Mutex Semaphore Atomic
以下是建立1000個協程
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| @Test
fun coroutine10() = runBlocking<Unit> {
var count = 0
List(1000) {
GlobalScope.launch { count++ }
}.joinAll()
println(count)
}
|
Mutex 鎖
結果居然不是1000。
使用Mutex鎖，讓要存取count變數的1000個協程「們」，都只能排隊存取，無法所有人同時搶同一個資源。
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| @Test
fun coroutine10() = runBlocking<Unit> {
var count = 0
val mutex = Mutex()
List(1000) {
GlobalScope.launch {
mutex.withLock { count++ }
}
}.joinAll()
println(count)
}
|
Semphore 信號
使用信號來通知協程可以允許修改資源。
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| @Test
fun coroutine11() = runBlocking<Unit> {
var count = 0
val semaphore = Semaphore(permits = 1)
List(1000) {
GlobalScope.launch {
semaphore.withPermit { count++ }
}
}.joinAll()
println(count)
}
|
原子AtomicInteger
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| @Test
fun coroutine12() = runBlocking<Unit> {
var count = AtomicInteger(0)
val semaphore = Semaphore(permits = 1)
List(1000) {
GlobalScope.launch {
count.incrementAndGet()
}
}.joinAll()
println(count.get())
}
|