我有一个返回超时的 Sql Alchemy 应用程序:
TimeoutError:达到 QueuePool 大小 5 的限制溢出 10, 连接超时,超时30
我在另一篇文章中读到,当我不关闭会话时会发生这种情况,但我不知道这是否适用于我的代码:
我在init.py中连接数据库:
from .dbmodels import (
DBSession,
Base,
engine = create_engine("mysql://" + loadConfigVar("user") + ":" + loadConfigVar("password") + "@" + loadConfigVar("host") + "/" + loadConfigVar("schema"))
#Sets the engine to the session and the Base model class
DBSession.configure(bind=engine)
Base.metadata.bind = engine
然后在另一个 python 文件中,我在两个函数中收集一些数据,但使用我在 init.py 中初始化的 DBSession:
from .dbmodels import DBSession
from .dbmodels import resourcestatsModel
def getFeaturedGroups(max = 1):
try:
#Get the number of download per resource
transaction.commit()
rescount = DBSession.connection().execute("select resource_id,count(resource_id) as total FROM resourcestats")
#Move the data to an array
resources = []
data = {}
for row in rescount:
data["resource_id"] = row.resource_id
data["total"] = row.total
resources.append(data)
#Get the list of groups
group_list = toolkit.get_action('group_list')({}, {})
for group in group_list:
#Get the details of each group
group_info = toolkit.get_action('group_show')({}, {'id': group})
#Count the features of the group
addFesturedCount(resources,group,group_info)
#Order the FeaturedGroups by total
FeaturedGroups.sort(key=lambda x: x["total"],reverse=True)
print FeaturedGroups
#Move the data of the group to the result array.
result = []
count = 0
for group in FeaturedGroups:
group_info = toolkit.get_action('group_show')({}, {'id': group["group_id"]})
result.append(group_info)
count = count +1
if count == max:
break
return result
except:
return []
def getResourceStats(resourceID):
transaction.commit()
return DBSession.query(resourcestatsModel).filter_by(resource_id = resourceID).count()
会话变量的创建方式如下:
#Basic SQLAlchemy types
from sqlalchemy import (
Column,
Text,
DateTime,
Integer,
ForeignKey
)
# Use SQLAlchemy declarative type
from sqlalchemy.ext.declarative import declarative_base
#
from sqlalchemy.orm import (
scoped_session,
sessionmaker,
)
#Use Zope' sqlalchemy transaction manager
from zope.sqlalchemy import ZopeTransactionExtension
#Main plugin session
DBSession = scoped_session(sessionmaker(extension=ZopeTransactionExtension()))
因为会话是在 init.py 中创建的,在后续代码中我只是使用它;我什么时候需要关闭会话?或者我还需要做什么来管理池大小?
您可以通过在函数中添加参数 pool_size 和 max_overflow 来管理池大小
create_engine
engine = create_engine("mysql://" + loadConfigVar("user") + ":" + loadConfigVar("password") + "@" + loadConfigVar("host") + "/" + loadConfigVar("schema"),
pool_size=20, max_overflow=0)
参考是这里
您不需要关闭会话,但应在事务完成后关闭连接。 替换:
rescount = DBSession.connection().execute("select resource_id,count(resource_id) as total FROM resourcestats")
作者:
connection = DBSession.connection()
try:
rescount = connection.execute("select resource_id,count(resource_id) as total FROM resourcestats")
#do something
finally:
connection.close()
参考是这里
另外,请注意,mysql的过时连接会在特定时间段后关闭(这个时间段可以在MySQL中配置,我不记得默认值),所以你需要将pool_recycle值传递给你的引擎创建
将以下方法添加到您的代码中。它将自动关闭所有未使用/挂起的连接并防止代码出现瓶颈。特别是如果您使用以下语法 Model.query.filter_by(attribute=var).first() 和关系/延迟加载。
@app.teardown_appcontext
def shutdown_session(exception=None):
db.session.remove()
有关此内容的文档可在此处找到:http://flask.pocoo.org/docs/1.0/appcontext/
rescount = DBSession.connection().execute()
rescount
是 <class 'sqlalchemy.engine.cursor.CursorResult'>
类型。
您应该调用
close()
函数。