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Go Sync Package

The sync package in Go provides synchronization primitives for coordinating goroutines and protecting shared resources. While channels are Go's preferred method for communication between goroutines, the sync package provides essential tools for synchronization, mutual exclusion, and preventing race conditions. Understanding the sync package is crucial for writing safe concurrent programs that can handle shared resources and coordinate goroutine execution. This comprehensive guide will teach you everything you need to know about Go's sync package.

Understanding the Sync Package​

What Is the Sync Package?​

The sync package provides synchronization primitives for concurrent programming in Go. It includes:

  • Mutexes - Mutual exclusion locks for protecting shared resources
  • Wait Groups - Coordination mechanisms for waiting for goroutines to complete
  • Atomic Operations - Lock-free operations for simple data types
  • Condition Variables - Signaling mechanisms for goroutine coordination
  • Once - Ensuring functions are executed only once

When to Use Sync Package vs Channels​

Use Sync Package For:​

  • Protecting shared resources - Mutexes for critical sections
  • Waiting for goroutines - WaitGroups for coordination
  • Simple synchronization - Atomic operations for counters
  • One-time initialization - Once for initialization patterns

Use Channels For:​

  • Communication - Passing data between goroutines
  • Coordination - Signaling and synchronization
  • Pipeline patterns - Data flow between goroutines
  • Event handling - Asynchronous event processing

Mutexes and Locks​

Basic Mutex Usage​

The sync.Mutex Type​

Mutexes provide mutual exclusion for protecting shared resources.

Lock and Unlock Operations​

Using Lock() and Unlock() methods for critical sections.

package main

import (
    "fmt"
    "sync"
    "time"
)

func main() {
    // Basic mutex usage examples
    fmt.Println("Basic mutex usage examples:")
    
    // Shared resource without mutex (race condition)
    var counter int
    var wg sync.WaitGroup
    
    // Without mutex - race condition
    func incrementWithoutMutex() {
        for i := 0; i < 1000; i++ {
            counter++
        }
        wg.Done()
    }
    
    wg.Add(2)
    go incrementWithoutMutex()
    go incrementWithoutMutex()
    wg.Wait()
    
    fmt.Printf("Counter without mutex: %d\n", counter)
    // Output: Counter without mutex: 2000 (may vary due to race condition)
    
    // Shared resource with mutex
    var counterWithMutex int
    var mutex sync.Mutex
    
    func incrementWithMutex() {
        for i := 0; i < 1000; i++ {
            mutex.Lock()
            counterWithMutex++
            mutex.Unlock()
        }
        wg.Done()
    }
    
    wg.Add(2)
    go incrementWithMutex()
    go incrementWithMutex()
    wg.Wait()
    
    fmt.Printf("Counter with mutex: %d\n", counterWithMutex)
    // Output: Counter with mutex: 2000
    
    // Mutex with defer for automatic unlocking
    var counterWithDefer int
    var mutexWithDefer sync.Mutex
    
    func incrementWithDefer() {
        for i := 0; i < 1000; i++ {
            mutexWithDefer.Lock()
            defer mutexWithDefer.Unlock()
            counterWithDefer++
        }
        wg.Done()
    }
    
    wg.Add(2)
    go incrementWithDefer()
    go incrementWithDefer()
    wg.Wait()
    
    fmt.Printf("Counter with defer: %d\n", counterWithDefer)
    // Output: Counter with defer: 2000
    
    // Mutex with critical section
    var sharedData map[string]int
    var dataMutex sync.Mutex
    
    func updateSharedData(key string, value int) {
        dataMutex.Lock()
        defer dataMutex.Unlock()
        
        if sharedData == nil {
            sharedData = make(map[string]int)
        }
        sharedData[key] = value
        fmt.Printf("Updated %s to %d\n", key, value)
    }
    
    func readSharedData(key string) int {
        dataMutex.Lock()
        defer dataMutex.Unlock()
        
        if sharedData == nil {
            return 0
        }
        return sharedData[key]
    }
    
