Python Flask Gevent 堆栈 - 简单的“Hello World”应用在基准测试中显示效率低下
我有一个简单的“你好，世界”应用：
from gevent import monkey
monkey.patch_all()
from flask import Flask
from gevent import wsgi
app = Flask(__name__)
@app.route('/')
def index():
return 'Hello World'
server = wsgi.WSGIServer(('127.0.0.1', 5000), app)
server.serve_forever()
如你所见，这个应用非常简单。
问题是，尽管它很简单，但运行起来却相当慢/效率低下，下面的基准测试（使用Apache Benchmark进行）显示了这一点：
ab -k -n 1000 -c 100 http://127.0.0.1:5000/
Benchmarking 127.0.0.1 (be patient)
Completed 100 requests
Completed 200 requests
Completed 300 requests
Completed 400 requests
Completed 500 requests
Completed 600 requests
Completed 700 requests
Completed 800 requests
Completed 900 requests
Completed 1000 requests
Finished 1000 requests
Server Software:
Server Hostname: 127.0.0.1
Server Port: 5000
Document Path: /
Document Length: 11 bytes
Concurrency Level: 100
Time taken for tests: 1.515 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Keep-Alive requests: 0
Total transferred: 146000 bytes
HTML transferred: 11000 bytes
Requests per second: 660.22 [#/sec] (mean)
Time per request: 151.465 [ms] (mean)
Time per request: 1.515 [ms] (mean, across all concurrent requests)
Transfer rate: 94.13 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.6 0 3
Processing: 1 145 33.5 149 191
Waiting: 1 144 33.5 148 191
Total: 4 145 33.0 149 191
Percentage of the requests served within a certain time (ms)
50% 149
66% 157
75% 165
80% 173
90% 183
95% 185
98% 187
99% 188
100% 191 (longest request)
即使增加连接数和/或并发数，结果也没有变好，实际上情况变得更糟。
我最担心的是，我的请求速度无法超过每秒700个请求，而传输速率也只有98 Kbytes/秒。
此外，单个请求的时间似乎也太长了。
我对Python和Gevent在后台做了什么感到好奇，或者更准确地说，操作系统在做什么，所以我使用了strace来查找可能的系统问题，结果如下：
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
56.46 0.000284 0 1386 close
24.25 0.000122 0 1016 write
10.74 0.000054 0 1000 send
4.17 0.000021 0 3652 3271 open
2.19 0.000011 0 641 read
2.19 0.000011 0 6006 fcntl64
0.00 0.000000 0 1 waitpid
0.00 0.000000 0 1 execve
0.00 0.000000 0 3 time
0.00 0.000000 0 12 12 access
0.00 0.000000 0 32 brk
0.00 0.000000 0 5 1 ioctl
0.00 0.000000 0 5006 gettimeofday
0.00 0.000000 0 4 2 readlink
0.00 0.000000 0 191 munmap
0.00 0.000000 0 1 1 statfs
0.00 0.000000 0 1 1 sigreturn
0.00 0.000000 0 2 clone
0.00 0.000000 0 2 uname
0.00 0.000000 0 21 mprotect
0.00 0.000000 0 69 65 _llseek
0.00 0.000000 0 71 rt_sigaction
0.00 0.000000 0 1 rt_sigprocmask
0.00 0.000000 0 3 getcwd
0.00 0.000000 0 1 getrlimit
0.00 0.000000 0 243 mmap2
0.00 0.000000 0 1838 748 stat64
0.00 0.000000 0 74 lstat64
0.00 0.000000 0 630 fstat64
0.00 0.000000 0 1 getuid32
0.00 0.000000 0 1 getgid32
0.00 0.000000 0 1 geteuid32
0.00 0.000000 0 1 getegid32
0.00 0.000000 0 4 getdents64
0.00 0.000000 0 3 1 futex
0.00 0.000000 0 1 set_thread_area
0.00 0.000000 0 2 epoll_ctl
0.00 0.000000 0 12 1 epoll_wait
0.00 0.000000 0 1 set_tid_address
0.00 0.000000 0 26 clock_gettime
0.00 0.000000 0 2 openat
0.00 0.000000 0 1 set_robust_list
0.00 0.000000 0 1 eventfd2
0.00 0.000000 0 1 epoll_create1
