concurrency
the way a computer system works on several tasks at the same time or during overlapping time periods
In computing, the ability or practice of running multiple tasks, processes, threads, or requests during overlapping periods, so they can make progress independently.
the situation in which two or more things happen or exist at the same time
The fact that two or more events, conditions, or states happen, exist, or are true at the same time.
agreement between people, ideas, or decisions, though agreement or concurrence is usually more natural
Formal and uncommon: agreement between opinions, decisions, or actions; concurrence.
- Base: concurrency
- Plural: concurrencies, concurrency
concurrency control
1Coordinating simultaneous data access
ways to stop simultaneous computer operations from damaging or mixing up data
- The database relies on concurrency control to keep transactions from corrupting shared data.
- Good concurrency control lets many users edit records without overwriting each other.
- The team added concurrency control after two updates were sometimes saved in the wrong order.
- Concurrency control protects shared data.
- The app needs better concurrency control.
concurrency issue
1Bug from overlapping operations
a computer bug caused by several tasks happening at the same time
- The duplicate charges were traced to a concurrency issue in the payment service.
- Concurrency issues are hard to reproduce because they depend on timing.
- The developers fixed a concurrency issue that occurred when two users edited the same file.
- The crash was a concurrency issue.
- Concurrency issues can be hard to find.
concurrency limit
1Maximum simultaneous operations
the largest number of things a system lets run at the same time
- The API has a concurrency limit of 20 requests per account.
- We raised the concurrency limit during the sale to reduce waiting times.
- If you exceed the concurrency limit, new jobs stay in the queue until one finishes.
- The concurrency limit is 10 users.
- The server rejected the request because of the concurrency limit.
concurrency model
1System for managing concurrent work
the method a programming system uses to organize several tasks at the same time
- Actors, threads, and async/await represent different concurrency models.
- Choosing the right concurrency model can make the code easier to reason about.
- JavaScript's event loop is a central part of its concurrency model.
- The language has a simple concurrency model.
- The team chose an actor-based concurrency model.
high concurrency
1Many simultaneous system operations
a situation where many computer tasks or users are active at the same time
- The server stayed stable under high concurrency during the ticket sale.
- High concurrency can expose timing bugs that never appear in simple tests.
- The new architecture was designed to handle high concurrency with fewer machines.
- The app can handle high concurrency.
- High concurrency made the bug appear.
optimistic concurrency control
1Conflict checking without early locks
a way to allow edits first and check later whether another edit caused a conflict
- With optimistic concurrency control, the system checks the row version before saving.
- Optimistic concurrency control worked well because most users edited different records.
- The update failed because optimistic concurrency control detected a newer version of the document.
- Optimistic concurrency control checks for conflicts before saving.
- The save failed because another user changed the record.
pessimistic concurrency control
1Conflict prevention with locks
a way to stop conflicts by locking data before people or programs change it
- The bank used pessimistic concurrency control for transfers that changed account balances.
- Pessimistic concurrency control can reduce conflicts, but it may slow the system down.
- The application locked the record as part of its pessimistic concurrency control strategy.
- Pessimistic concurrency control uses locks.
- The record was locked before the update.