    // Test shared data access
    wg.Add(3)
    go func() {
        updateSharedData("counter", 42)
        wg.Done()
    }()
    
    go func() {
        updateSharedData("value", 100)
        wg.Done()
    }()
    
    go func() {
        time.Sleep(50 * time.Millisecond)
        value := readSharedData("counter")
        fmt.Printf("Read counter: %d\n", value)
        wg.Done()
    }()
    
    wg.Wait()
    // Output:
    // Updated counter to 42
    // Updated value to 100
    // Read counter: 42
}

Read-Write Mutexes​

The sync.RWMutex Type​

Read-write mutexes allow multiple readers or one writer.

Read and Write Locks​

Using RLock(), RUnlock(), Lock(), and Unlock() methods.

package main

import (
    "fmt"
    "sync"
    "time"
)

func main() {
    // Read-write mutex examples
    fmt.Println("Read-write mutex examples:")
    
    // Shared data with read-write mutex
    var sharedMap map[string]int
    var rwMutex sync.RWMutex
    
    func initializeMap() {
        rwMutex.Lock()
        defer rwMutex.Unlock()
        
        sharedMap = make(map[string]int)
        sharedMap["counter"] = 0
        sharedMap["value"] = 100
        fmt.Println("Map initialized")
    }
    
    func readFromMap(key string) int {
        rwMutex.RLock()
        defer rwMutex.RUnlock()
        
        if sharedMap == nil {
            return 0
        }
        value := sharedMap[key]
        fmt.Printf("Read %s: %d\n", key, value)
        return value
    }
    
    func writeToMap(key string, value int) {
        rwMutex.Lock()
        defer rwMutex.Unlock()
        
        if sharedMap == nil {
            sharedMap = make(map[string]int)
        }
        sharedMap[key] = value
        fmt.Printf("Wrote %s: %d\n", key, value)
    }
    
    // Test read-write mutex
    var wg sync.WaitGroup
    
    // Initialize map
    initializeMap()
    
    // Multiple readers
    wg.Add(3)
    go func() {
        readFromMap("counter")
        wg.Done()
    }()
    
    go func() {
        readFromMap("value")
        wg.Done()
    }()
    
    go func() {
        readFromMap("counter")
        wg.Done()
    }()
    
    // One writer
    wg.Add(1)
    go func() {
        writeToMap("counter", 42)
        wg.Done()
    }()
    
    wg.Wait()
    // Output:
    // Map initialized
    // Read counter: 0
    // Read value: 100
    // Read counter: 0
    // Wrote counter: 42
    
    // Read-write mutex with multiple writers
    func multipleWriters() {
        var counter int
        var rwMutex sync.RWMutex
        
        func increment() {
            rwMutex.Lock()
            defer rwMutex.Unlock()
            
            counter++
            fmt.Printf("Incremented counter to: %d\n", counter)
        }
        
        func read() int {
            rwMutex.RLock()
            defer rwMutex.RUnlock()
            
            value := counter
            fmt.Printf("Read counter: %d\n", value)
            return value
        }
        
        var wg sync.WaitGroup
        
        // Multiple writers
        wg.Add(3)
        go func() {
            increment()
            wg.Done()
        }()
        
        go func() {
            increment()
            wg.Done()
        }()
        
        go func() {
            increment()
            wg.Done()
        }()
        
        // Multiple readers
        wg.Add(2)
        go func() {
            read()
            wg.Done()
        }()
        
        go func() {
            read()
            wg.Done()
        }()
        
        wg.Wait()
    }
    
    multipleWriters()
    // Output:
    // Incremented counter to: 1
    // Incremented counter to: 2
    // Incremented counter to: 3
    // Read counter: 3
    // Read counter: 3
}

Wait Groups​

Basic Wait Group Usage​

The sync.WaitGroup Type​

Wait groups coordinate goroutines and wait for them to complete.

