Differences among concurrent, parallel, serial, synchronous and asynchronous

1. Concurrent ： Two or more events occur at the same time interval

In a single processor system , Only one program can be executed at a time , So microscopically, these programs can only be executed alternately in time . In a multiprocessor system , These programs that can be executed concurrently can be allocated to multiple processors , Implement parallel execution , That is, each processor is used to process a program that can be executed concurrently , such , Multiple programs can be executed at the same time .

2. parallel ： Two or more events occur at the same time , Multiple tasks can be performed simultaneously

3. Serial ： When referring to multiple tasks , Each task is performed in sequence , You can't move on to the next... Until you finish one

4. Sync ： Synchronization is sequential execution , After executing one, execute the next , Need to wait 、 Coordinated operation

5. asynchronous ： Asynchrony is independence , Continue to do your own thing while waiting for an event , There is no need to wait for this event to complete , You can follow up . Thread is a way to realize asynchrony , Asynchrony is the ultimate goal , Multithreading is just a means for us to realize asynchrony