Difference between revisions of "Locks and Deadly Locks"
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GO CMDLCK | GO CMDLCK | ||
| − | [[RPG]] | + | [[RPG]] reads an entire record into a program which will be updating the record on some account, item, customer, order, whatever. Different programs in the hands of different users might be updating different fields such as: |
* Inventory Totals | * Inventory Totals | ||
* $ Financials | * $ Financials | ||
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We want to avoid conflicts between the different people who might be updating different fields in the same records at the same time. | We want to avoid conflicts between the different people who might be updating different fields in the same records at the same time. | ||
| + | |||
| + | Without locks, there is the danger that several programs might read in the data on some record into the program work area, change one or more fields, and be doing this concurrently with some other program. Thus when one program writes copy of the data back to the file, with one field updated, the other programs still have copy of the data prior to this update, then when they write the data back with their field updated, the earlier program's update is lost. | ||
== Deadly Locks == | == Deadly Locks == | ||
'''Deadly Locks''' are a symptom of poor software design and/or poor implementation practices. | '''Deadly Locks''' are a symptom of poor software design and/or poor implementation practices. | ||
Revision as of 15:29, 31 May 2005
Locks
Locks are normal.
GO CMDLCK
RPG reads an entire record into a program which will be updating the record on some account, item, customer, order, whatever. Different programs in the hands of different users might be updating different fields such as:
- Inventory Totals
- $ Financials
- Alphabetical descriptions
We want to avoid conflicts between the different people who might be updating different fields in the same records at the same time.
Without locks, there is the danger that several programs might read in the data on some record into the program work area, change one or more fields, and be doing this concurrently with some other program. Thus when one program writes copy of the data back to the file, with one field updated, the other programs still have copy of the data prior to this update, then when they write the data back with their field updated, the earlier program's update is lost.
Deadly Locks
Deadly Locks are a symptom of poor software design and/or poor implementation practices.