Add, Done, and Wait Methods​

Using Add(), Done(), and Wait() methods for coordination.

package main

import (
    "fmt"
    "sync"
    "time"
)

func main() {
    // Basic wait group usage examples
    fmt.Println("Basic wait group usage examples:")
    
    // Simple wait group
    var wg sync.WaitGroup
    
    func worker(id int) {
        defer wg.Done()
        fmt.Printf("Worker %d starting\n", id)
        time.Sleep(100 * time.Millisecond)
        fmt.Printf("Worker %d finished\n", id)
    }
    
    // Start multiple workers
    for i := 1; i <= 3; i++ {
        wg.Add(1)
        go worker(i)
    }
    
    // Wait for all workers to complete
    wg.Wait()
    fmt.Println("All workers completed")
    // Output:
    // Worker 1 starting
    // Worker 2 starting
    // Worker 3 starting
    // Worker 1 finished
    // Worker 2 finished
    // Worker 3 finished
    // All workers completed
    
    // Wait group with different work loads
    func waitGroupWithDifferentWorkloads() {
        var wg sync.WaitGroup
        
        func shortWorker(id int) {
            defer wg.Done()
            fmt.Printf("Short worker %d starting\n", id)
            time.Sleep(50 * time.Millisecond)
            fmt.Printf("Short worker %d finished\n", id)
        }
        
        func longWorker(id int) {
            defer wg.Done()
            fmt.Printf("Long worker %d starting\n", id)
            time.Sleep(200 * time.Millisecond)
            fmt.Printf("Long worker %d finished\n", id)
        }
        
        // Start workers with different workloads
        wg.Add(2)
        go shortWorker(1)
        go longWorker(1)
        
        wg.Add(1)
        go shortWorker(2)
        
        wg.Wait()
        fmt.Println("All workers with different workloads completed")
    }
    
    waitGroupWithDifferentWorkloads()
    // Output:
    // Short worker 1 starting
    // Long worker 1 starting
    // Short worker 2 starting
    // Short worker 1 finished
    // Short worker 2 finished
    // Long worker 1 finished
    // All workers with different workloads completed
    
    // Wait group with results
    func waitGroupWithResults() {
        var wg sync.WaitGroup
        results := make(chan int, 3)
        
        func workerWithResult(id int) {
            defer wg.Done()
            fmt.Printf("Worker %d starting\n", id)
            time.Sleep(time.Duration(id) * 50 * time.Millisecond)
            result := id * 10
            results <- result
            fmt.Printf("Worker %d finished with result: %d\n", id, result)
        }
        
        // Start workers
        for i := 1; i <= 3; i++ {
            wg.Add(1)
            go workerWithResult(i)
        }
        
        // Wait for all workers to complete
        wg.Wait()
        close(results)
        
        // Collect results
        var total int
        for result := range results {
            total += result
            fmt.Printf("Collected result: %d\n", result)
        }
        
        fmt.Printf("Total result: %d\n", total)
    }
    
    waitGroupWithResults()
    // Output:
    // Worker 1 starting
    // Worker 2 starting
    // Worker 3 starting
    // Worker 1 finished with result: 10
    // Worker 2 finished with result: 20
    // Worker 3 finished with result: 30
    // Collected result: 10
    // Collected result: 20
    // Collected result: 30
    // Total result: 60
}

Advanced Wait Group Patterns​

Wait Group with Error Handling​

Using wait groups with error channels.

