Decorator like this
engine = create_engine(
'mssql+pymssql://{LOGIN}:{PASSWORD}@{HOST}/{DATABASE}?charset={CHARSET}&timeout={TIMEOUT}'.format(**DATABASE),
isolation_level='READ COMMITTED'
)
def decorator_with_args(decorator_to_enhance):
"""
https://habrahabr.ru/post/141501/
"""
def decorator_maker(*args, **kwargs):
def decorator_wrapper(func):
return decorator_to_enhance(func, *args, **kwargs)
return decorator_wrapper
return decorator_maker
def scope_func():
return scoped_session(sessionmaker(bind=engine, autocommit=True))()
@decorator_with_args
def session_decorator(func, default=None, **kwargs):
def wrapper(*a, **kw):
session = scope_func()
if 'session' not in kw:
kw['session'] = session
try:
return func(*a, **kw)
except Exception as e:
session.rollback()
print('#####FUNCTION NAME: {}'.format(func.__name__))
print(e)
logging.error(e)
return default
return wrapper
среда, 14 февраля 2018 г., 17:06:54 UTC+3 пользователь Simon King написал:
>
> The pattern you should be aiming for is one in which a fresh
> transaction is started for every web request that touches the
> database, and that the transaction is closed at the end of the
> request. How are you ensuring that at the moment?
>
> Simon
>
> On Wed, Feb 14, 2018 at 12:51 PM, <eugene...@gmail.com <javascript:>>
> wrote:
> > If I run tests where all functions run one-by-one - all tests passed.
> > But when i run web app and functions can call almost in parallel then i
> have
> > a problem, then there are problems - transactions can block each other.
> > I tried to set the isolation level of SNAPSHOT and READ COMMITTED, but
> it
> > did not help.
> >
> > среда, 14 февраля 2018 г., 14:58:37 UTC+3 пользователь
> eugene...@gmail.com
> > написал:
> >>
> >> Hello, Mike!
> >> In my web app i have many selects like
> >> session.execute(select([table1]).where(condition))
> >> and not so much updates, inserts and deletes like
> >> session.execute(update(table1).where(condition).values(**values))
> >> session.execute(insert(table1).values(**values))
> >> session.execute(delete(table1).where(condition))
> >>
> >> What better way to create session for web application?
> >> Without additional components like flask-sqlalchemy.
> >>
> >> суббота, 27 января 2018 г., 20:23:05 UTC+3 пользователь Mike Bayer
> >> написал:
> >>>
> >>> On Sat, Jan 27, 2018 at 5:49 AM, Евгений Рымарев
> >>> <rymarev...@gmail.com> wrote:
> >>> > I receive this error:
> >>> > This result object does not return rows. It has been closed
> >>> > automatically.
> >>>
> >>> there's a lot of weird situations which can cause that error, usually
> >>> when using a connection that has had some failure condition occur upon
> >>> it which renders the connection unusable until either a transaction is
> >>> rolled back or sometimes the connection needs to be discarded. We
> >>> can't diagnose it without a full example that reproduces it as well as
> >>> the complete stack trace.
> >>>
> >>>
> >>> >
> >>> >
> >>> >
> >>> > суббота, 27 января 2018 г., 1:09:53 UTC+3 пользователь Mike Bayer
> >>> > написал:
> >>> >>
> >>> >> On Fri, Jan 26, 2018 at 4:21 PM, Евгений Рымарев
> >>> >> <rymarev...@gmail.com> wrote:
> >>> >> > Hello, everyone!
