java-design-patterns | Design patterns implemented in Java | Architecture library
kandi X-RAY | java-design-patterns Summary
kandi X-RAY | java-design-patterns Summary
Design patterns are the best, formalized practices a programmer can use to solve common problems when designing an application or system. Design patterns can speed up the development process by providing tested, proven development paradigms. Reusing design patterns help prevent subtle issues that cause major problems, and it also improves code readability for coders and architects who are familiar with the patterns.
Support
Quality
Security
License
Reuse
Top functions reviewed by kandi - BETA
- init data .
- Handle usage processing event
- Create the view .
- Executes a new bake for the given parameters .
- Round round .
- Generates an iterable that returns the last element of the iterable .
- Creates a promotion .
- Handles incoming message .
- Setup the panel .
- Process event loop .
java-design-patterns Key Features
java-design-patterns Examples and Code Snippets
Community Discussions
Trending Discussions on java-design-patterns
QUESTION
I am a little confused as to why Optimistic Locking is actually safe. If I am checking the version at the time of retrieval with the version at the time of update, it seems like I can still have two requests enter the update block if the OS issues an interrupt and swaps the processes before the commit actually occurs. For example:
...ANSWER
Answered 2021-Mar-03 at 22:15Well... that's the optimistic part. The optimism is that it is safe. If you have to be certain it's safe, then that's not optimistic.
The example you show definitely is susceptible to a race condition. Not only because of thread scheduling, but also due to transaction isolation level.
A simple read in MySQL, in the default transaction isolation level of REPEATABLE READ, will read the data that was committed at the time your transaction started.
Whereas updating data will act on the data that is committed at the time of the update. If some other concurrent session has updated the row in the database in the meantime, and committed it, then your update will "see" the latest committed row, not the row viewed by your get method.
The way to avoid the race condition is to not be optimistic. Instead, force exclusive access to the record. Doveryai, no proveryai.
If you only have one app instance, you might use a critical section for this.
If you have multiple app instances, critical sections cannot coordinate other instances, so you need to coordinate in the database. You can do this by using pessimistic locking. Either read the record using a locking read query, or else you can use MySQL's user-defined locks.
Community Discussions, Code Snippets contain sources that include Stack Exchange Network
Vulnerabilities
No vulnerabilities reported
Install java-design-patterns
Search for a specific pattern by name. Can't find one? Please report a new pattern here.
Using tags such as Performance, Gang of Four or Data access.
Using pattern categories, Creational, Behavioral, and others.
Support
Reuse Trending Solutions
Find, review, and download reusable Libraries, Code Snippets, Cloud APIs from over 650 million Knowledge Items
Find more librariesStay Updated
Subscribe to our newsletter for trending solutions and developer bootcamps
Share this Page