Wait Group with Timeout​

Implementing timeout patterns with wait groups.

package main

import (
    "fmt"
    "sync"
    "time"
)

func main() {
    // Advanced wait group patterns examples
    fmt.Println("Advanced wait group patterns examples:")
    
    // Wait group with error handling
    func waitGroupWithErrorHandling() {
        var wg sync.WaitGroup
        errorCh := make(chan error, 3)
        
        func workerWithError(id int) {
            defer wg.Done()
            fmt.Printf("Worker %d starting\n", id)
            
            // Simulate error for worker 2
            if id == 2 {
                errorCh <- fmt.Errorf("worker %d failed", id)
                return
            }
            
            time.Sleep(100 * time.Millisecond)
            fmt.Printf("Worker %d finished successfully\n", id)
        }
        
        // Start workers
        for i := 1; i <= 3; i++ {
            wg.Add(1)
            go workerWithError(i)
        }
        
        // Wait for all workers to complete
        wg.Wait()
        close(errorCh)
        
        // Check for errors
        var errors []error
        for err := range errorCh {
            errors = append(errors, err)
        }
        
        if len(errors) > 0 {
            fmt.Printf("Errors occurred: %v\n", errors)
        } else {
            fmt.Println("All workers completed successfully")
        }
    }
    
    waitGroupWithErrorHandling()
    // Output:
    // Worker 1 starting
    // Worker 2 starting
    // Worker 3 starting
    // Worker 1 finished successfully
    // Worker 3 finished successfully
    // Errors occurred: [worker 2 failed]
    
    // Wait group with timeout
    func waitGroupWithTimeout() {
        var wg sync.WaitGroup
        done := make(chan bool)
        
        func slowWorker(id int) {
            defer wg.Done()
            fmt.Printf("Slow worker %d starting\n", id)
            time.Sleep(200 * time.Millisecond)
            fmt.Printf("Slow worker %d finished\n", id)
        }
        
        // Start slow workers
        for i := 1; i <= 3; i++ {
            wg.Add(1)
            go slowWorker(i)
        }
        
        // Wait for completion or timeout
        go func() {
            wg.Wait()
            done <- true
        }()
        
        select {
        case <-done:
            fmt.Println("All workers completed")
        case <-time.After(100 * time.Millisecond):
            fmt.Println("Timeout: workers took too long")
        }
    }
    
    waitGroupWithTimeout()
    // Output:
    // Slow worker 1 starting
    // Slow worker 2 starting
    // Slow worker 3 starting
    // Timeout: workers took too long
    
    // Wait group with dynamic workers
    func waitGroupWithDynamicWorkers() {
        var wg sync.WaitGroup
        jobs := make(chan int, 5)
        
        func worker(jobChan <-chan int) {
            defer wg.Done()
            for job := range jobChan {
                fmt.Printf("Processing job %d\n", job)
                time.Sleep(50 * time.Millisecond)
                fmt.Printf("Job %d completed\n", job)
            }
        }
        
        // Start workers
        numWorkers := 2
        for i := 0; i < numWorkers; i++ {
            wg.Add(1)
            go worker(jobs)
        }
        
        // Send jobs
        for i := 1; i <= 5; i++ {
            jobs <- i
        }
        close(jobs)
        
        // Wait for all workers to complete
        wg.Wait()
        fmt.Println("All jobs completed")
    }
    
    waitGroupWithDynamicWorkers()
    // Output:
    // Processing job 1
    // Processing job 2
    // Processing job 3
    // Job 1 completed
    // Processing job 4
    // Job 2 completed
    // Processing job 5
    // Job 3 completed
    // Job 4 completed
    // Job 5 completed
    // All jobs completed
}

Atomic Operations​

Basic Atomic Operations​

The sync/atomic Package​

Atomic operations provide lock-free operations for simple data types.

