Ask about Transaction

Dear ALL"

I would like to ask, what is it true that rails already supports
transaction although we do not put ActiveRecord::Base.transaction in our
ruby controller or model script? - My DB ENGINE is InnoDB -

I did test in web browser with putting delay process inside of script to
make 2 concurrent process having collision, but the fact at final, they
are handled with transaction, i do not put any
ActiveRecord::Base.transaction or ModelName.transaction script there.

Example :
They are 10 items in stock. 2 concurrent process wanted to take 1 item
from stocks. If it is not having ActiveRecord::Base.transaction in
method the result would be 9, but the fact is it is 8 (10-1-1). Look the
tables process below without transaction in console (table 1) & web
browser (table 2):

http://pastie.caboo.se/194711

How come my test in console and web browser are difference ??

On 10 May 2008, at 05:06, Rails T. wrote:

Dear ALL"

I would like to ask, what is it true that rails already supports
transaction although we do not put ActiveRecord::Base.transaction in
our
ruby controller or model script? - My DB ENGINE is InnoDB -

I’m not quite sure what you’re asking, but rails does wrap the
validation, before_save, save and after_save sequence in a transaction.

method the result would be 9, but the fact is it is 8 (10-1-1). Look
the
tables process below without transaction in console (table 1) & web
browser (table 2):

http://pastie.caboo.se/194711

How come my test in console and web browser are difference ??
If you’re just running a single mongrel/webrick instance then when you
test with your browser you’re not actually executed 2 things at the
same time (since a rails instance only handles one request at a time).

Fred
(PS: if you want to insert a delay, the sleep method is rather handier
than counting to a million)

My Fred Brother thank you for your answer. Sleep mode is good idea and
also you give me information about :

If you’re just running a single mongrel/webrick instance then when you
test with your browser you’re not actually executed 2 things at the
same time (since a rails instance only handles one request at a time).

I test : I open 2 web browser and do concurrent process by accessing the
same method for adding 1 item to cart, but it looks like having
transaction in my method, whereas I do not put
ActiveRecord::Base.transaction there. Since you explained above, now i
understand why my concurent process looks like having transaction,
because it handles one request at a time and other can only follow.

Thank you,
Reinhart
http://teapoci.blogspot.com

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