我和Tornado合作了很多，但这是我第一次遇到这种错误。我一直在研究一个非常基本的URL缩短器。 URL由不同的应用程序放入数据库，这只是从MongoDB商店读取URL并重定向客户端。在我编写基本代码之后，我设置了一个简单的'Siege'测试，在运行围攻大约30秒后（对{4个应用程序线程运行siege -c 64 -t 5m -r 1 http://example.com/MKy），我开始得到500个响应。查看错误日志，我看到了这一点;
ERROR:root:500 GET /MKy (127.0.0.1) 2.05ms
ERROR:root:Exception in I/O handler for fd 4
Traceback (most recent call last):
File "/opt/python2.7/lib/python2.7/site-packages/tornado-2.1-py2.7.egg/tornado/ioloop.py", line 309, in start
File "/opt/python2.7/lib/python2.7/site-packages/tornado-2.1-py2.7.egg/tornado/netutil.py", line 314, in accept_handler
File "/opt/python2.7/lib/python2.7/socket.py", line 200, in accept
error: [Errno 24] Too many open files
ERROR:root:Uncaught exception GET /MKy (127.0.0.1)
HTTPRequest(protocol='http', host='shortener', method='GET', uri='/MKy', version='HTTP/1.0', remote_ip='127.0.0.1', body='', headers={'Host': 'shortener', 'Accept-Encoding': 'gzip', 'X-Real-Ip': '94.23.155.32', 'X-Forwarded-For': '94.23.155.32', 'Connection': 'close', 'Accept': '*/*', 'User-Agent': 'JoeDog/1.00 [en] (X11; I; Siege 2.66)'})
Traceback (most recent call last):
File "/opt/python2.7/lib/python2.7/site-packages/tornado-2.1-py2.7.egg/tornado/web.py", line 1040, in wrapper
File "main.py", line 58, in get
File "main.py", line 21, in dbmongo
File "/opt/python2.7/lib/python2.7/site-packages/apymongo-0.0.1-py2.7-linux-x86_64.egg/apymongo/connection.py", line 349, in __init__
File "/opt/python2.7/lib/python2.7/site-packages/apymongo-0.0.1-py2.7-linux-x86_64.egg/apymongo/connection.py", line 510, in __find_master
File "/opt/python2.7/lib/python2.7/site-packages/apymongo-0.0.1-py2.7-linux-x86_64.egg/apymongo/connection.py", line 516, in __try_node
File "/opt/python2.7/lib/python2.7/site-packages/apymongo-0.0.1-py2.7-linux-x86_64.egg/apymongo/database.py", line 301, in command
File "/opt/python2.7/lib/python2.7/site-packages/apymongo-0.0.1-py2.7-linux-x86_64.egg/apymongo/collection.py", line 441, in find_one
File "/opt/python2.7/lib/python2.7/site-packages/apymongo-0.0.1-py2.7-linux-x86_64.egg/apymongo/cursor.py", line 539, in loop
File "/opt/python2.7/lib/python2.7/site-packages/apymongo-0.0.1-py2.7-linux-x86_64.egg/apymongo/cursor.py", line 560, in _refresh
File "/opt/python2.7/lib/python2.7/site-packages/apymongo-0.0.1-py2.7-linux-x86_64.egg/apymongo/cursor.py", line 620, in __send_message
File "/opt/python2.7/lib/python2.7/site-packages/apymongo-0.0.1-py2.7-linux-x86_64.egg/apymongo/connection.py", line 735, in _send_message_with_response
File "/opt/python2.7/lib/python2.7/site-packages/apymongo-0.0.1-py2.7-linux-x86_64.egg/apymongo/connection.py", line 591, in __stream
File "/opt/python2.7/lib/python2.7/site-packages/apymongo-0.0.1-py2.7-linux-x86_64.egg/apymongo/connection.py", line 200, in get_stream
File "/opt/python2.7/lib/python2.7/site-packages/apymongo-0.0.1-py2.7-linux-x86_64.egg/apymongo/connection.py", line 559, in __connect