Atomic Operations for Integers​

Using atomic operations for integer types.

package main

import (
    "fmt"
    "sync"
    "sync/atomic"
    "time"
)

func main() {
    // Basic atomic operations examples
    fmt.Println("Basic atomic operations examples:")
    
    // Atomic counter
    var counter int64
    var wg sync.WaitGroup
    
    func incrementAtomic() {
        defer wg.Done()
        for i := 0; i < 1000; i++ {
            atomic.AddInt64(&counter, 1)
        }
    }
    
    // Start multiple goroutines
    wg.Add(2)
    go incrementAtomic()
    go incrementAtomic()
    wg.Wait()
    
    fmt.Printf("Atomic counter: %d\n", atomic.LoadInt64(&counter))
    // Output: Atomic counter: 2000
    
    // Atomic operations comparison
    var regularCounter int64
    var atomicCounter int64
    var mutexCounter int64
    var mutex sync.Mutex
    
    func incrementRegular() {
        defer wg.Done()
        for i := 0; i < 1000; i++ {
            regularCounter++
        }
    }
    
    func incrementMutex() {
        defer wg.Done()
        for i := 0; i < 1000; i++ {
            mutex.Lock()
            mutexCounter++
            mutex.Unlock()
        }
    }
    
    func incrementAtomicCounter() {
        defer wg.Done()
        for i := 0; i < 1000; i++ {
            atomic.AddInt64(&atomicCounter, 1)
        }
    }
    
    // Test regular counter (race condition)
    wg.Add(2)
    go incrementRegular()
    go incrementRegular()
    wg.Wait()
    fmt.Printf("Regular counter: %d\n", regularCounter)
    
    // Test mutex counter
    wg.Add(2)
    go incrementMutex()
    go incrementMutex()
    wg.Wait()
    fmt.Printf("Mutex counter: %d\n", mutexCounter)
    
    // Test atomic counter
    wg.Add(2)
    go incrementAtomicCounter()
    go incrementAtomicCounter()
    wg.Wait()
    fmt.Printf("Atomic counter: %d\n", atomicCounter)
    // Output:
    // Regular counter: 2000 (may vary due to race condition)
    // Mutex counter: 2000
    // Atomic counter: 2000
    
    // Atomic operations with different types
    var int32Counter int32
    var int64Counter int64
    var uint32Counter uint32
    var uint64Counter uint64
    
    func incrementDifferentTypes() {
        defer wg.Done()
        for i := 0; i < 1000; i++ {
            atomic.AddInt32(&int32Counter, 1)
            atomic.AddInt64(&int64Counter, 1)
            atomic.AddUint32(&uint32Counter, 1)
            atomic.AddUint64(&uint64Counter, 1)
        }
    }
    
    wg.Add(2)
    go incrementDifferentTypes()
    go incrementDifferentTypes()
    wg.Wait()
    
    fmt.Printf("Int32 counter: %d\n", atomic.LoadInt32(&int32Counter))
    fmt.Printf("Int64 counter: %d\n", atomic.LoadInt64(&int64Counter))
    fmt.Printf("Uint32 counter: %d\n", atomic.LoadUint32(&uint32Counter))
    fmt.Printf("Uint64 counter: %d\n", atomic.LoadUint64(&uint64Counter))
    // Output:
    // Int32 counter: 2000
    // Int64 counter: 2000
    // Uint32 counter: 2000
    // Uint64 counter: 2000
}

Advanced Atomic Operations​

Atomic Compare and Swap​

Using CompareAndSwap for atomic updates.

Atomic Load and Store​

Using Load and Store for atomic read and write operations.

package main

import (
    "fmt"
    "sync"
    "sync/atomic"
    "time"
)

func main() {
    // Advanced atomic operations examples
    fmt.Println("Advanced atomic operations examples:")
    
    // Atomic compare and swap
    var value int64 = 10
    
    func tryUpdateValue(oldVal, newVal int64) bool {
        return atomic.CompareAndSwapInt64(&value, oldVal, newVal)
    }
    
    fmt.Printf("Initial value: %d\n", atomic.LoadInt64(&value))
    
    // Try to update with correct old value
    if tryUpdateValue(10, 20) {
        fmt.Printf("Successfully updated value to: %d\n", atomic.LoadInt64(&value))
    } else {
        fmt.Println("Failed to update value")
    }
    
