龙卷风+ momoko不处理连接

Question

我使用tornado(4.2.1)+ momoko(2.2.0)+ psycopg2(2.6.1)进行小型Web应用程序,它可以正常运行,直到PostgreSQL服务器关闭连接.然后在每个db.execute()命令后,我收到一条错误消息:

Traceback (most recent call last):
      File "C:\Python27\lib\site-packages\tornado-4.2.1-py2.7-win32.egg\tornado\web.py", line 1415, in _execute
        result = yield result
      File "C:\Python27\lib\site-packages\tornado-4.2.1-py2.7-win32.egg\tornado\gen.py", line 870, in run
        value = future.result()
      File "C:\Python27\lib\site-packages\tornado-4.2.1-py2.7-win32.egg\tornado\concurrent.py", line 215, in result
        raise_exc_info(self._exc_info)
      File "C:\Python27\lib\site-packages\tornado-4.2.1-py2.7-win32.egg\tornado\gen.py", line 876, in run
        yielded = self.gen.throw(*exc_info)
      File "server.py", line 63, in get
        cursor = yield self.db.execute(query)
      File "C:\Python27\lib\site-packages\tornado-4.2.1-py2.7-win32.egg\tornado\gen.py", line 870, in run
        value = future.result()
      File "C:\Python27\lib\site-packages\tornado-4.2.1-py2.7-win32.egg\tornado\concurrent.py", line 215, in result
        raise_exc_info(self._exc_info)
      File "D:\work\program-stat\momoko\connection.py", line 453, in when_available
        future_or_result = method(conn, *args, **kwargs)
      File "D:\work\program-stat\momoko\connection.py", line 743, in execute
        cursor.execute(operation, parameters)
      File "C:\Python27\lib\site-packages\psycopg2\extras.py", line 288, in execute
        return super(NamedTupleCursor, self).execute(query, vars)
    OperationalError: server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.

这是一个代码:

import os
import tornado.httpserver
import tornado.ioloop
import tornado.options
import tornado.web
import momoko

from tornadotools.route import Route
from psycopg2.extras import NamedTupleCursor

import environments as env


tornado.options.define("port", default=9999, help="run on the given port", type=int)
tornado.options.define("pgsql_host", default=env.DB_HOST, help="database host")
tornado.options.define("pgsql_database", default=env.DB_DATABASE, help="database name")
tornado.options.define("pgsql_user", default=env.DB_LOGIN, help="database user")
tornado.options.define("pgsql_password", default=env.DB_PASSWORD, help="database password")


class Application(tornado.web.Application):
    def __init__(self):
        handlers = Route.routes()
        settings = dict(
            template_path=os.path.join(os.path.dirname(__file__), "templates"),
            static_path=os.path.join(os.path.dirname(__file__), "static"),
            debug=True,
        )
        tornado.web.Application.__init__(self, handlers, **settings)

        # Have one global connection to DB across all handlers
        self.db = momoko.Pool(
            dsn='dbname=%s user=%s password=%s '
                'host=%s port=5432' % (
                    tornado.options.options.pgsql_database,
                    tornado.options.options.pgsql_user,
                    tornado.options.options.pgsql_password,
                    tornado.options.options.pgsql_host),
            cursor_factory=NamedTupleCursor,
        )
        self.db.connect()


class BaseHandler(tornado.web.RequestHandler):
    @property
    def db(self):
        return self.application.db

@Route(r"/")
class HomeHandler(BaseHandler):
    def get(self):
        self.write("<ul>")
        self.write("<li><a href='/test'>Test page</a>")
        self.write("</ul>")
        self.finish()

@Route(r"/test")
class MogrifyHandler(BaseHandler):

    @tornado.web.asynchronous
    @tornado.gen.coroutine
    def get(self):
        cursor = yield self.db.execute("SELECT %s as t;", (1,))
        self.render("test.html", result=cursor.fetchall())


def main():
    tornado.options.parse_command_line()
    http_server = tornado.httpserver.HTTPServer(Application())
    http_server.listen(tornado.options.options.port)
    tornado.ioloop.IOLoop.instance().start()


if __name__ == "__main__":
    main()

如何在不重新启动应用程序的情况下自动处理此异常并重新连接到数据库？

Answer 1

您可以添加参数：

raise_connect_errors=False,

创建连接池时：

self.db = momoko.Pool(
    dsn='dbname=%s user=%s password=%s '
        'host=%s port=5432' % (
            tornado.options.options.pgsql_database,
            tornado.options.options.pgsql_user,
            tornado.options.options.pgsql_password,
            tornado.options.options.pgsql_host),
    cursor_factory=NamedTupleCursor,
    raise_connect_errors=False,
)

但这并不总是有帮助。