0.00 0.000000 0 1 pipe2
0.00 0.000000 0 1 socket
0.00 0.000000 0 1 bind
0.00 0.000000 0 1 listen
0.00 0.000000 0 1000 accept
0.00 0.000000 0 1 getsockname
0.00 0.000000 0 2000 1000 recv
0.00 0.000000 0 1 setsockopt
------ ----------- ----------- --------- --------- ----------------
100.00 0.000503 24977 5103 total
如你所见，有5103个错误，最严重的是open syscall，我怀疑这和找不到文件有关（ENOENT）。令我惊讶的是，epoll似乎并没有造成问题，尽管我听说过很多关于它的糟糕故事。
我想发布完整的strace，其中详细记录了每一个调用，但文件太大了。
最后一点；我还设置了以下系统参数（这是允许的最大值），希望能改善情况，但并没有：
echo “32768 61000″ > /proc/sys/net/ipv4/ip_local_port_range
sysctl -w fs.file-max=128000
sysctl -w net.ipv4.tcp_keepalive_time=300
sysctl -w net.core.somaxconn=61000
sysctl -w net.ipv4.tcp_max_syn_backlog=2500
sysctl -w net.core.netdev_max_backlog=2500
ulimit -n 1024
我的问题是，考虑到我使用的示例不能做太多修改来解决这些问题，我应该在哪里寻找解决方案呢？
更新 我用Wheezy.web和Gevent写了一个“你好，世界”脚本，结果达到了每秒约2000个请求：
from gevent import monkey
monkey.patch_all()
from gevent import pywsgi
from wheezy.http import HTTPResponse
from wheezy.http import WSGIApplication
from wheezy.routing import url
from wheezy.web.handlers import BaseHandler
from wheezy.web.middleware import bootstrap_defaults
from wheezy.web.middleware import path_routing_middleware_factory
def helloworld(request):
response = HTTPResponse()
response.write('hello world')
return response
routes = [
url('hello', helloworld, name='helloworld')
]
options = {}
main = WSGIApplication(
middleware=[
bootstrap_defaults(url_mapping=routes),
path_routing_middleware_factory
],
options=options
)
server = pywsgi.WSGIServer(('127.0.0.1', 5000), main, backlog=128000)
server.serve_forever()
基准测试结果如下：
ab -k -n 1000 -c 1000 http://127.0.0.1:5000/hello
Benchmarking 127.0.0.1 (be patient)
Completed 100 requests
Completed 200 requests
Completed 300 requests
Completed 400 requests
Completed 500 requests
Completed 600 requests
Completed 700 requests
Completed 800 requests
Completed 900 requests
Completed 1000 requests
Finished 1000 requests
Server Software:
Server Hostname: 127.0.0.1
Server Port: 5000
Document Path: /front
Document Length: 11 bytes
Concurrency Level: 1000
Time taken for tests: 0.484 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Keep-Alive requests: 0
Total transferred: 170000 bytes
HTML transferred: 11000 bytes
Requests per second: 2067.15 [#/sec] (mean)
Time per request: 483.758 [ms] (mean)
Time per request: 0.484 [ms] (mean, across all concurrent requests)
Transfer rate: 343.18 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 8 10.9 0 28
Processing: 2 78 39.7 56 263
Waiting: 2 78 39.7 56 263
Total: 18 86 42.6 66 263
Percentage of the requests served within a certain time (ms)
50% 66
66% 83
75% 129
80% 131
90% 152
95% 160
98% 178
99% 182
100% 263 (longest request)
我觉得Wheezy.web的速度很不错，但我还是想用Flask，因为它更简单，工作起来也不那么费时间。
1 个回答
1
你在用哪个版本的gevent？试着把你的软件环境简化到最基本的部分，然后试试他们在github上提供的示例。
https://github.com/gevent/gevent/blob/master/examples/wsgiserver.py
你是在把你的测试结果和非-gevent版本进行比较吗？我一直觉得这个库能大幅提升速度，所以我建议你再深入调查一下。