problem description
how does synchronized achieve visibility? after I added an empty Synchronize code block to thread B, thread B can correctly read that the value of I is 1, achieving visibility. Thread B will not stop without Synchronize code block. But even if an empty Synchronize code block is added, thread A should only execute iThread from main memory after executing Synchronize code block after locking, but I don"t think thread A has flushed iThread 1 from working memory to main memory yet, why this Synchronize code block can achieve I visibility.
related codes
public class b {
public static int i;
public static void main(String[] args) throws Exception {
Object o = new Object();
new Thread(() -> { //A
try {
TimeUnit.MILLISECONDS.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
i = 1;
while (true) {
}
}).start();
new Thread(() -> { //B
while (true) {
synchronized (o) { //B
}
if (i == 1) {
System.out.println("");
break;
}
}
}).start();
}}
topic description
sources of topics and their own ideas
related codes
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