with

ab -c 200 -n 500000 -p post.txt http://127.0.0.1:8080/test/bid

There were about 28,000 sockets open though which may be bumping a limit on your system.

A more real world test might be to turn keepalives on which maxes out at 400 sockets

ab -k -c 200 -n 500000 -p post.txt http://127.0.0.1:8080/test/bid

The result for this was

Server Software:        
Server Hostname:        127.0.0.1
Server Port:            8080

Document Path:          /test/bid
Document Length:        6 bytes

Concurrency Level:      200
Time taken for tests:   33.807 seconds
Complete requests:      500000
Failed requests:        0
Write errors:           0
Keep-Alive requests:    500000
Total transferred:      77000000 bytes
Total body sent:        221500000
HTML transferred:       3000000 bytes
Requests per second:    14790.04 [#/sec] (mean)
Time per request:       13.523 [ms] (mean)
Time per request:       0.068 [ms] (mean, across all concurrent requests)
Transfer rate:          2224.28 [Kbytes/sec] received
                        6398.43 kb/s sent
                        8622.71 kb/s total

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.1      0      11
Processing:     0   14   5.2     13      42
Waiting:        0   14   5.2     13      42
Total:          0   14   5.2     13      42

Percentage of the requests served within a certain time (ms)
  50%     13
  66%     16
  75%     17
  80%     18
  90%     20
  95%     21
  98%     24
  99%     27
 100%     42 (longest request)

I suggest you try ab with -k and take a look at tuning your system for lots of open sockets

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