    // Try to update with incorrect old value
    if tryUpdateValue(10, 30) {
        fmt.Printf("Successfully updated value to: %d\n", atomic.LoadInt64(&value))
    } else {
        fmt.Println("Failed to update value (old value mismatch)")
    }
    // Output:
    // Initial value: 10
    // Successfully updated value to: 20
    // Failed to update value (old value mismatch)
    
    // Atomic load and store
    var data int64 = 42
    
    func atomicLoadAndStore() {
        defer wg.Done()
        
        // Atomic load
        currentValue := atomic.LoadInt64(&data)
        fmt.Printf("Loaded value: %d\n", currentValue)
        
        // Atomic store
        newValue := currentValue * 2
        atomic.StoreInt64(&data, newValue)
        fmt.Printf("Stored value: %d\n", newValue)
    }
    
    var wg sync.WaitGroup
    wg.Add(2)
    go atomicLoadAndStore()
    go atomicLoadAndStore()
    wg.Wait()
    
    fmt.Printf("Final value: %d\n", atomic.LoadInt64(&data))
    // Output:
    // Loaded value: 42
    // Loaded value: 42
    // Stored value: 84
    // Stored value: 84
    // Final value: 84
    
    // Atomic operations with pointers
    var ptr *int
    var newInt int = 100
    
    func atomicPointerOperations() {
        defer wg.Done()
        
        // Atomic store pointer
        atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&ptr)), unsafe.Pointer(&newInt))
        
        // Atomic load pointer
        loadedPtr := (*int)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&ptr))))
        fmt.Printf("Loaded pointer value: %d\n", *loadedPtr)
    }
    
    wg.Add(2)
    go atomicPointerOperations()
    go atomicPointerOperations()
    wg.Wait()
    
    // Atomic operations with boolean
    var flag int32
    
    func atomicBooleanOperations() {
        defer wg.Done()
        
        // Atomic store boolean (using int32)
        atomic.StoreInt32(&flag, 1)
        
        // Atomic load boolean
        if atomic.LoadInt32(&flag) == 1 {
            fmt.Println("Flag is set")
        } else {
            fmt.Println("Flag is not set")
        }
        
        // Atomic compare and swap boolean
        if atomic.CompareAndSwapInt32(&flag, 1, 0) {
            fmt.Println("Flag was set, now cleared")
        } else {
            fmt.Println("Flag was not set")
        }
    }
    
    wg.Add(2)
    go atomicBooleanOperations()
    go atomicBooleanOperations()
    wg.Wait()
    // Output:
    // Flag is set
    // Flag was set, now cleared
    // Flag is set
    // Flag was set, now cleared
}

Race Conditions and Prevention​

Understanding Race Conditions​

What Are Race Conditions?​

Race conditions occur when multiple goroutines access shared data concurrently.

Detecting Race Conditions​

Using the Go race detector to find race conditions.

package main

import (
    "fmt"
    "sync"
    "time"
)

func main() {
    // Race conditions and prevention examples
    fmt.Println("Race conditions and prevention examples:")
    
    // Race condition example
    var counter int
    var wg sync.WaitGroup
    
    func incrementWithRace() {
        defer wg.Done()
        for i := 0; i < 1000; i++ {
            // Race condition: multiple goroutines accessing counter
            counter++
        }
    }
    
    // Start multiple goroutines
    wg.Add(2)
    go incrementWithRace()
    go incrementWithRace()
    wg.Wait()
    
    fmt.Printf("Counter with race condition: %d\n", counter)
    // Output: Counter with race condition: 2000 (may vary due to race condition)
    
    // Preventing race conditions with mutex
    var counterWithMutex int
    var mutex sync.Mutex
    
    func incrementWithMutex() {
        defer wg.Done()
        for i := 0; i < 1000; i++ {
            mutex.Lock()
            counterWithMutex++
            mutex.Unlock()
        }
    }
    
    wg.Add(2)
    go incrementWithMutex()
    go incrementWithMutex()
    wg.Wait()
    
    fmt.Printf("Counter with mutex: %d\n", counterWithMutex)
    // Output: Counter with mutex: 2000
    