AutoReconnect: could not connect to [('127.0.0.1', 27017)]
重要（我猜）;
错误：[Errno 24]打开文件太多
代码; （这很简单）
import tornado.ioloop
import tornado.web
import tornado.escape
import apymongo
import time
import sys
#Useful stuff (Connect to Mongo)
class setup(tornado.web.RequestHandler):
def dbmongo(self):
if not hasattr(self, '_dbmongo'):
self._dbmongo = apymongo.Connection("127.0.0.1", 27017)
return self._dbmongo
#Basic method to lookup URLs from Mongo and redirect accordingly
class expand(setup):
@tornado.web.asynchronous
def get(self, url):
self.mongo = self.dbmongo()
#Lookup the URL
cursor = self.mongo.rmgshortlinks.links.find_one({'short':url}, self.direct)
def direct(self, response):
if response == None:
self.send_error(404)
self.finish()
return
link = tornado.escape.url_unescape(response['long'])
#Bounce the client
self.write("<!DOCTYPE html><html><head><meta charset=\"UTF-8\" /><meta http-equiv=\"refresh\" content=\"0;URL="+link+"\"</head><body><a href=\""+link+"\">Click Here</a></body></html>")
self.finish();
#Define the URL routes
application = tornado.web.Application([
(r"/([a-zA-Z0-9]+)", expand)
])
#Start the server
if __name__ == "__main__":
listening_port = int(sys.argv[1])
if listening_port > 0:
application.listen(listening_port)
tornado.ioloop.IOLoop.instance().start()
else:
sys.stderr.write("No port specified!")
我正在使用的开发服务器有8个核心和64GB内存，运行RedHat Enterprise Linux 5和Python 2.6。我之前从未遇到过Tornado / Async Mongo应用程序的这些问题。
可能有用的信息;
[root@puma ~]# ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 31374
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 31374
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
（打开的文件只设置为1024，但我认为这已经足够了）
Tornado / Apymongo没有正确关闭连接吗？应用程序位于NGINX后面但使用HTTP连接，Apymongo应该通过TCP连接，但可能使用套接字。即便如此，它应该是共享/汇集连接不应该吗？
根据建议，将应用程序移动到我们的一个测试服务器上，最大打开文件限制为61440，在围攻中运行约30秒后出现相同的错误。
答案 0 :(得分：4)
很简单，RequestHandler对象是为每个请求实例化的。这意味着您要保存的缓存对象位于RequestHandler（例如，expand）对象上。
如果要向dbmongo（...）函数添加一个简单的“print'CREATED！'”，您会看到它是在每个GET请求上创建的。
您需要做的是将处理程序附加到类对象，或者根据需要附加“全局”，但最好的情况是将它放在Tornado Application对象上。
简单：
class setup(tornado.web.RequestHandler):
@classmethod
def dbmongo(cls):
if not hasattr(cls, '_dbmongo'):
cls._dbmongo = apymongo.Connection("127.0.0.1", 27017)
return cls._dbmongo
第二种方法只是让它成为你文件中的全局：
dbmongo_connection = None
def dbmongo():
if not dbmongo_connection:
dbmongo_connection = apymongo.Connection("127.0.0.1", 27017)
return dbmongo_connection
这两个问题都存在同样的问题，即如果你有很多想要使用数据库连接的类，那么分享它就更难了。由于数据库是一个共享实体，您可能需要一个用于整个应用程序的实体。
class MongoMixin(object):
def mongodb(self):
if not hasattr(self.application, 'mongodb'):
self.application.mongodb = apymongo.Connection(self.application.settings.get("mongohost", "127.0.0.1"), 27017)
return self.application.mongodb
class expand(tornado.web.RequestHandler, MongoMixin):
def get(self):
db = self.mongodb()