How to handle lock on database row when using tornado? - Tornado Web Server

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Message from discussion How to handle lock on database row when using tornado?
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Date: Thu, 11 Oct 2012 17:28:51 +0300
Message-ID: <CAJZrG8hegi0-A2XTGxrq=d2iVofk_ohKOc3eMFWfRDJ_vwT...@mail.gmail.com>
Subject: Re: [tornado] How to handle lock on database row when using tornado?
From: "Serge S. Koval" <serge.ko...@gmail.com>
To: python-tornado@googlegroups.com
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Hi,

 Did you try https://github.com/FSX/momoko? Or you want to use ORM?

 As far as I know, there are no asynchronous ORMs with Tornado support. So,
it is either background thread with a queue, which can use blocking ORM or
raw SQL through asynchronous driver.

Serge.

On Thu, Oct 11, 2012 at 4:36 PM, Jimmy <li.jiam...@gmail.com> wrote:

> My application has a need to lock a row in database for update. But when
> another request comes to hit the same row, the query will be pending until
> the previous lock is release. But this will hold all requests in the same
> thread.
>
> I have searched for several ways of get around of this issue. Not sure
> which is the best way to handle it. I would like to hear your experience
> about this issue. My potential solutions:
> 1. move the locked query to backend job. and return the response when the
> job finished.
>     pro: clean and follow async manner of tornado
>     con: it may keep the connect open for longer time
> 2. Use async db library to load.
>     pro: fast and follow async manner
>     con: few async db library supports sqlalchemy for orm, which is
> important to us. I have tried twisted adbapi, and adb with MySQL. but the
> experience is not good (Maybe because I'm new to twisted). gevent with
> psycopg2 works with sqlalchemy, but I can't enjoy the async support from
> tornado (I can only use gevent.spawn and join for async, and tornado is
> only for wsgi application).
> 3. Set short timeout to each query. (This is the last thing I want to do)
>     pro: easy and simple
>     con: Bad user experience bcz of timeout.
>
> I would like to know if there is a general solution for issue like this.
>
> Thank you.
>

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Hi,<div><br></div><div>=A0Did you try=A0<a href=3D"https://github.com/FSX/m=
omoko">https://github.com/FSX/momoko</a>? Or you want to use ORM?</div><div=
><br></div><div>=A0As far as I know, there are no asynchronous ORMs with To=
rnado support. So, it is either background thread with a queue, which can u=
se blocking ORM or raw SQL through asynchronous driver.</div>
<div><br></div><div>Serge.<br><br><div class=3D"gmail_quote">On Thu, Oct 11=
, 2012 at 4:36 PM, Jimmy <span dir=3D"ltr">&lt;<a href=3D"mailto:li.jiaming=
@gmail.com" target=3D"_blank">li.jiam...@gmail.com</a>&gt;</span> wrote:<br=
><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1=
px #ccc solid;padding-left:1ex">
My application has a need to lock a row in database for update. But when an=
other request comes to hit the same row, the query will be pending until th=
e previous lock is release. But this will hold all requests in the same thr=
ead.=A0<div>
<br></div><div>I have searched for several ways of get around of this issue=
. Not sure which is the best way to handle it. I would like to hear your ex=
perience about this issue. My potential solutions:</div><div>1. move the lo=
cked query to backend job. and return the response when the job finished.=
=A0</div>
<div>=A0 =A0 pro: clean and follow async manner of tornado</div><div>=A0 =
=A0 con: it may keep the connect open for longer time</div><div>2. Use asyn=
c db library to load.=A0</div><div>=A0 =A0 pro: fast and follow async manne=
r</div><div>
=A0 =A0 con: few async db library supports sqlalchemy for orm, which is imp=
ortant to us. I have tried twisted adbapi, and adb with MySQL. but the expe=
rience is not good (Maybe because I&#39;m new to twisted). gevent with psyc=
opg2 works with sqlalchemy, but I can&#39;t enjoy the async support from to=
rnado (I can only use gevent.spawn and join for async, and tornado is only =
for wsgi application).</div>
<div>3. Set short timeout to each query. (This is the last thing I want to =
do)</div><div>=A0 =A0 pro: easy and simple</div><div>=A0 =A0 con: Bad user =
experience bcz of timeout.=A0</div><div><br></div><div>I would like to know=
 if there is a general solution for issue like this.=A0</div>
<div><br></div><div>Thank you.</div></blockquote></div><br></div>

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