> >>> >> > Engine:
> >>> >> > engine = create_engine(
> >>> >> >
> >>> >> >
> >>> >> >
> >>> >> >
> 'mssql+pymssql://{LOGIN}:{PASSWORD}@{HOST}/{DATABASE}?charset={CHARSET}'.format(**DATABASE),
>
>
> >>> >> > isolation_level='READ COMMITTED'
> >>> >> > )
> >>> >> >
> >>> >> >
> >>> >> > My first decorator for session:
> >>> >> > @decorator_with_args
> >>> >> > def session_decorator(func, default=None):
> >>> >> > def wrapper(*a, **kw):
> >>> >> > s = Session(engine)
> >>> >> > kw['session'] = s
> >>> >> > try:
> >>> >> > return func(*a, **kw)
> >>> >> > except Exception as e:
> >>> >> > func(*a, **kw)
> >>> >> > s.rollback()
> >>> >> > s.close()
> >>> >> > logging.error(e)
> >>> >> > return default
> >>> >> > finally:
> >>> >> > s.commit()
> >>> >> > s.close()
> >>> >> > return wrapper
> >>> >> >
> >>> >> > My second decorator for session:
> >>> >> > session = scoped_session(sessionmaker(bind=engine))
> >>> >> >
> >>> >> >
> >>> >> > @decorator_with_args
> >>> >> > def session_decorator(func, default=None):
> >>> >> > def wrapper(*a, **kw):
> >>> >> > kw['session'] = session
> >>> >> > try:
> >>> >> > return func(*a, **kw)
> >>> >> > except Exception as e:
> >>> >> > session.remove()
> >>> >> > logging.error(e)
> >>> >> > return default
> >>> >> > finally:
> >>> >> > session.remove()
> >>> >> > return wrapper
> >>> >> >
> >>> >> > In both attempts, I came to the conclusion that sessions can
> block
> >>> >> > other
> >>> >> > sessions.
> >>> >> > How correctly to create a session once, so that it can be used
> >>> >> > throughout
> >>> >> > the web application and no locks were created?
> >>> >>
> >>> >> The Session doesn't create locks, transactions and your database
> does.
> >>> >>
> >>> >> What is the nature of these "blocks", are they deadlocks between
> >>> >> tables or rows? What operations are prevented from proceeding?
> Are
> >>> >> the locks timing out? SQL Server has graphical consoles that can
> >>> >> show you this.
> >>> >>
> >>> >> What version of SQL Server is this? Do you have
> >>> >> ALLOW_SNAPSHOT_ISOLATION and READ_COMMITTED_SNAPSHOT turned on?
> >>> >>
> >>> >>
> >>> >> >
> >>> >> > --
> >>> >> > SQLAlchemy -
> >>> >> > The Python SQL Toolkit and Object Relational Mapper
> >>> >> >
> >>> >> > http://www.sqlalchemy.org/
> >>> >> >
> >>> >> > To post example code, please provide an MCVE: Minimal, Complete,
> and
> >>> >> > Verifiable Example. See http://stackoverflow.com/help/mcve for a
> >>> >> > full
> >>> >> > description.
> >>> >> > ---
> >>> >> > You received this message because you are subscribed to the
> Google
> >>> >> > Groups
> >>> >> > "sqlalchemy" group.
> >>> >> > To unsubscribe from this group and stop receiving emails from it,
> >>> >> > send
> >>> >> > an
> >>> >> > email to sqlalchemy+...@googlegroups.com.
> >>> >> > To post to this group, send email to sqlal...@googlegroups.com.
> >>> >> > Visit this group at https://groups.google.com/group/sqlalchemy.
> >>> >> > For more options, visit https://groups.google.com/d/optout.
> >>> >
> >>> > --
> >>> > SQLAlchemy -
> >>> > The Python SQL Toolkit and Object Relational Mapper
> >>> >
> >>> > http://www.sqlalchemy.org/
> >>> >
> >>> > To post example code, please provide an MCVE: Minimal, Complete, and
> >>> > Verifiable Example. See http://stackoverflow.com/help/mcve for a
> full
> >>> > description.
> >>> > ---
> >>> > You received this message because you are subscribed to the Google
> >>> > Groups
> >>> > "sqlalchemy" group.
> >>> > To unsubscribe from this group and stop receiving emails from it,
> send
> >>> > an
> >>> > email to sqlalchemy+...@googlegroups.com.
> >>> > To post to this group, send email to sqlal...@googlegroups.com.
> >>> > Visit this group at https://groups.google.com/group/sqlalchemy.
> >>> > For more options, visit https://groups.google.com/d/optout.
> >
> > --
> > SQLAlchemy -
> > The Python SQL Toolkit and Object Relational Mapper
> >
> > http://www.sqlalchemy.org/
> >
> > To post example code, please provide an MCVE: Minimal, Complete, and
> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> > description.
> > ---
> > You received this message because you are subscribed to the Google
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> > "sqlalchemy" group.
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> an
> > email to sqlalchemy+...@googlegroups.com <javascript:>.
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> <javascript:>.
> > Visit this group at https://groups.google.com/group/sqlalchemy.
> > For more options, visit https://groups.google.com/d/optout.
>
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
---
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