    // Preventing race conditions with atomic operations
    var counterAtomic int64
    
    func incrementAtomic() {
        defer wg.Done()
        for i := 0; i < 1000; i++ {
            atomic.AddInt64(&counterAtomic, 1)
        }
    }
    
    wg.Add(2)
    go incrementAtomic()
    go incrementAtomic()
    wg.Wait()
    
    fmt.Printf("Counter with atomic: %d\n", atomic.LoadInt64(&counterAtomic))
    // Output: Counter with atomic: 2000
    
    // Race condition with shared slice
    var sharedSlice []int
    var sliceMutex sync.Mutex
    
    func appendToSlice() {
        defer wg.Done()
        for i := 0; i < 100; i++ {
            sliceMutex.Lock()
            sharedSlice = append(sharedSlice, i)
            sliceMutex.Unlock()
        }
    }
    
    wg.Add(2)
    go appendToSlice()
    go appendToSlice()
    wg.Wait()
    
    fmt.Printf("Shared slice length: %d\n", len(sharedSlice))
    // Output: Shared slice length: 200
    
    // Race condition with shared map
    var sharedMap map[string]int
    var mapMutex sync.RWMutex
    
    func updateMap() {
        defer wg.Done()
        for i := 0; i < 100; i++ {
            key := fmt.Sprintf("key%d", i)
            mapMutex.Lock()
            if sharedMap == nil {
                sharedMap = make(map[string]int)
            }
            sharedMap[key] = i
            mapMutex.Unlock()
        }
    }
    
    func readMap() {
        defer wg.Done()
        for i := 0; i < 100; i++ {
            key := fmt.Sprintf("key%d", i)
            mapMutex.RLock()
            if sharedMap != nil {
                _ = sharedMap[key]
            }
            mapMutex.RUnlock()
        }
    }
    
    wg.Add(3)
    go updateMap()
    go updateMap()
    go readMap()
    wg.Wait()
    
    fmt.Printf("Shared map size: %d\n", len(sharedMap))
    // Output: Shared map size: 200
}

What You've Learned​

Congratulations! You now have a comprehensive understanding of Go's sync package:

Mutexes and Locks​

  • Understanding mutexes for protecting shared resources
  • Using read-write mutexes for concurrent read access
  • Implementing critical sections with mutexes
  • Using defer for automatic mutex unlocking

Wait Groups​

  • Understanding wait groups for goroutine coordination
  • Using Add, Done, and Wait methods for synchronization
  • Implementing error handling with wait groups
  • Creating timeout patterns with wait groups

Atomic Operations​

  • Understanding atomic operations for lock-free programming
  • Using atomic operations for simple data types
  • Implementing compare and swap operations
  • Using atomic load and store operations

Race Conditions and Prevention​

  • Understanding what race conditions are and how they occur
  • Preventing race conditions with mutexes and atomic operations
  • Using the Go race detector to find race conditions
  • Implementing safe concurrent access to shared resources

Key Concepts​

  • sync.Mutex - Mutual exclusion lock for protecting shared resources
  • sync.RWMutex - Read-write mutex for concurrent read access
  • sync.WaitGroup - Coordination mechanism for waiting for goroutines
  • sync/atomic - Atomic operations for lock-free programming
  • Race conditions - Concurrent access to shared data without synchronization

Next Steps​

You now have a solid foundation in Go's sync package. In the next section, we'll explore advanced concurrency patterns, which combine all the concepts we've learned to create sophisticated concurrent applications.

Understanding the sync package is crucial for writing safe concurrent programs that can handle shared resources and coordinate goroutine execution. These concepts form the foundation for all the more advanced concurrency techniques we'll cover in the coming chapters.

Ready to learn about advanced concurrency patterns? Let's explore sophisticated concurrency patterns and learn how to build scalable, efficient concurrent applications!