This question is not about a specific framework. but I'm currently working with asp.net core.

The problem I'm facing is the concurrent update of a resource in the web application (race condition). I'm not talking about synchronizing edits to a wiki document by let's say conditionals HTTP requests. both requests are received by web application at the same time. for example first request query a database to get a number and then it tries to increment that number by one. meanwhile, the second request gets the same number before the first request commits its change to DB. now the number only incremented by one. What comes to my mind is locking each resource when it is being updated.

are there any other options available? this must be a common issue in every web application but I can't find that many solutions for this problem on the internet.


1 Answer 1


These issues should generally be handled at the lowest possible level, i.e. in the database.

Your changes to the database should be atomic, so the process of changing the database is non-interruptible and either completely succeeds or completely fails. In SQL databases, you can use START TRANSACTION statements to do this. E.g. you can use a transaction to make a table read-only for other connections for the duration of the transaction. Since transactions involve locks, they do limit performance. But in most scenarios, it is more important to have consistent data than to have corrupted data more quickly.

If you cannot use transactions (e.g. because there are HTTP requests between requesting the number and changing the number), then you can do a test-and-set update: guard the UPDATE statement by adding a WHERE clause that asserts that row is in the expected state. For example, you could manually verify that it still contains the previous value, or add a timestamp or version column for more complex data. You must then make sure that you update/increment that column on each change to the row. If this column changed, the update fails.

Related to this is the idea of never updating rows but only adding new records. When querying the table, only the most recent result is selected. The table is now more like a transaction log. However, this is rather close to implementing your own database engine, and there are databases (possibly NoSQL databases) that implement this behaviour directly.

In some scenarios, it is not important that each change is applied and applied in order, but only that the final result is correct. It is then possible to simply let the last update win. But this requires that each update provides the complete data for the record, and doesn't just update one or two fields. This is often the most desirable solution in distributed scenarios where you have to synchronise multiple databases, e.g. data on a server and cached data on a device that may perform changes while offline.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.