On Fri, Jul 31, 2009 at 12:41 PM, ramya <mail.ra...@gmail.com> wrote:
>
> Hi,
> I have python threaded application + Postgres. I am using Django's ORM
> to save to Postgres..
> I have concurrent save calls. Occasionally 2 threads save with the
> same primary key which leads to an issue.
>
> Postgres log:
> ERROR: duplicate key value violates unique constraint "store_pkey"
> STATEMENT: INSERT INTO "store" ("store_id", "address") VALUES
> (E'HAN277', E'101 Ocean Street')
>
> Code:
> In the code I see an IntegrityError. I tried different ways to handle
> this.
>
> a.
> try:
> a.save()
> except IntegrityError:
> pass
>
> This causes InternalError
>
> b. Tried to do transaction roll back.. but not sure.. As far as I
> understand you need to distinct save calls to have transactions
>
> sid = transaction.savepoint()
> try:
> row.save()
> except IntegrityError, e:
> transaction.savepoint_rollback(sid)
> pass
> transaction.commit()
> The first savepoint fails with
>
> AttributeError: 'NoneType' object has no attribute 'cursor'
>
>
> a. I read somewhere django is not 100% thread safe. Is it a good
> choice in my usecase. I was already using Django for other application
> and need an ORM.. So naturally I chose Django
> b. How to handle this situation.. Any comments.
One trick you could try is:
try:
a.save()
except IntegrityError:
wait(.1)
a.save()
This generally only works for lightly used multi-threaded application, and
you should be able to embed the Try-Except blocks to try more than twice.
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