However, in order for programs to take advantage of the speed increase that multiple cores provide, programs need to be able to be split into multiple streams of code. So, the more cores a program can use simultaneously, the faster the program will run. These processors have one or more “cores,” each capable of running one stream of code at the same time. In a modern computer, the processor, or CPU, is designed to run as many streams of code as possible at the same time. Running Functions at the Same Time with Goroutines Familiarity with Go functions, which you can find in the How to Define and Call Functions in Go tutorial.To set this up, follow the How To Install Go tutorial for your operating system. Finally, you’ll add more goroutines to the program to simulate a program running with multiple worker goroutines. Then you will add channels to that program to communicate between the running goroutines. First, you will create a program that uses goroutines to run multiple functions at once. In this tutorial, you will explore both goroutines and channels. Goroutines solve the difficulty of setting up and running concurrent code in a program, and channels solve the difficulty of safely communicating between the code running concurrently. Two features in Go, goroutines and channels, make concurrency easier when used together. To run programs faster, a programmer needs to design their programs to run concurrently, so that each concurrent part of the program can be run independently of the others. Being able to run code concurrently is becoming a larger part of programming as computers move from running a single stream of code faster to running more streams of code simultaneously. One of the popular features of the Go language is its first-class support for concurrency, or the ability of a program to do multiple things at once. In that case sync.Map performs worse than map+ sync.RWMutexīecause of reading from two internal maps.Īlso there is a counter that needs to be update when accessing dirty.The author selected the Diversity in Tech Fund to receive a donation as part of the Write for DOnations program. When there is both reading and updating sync.Map will have Speed metrics, but also can be the best in the reading case. Sync.Map is not only close to map+ sync.RWMutex on Of two map - one for reading and one for new elements. Sync.Map is complex struct, generally consisting Next, there is read iterating - simple map iterating. So, updating already existent key is simple,īefore iterating dirty is copied into read, If dirty is not initialized - it will be. The same reading is performed against dirty. If yes - the value is updated by atomic.CompareAndSwap. If there is only reading from a large map set up before,Īt first there is check against read - if there is a data behind the key. In this case this reading is equal to simple map (without mutex) reading. So, reading from sync.Map is most effective on read only. The copying will happen right after dirty access - mu is activatedĪmended field in readOnly struct (which is read).Īmended = true means there is non-empty dirty map in sync.Map. Important thing - if that counter's value is more that number of element in dirty,Įlements in dirty will be copied to read, counter will be reset. Misses - counter of access to dirty - is incremented. Then dirty is searched - the mu mutex is activated before. It is the most simple scenario - to return data from read. Let's take a look to sync.Map operations.Īt first read is accessed to check if there is a data behind the key. Trying to avoid using mutex when it is possible. So sync.Map has two internal maps ( read and dirty).īy using one map only for reading and second for writing sync.Map In that case mu mutex is used when dirty is accessed. It is used to place new elements generally and for read too. There is no inserts into read, that's why no mutex is used accessing read.ĭirty - a map, that stores other part of elements. Part of the data, that is used to read data by a key or to check that there is data behind that key. Let's take a look to sync.Map usage and it's sources.įar ago in year 2016, GO 1.9 was released withįollowing methods are available to work with sync.Map:
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