On 06/23/2016 03:30 PM, Chung wrote:
We're occasionally seeing this exception thrown out of
mapper.configure_mappers when using SQLSoup in our webapp:
|
File"/home/glados/.virtualenvs/pod-glance/local/lib/python2.7/site-packages/sqlsoup.py",line
455,in__getattr__
returnself.entity(attr)
File"/home/glados/.virtualenvs/pod-glance/local/lib/python2.7/site-packages/sqlsoup.py",line
452,inentity
returnself.map_to(attr,tablename=attr,schema=schema)
File"/home/glados/.virtualenvs/pod-glance/local/lib/python2.7/site-packages/sqlsoup.py",line
363,inmap_to
mapper_args
File"/home/glados/.virtualenvs/pod-glance/local/lib/python2.7/site-packages/sqlsoup.py",line
172,in_class_for_table
fork inmappr.iterate_properties:
File"/home/glados/.virtualenvs/pod-glance/local/lib/python2.7/site-packages/sqlalchemy/orm/mapper.py",line
1819,initerate_properties
configure_mappers()
File"/home/glados/.virtualenvs/pod-glance/local/lib/python2.7/site-packages/sqlalchemy/orm/mapper.py",line
2677,inconfigure_mappers
formapper inlist(_mapper_registry):
File"/usr/lib/python2.7/weakref.py",line 327,initerkeys
forwr inself.data.iterkeys():
RuntimeError:dictionary changed size during iteration
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I saw a previous thread about this
<https://groups.google.com/forum/#!searchin/sqlalchemy/%22RuntimeError$3A$20dictionary$20changed$20size$20during$20iteration%22/sqlalchemy/Qcwzn_GqUdQ/7n28bZqfPKYJ>
and
indeed we are creating new SQLSoup instances per request not per
process. But I also note that since then, it seems that sqlalchemy does
use a _CONFIGURE_MUTEX to avoid unsynchronized reference to
_mapper_registry.
Any idea what might be causing this?
adding new mappers while the configure() step is running would cause
this, so if you are building mapped classes in requests, this would happen.
It's incredibly inefficient to create a SQLSoup mapped class on a
per-request basis, because you're not only mapping, you're also
reflecting the table structure from the database, so unless you have
potentially millions of tables I'd look to set up all the mappers you
need up front. The automap extension (which supersedes SQLSoup) makes
this pretty simple.
Thanks,
Chung
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