Weakness of Transaction in Rails

Rails
1

Dear All:

I have done my test for 2 actions do simultaneously for the same
command. Here is my approvement.

Window DOS 1

F:\ruby\tiesto> ruby test/unit/item_test.rb
Loaded suite test/unit/item_test
Started
.
Finished in 42.078 seconds.

1 tests, 0 assertions, 0 failures, 0 errors

Windows DOS 2

F:\ruby\tiesto>ruby test/unit/item_test.rb
Loaded suite test/unit/item_test
Started
.
Finished in 42.125 seconds.

1 tests, 0 assertions, 0 failures, 0 errors

SCRIPT item_test.rb

require File.dirname( FILE) + ‘/…/test_helper’

class ItemTest < Test::Unit:: TestCase

def test_what
CD = item.find(:first)

Item.transaction do
CD.modification
end

end
end

SCRIPT in Item.rb (Active Record)

class Item < ActiveRecord: :Base

def modification

#delaying process
for z in 1…100000000
end

update_attributes( :stock => stock-1)

end

TABLE BEFORE TESTS RUN

ID | ITEM | QTY |

1 | HEAVEN | 10 |

After 2 Windows Run TEST TOGETHER.

TABLE AFTER EXECUTIONS

ID | ITEM | QTY |

1 | HEAVEN | 9 |

It is not what i expected, it should be 10 - 1 -1 = 8, NOT 9. In other
case i did put Item.transaction do there.

What is your suggestion about it ???

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

2

CORRECTION TABLE :

ID | ITEM | STOCK |

1 | HEAVEN | 10 |

After 2 Windows Run TEST TOGETHER.

TABLE AFTER EXECUTIONS

ID | ITEM | STOCK |

1 | HEAVEN | 9 |

REGARDS,
Reinhart
http://teapoci.blogspot.com

3

On May 8, 5:05 pm, Rails T. [email protected]
wrote:

It is not what i expected, it should be 10 - 1 -1 = 8, NOT 9. In other
case i did put Item.transaction do there.

What is your suggestion about it ???

You need locking, not transactions. the problem is that both scripts
load the initial version (ie with quantity = 10). when the second one
completes it ignores the changes made by the first one.

Fred

4

On May 8, 5:30 pm, Rails T. [email protected]
wrote:

Thanks my bro, fred. Here is my second experiment

Are you tables MyISAM? MyISAM tables don’t support transactions or row
level locks (AR’s optimistic locking is probably a better fit for this
anyway) so this would be entirely surprising (but using transactions
is necessary for pessimistic locking; the lock is held for the
duration of the current transaction

Fred

5

Yes it is ENGINE=MyISAM :((

How I can move it? I use SQLYOG and XAMP, it says ENGINE=MyISAM, MySQL
GUI v5.14.

Thank you,
Reinhart

6

On May 8, 6:22 pm, Rails T. [email protected]
wrote:

Yes it is ENGINE=MyISAM :((

How I can move it? I use SQLYOG and XAMP, it says ENGINE=MyISAM, MySQL
GUI v5.14.

set it to innodb. No idea what SQLYOG or XAMP are. Also I noticed that
for some reason you’re doing this from unit tests which (normally)
destroy and reload the test database each time you run them

Fred

7

Thanks my bro, fred. Here is my second experiment

SCRIPT item_test.rb

require File.dirname( FILE) + ‘/…/test_helper’

class ItemTest < Test::Unit:: TestCase

def test_what

Item.transaction do
CD = item.find(:first, :lock=>true)
CD.modification
end

end
end

DOS in WINDOW 1

F:\ruby\project_dev>ruby test/unit/barang_terpesan_test.rb
Loaded suite test/unit/barang_terpesan_test
Started
.
Finished in 39.734 seconds.

1 tests, 0 assertions, 0 failures, 0 errors

DOS in WINDOW 2

F:\ruby\project_dev>ruby test/unit/barang_terpesan_test.rb
Loaded suite test/unit/barang_terpesan_test
Started
.
Finished in 40.703 seconds.

1 tests, 0 assertions, 0 failures, 0 errors

And No Changes.

TABLE BEFORE EXECUTIONS

ID | ITEM | STOCK |

1 | HEAVEN | 10 |

!!!
TABLE AFTER EXECUTIONS
!!!

ID | ITEM | STOCK |

1 | HEAVEN | 9 |

I have done too with :

ActiveRecord::Base.transaction do
CD = item.find(:first, :lock=>true)
CD.modification
end

And no changes, the result still the same.

Reinhart
http://teapoci.blogspot.com

8

I cant find to convert MyISAM to InnoDB fast and safety. I have lot of
table tobe converted, any suggestion?

Thanks,
Reinhart

9

On Thu, May 8, 2008 at 10:44 AM, Rails T.
[email protected] wrote:

I cant find to convert MyISAM to InnoDB fast and safety.

See the MySQL doc for ALTER TABLE

–
Hassan S. ------------------------ [email protected]

10

What is the best way to test it out of unit test? Thank you.

11

On May 8, 6:37 pm, Rails T. [email protected]
wrote:

What is the best way to test it out of unit test? Thank you.

script/runner for example or just require boot.rb and environment.rb

Fred

12

ALTER TABLE items ENGINE=INNODB

Not work, I use phpMyAdmin at XAMP and SQLYOG