ThreadPoolExecutor中的ctl变量
所属分类 java
浏览量 1448
private final AtomicInteger ctl = new AtomicInteger(ctlOf(RUNNING, 0));
private static final int COUNT_BITS = Integer.SIZE - 3;
private static final int CAPACITY = (1 << COUNT_BITS) - 1;
// runState is stored in the high-order bits
private static final int RUNNING = -1 << COUNT_BITS;
private static final int SHUTDOWN = 0 << COUNT_BITS;
private static final int STOP = 1 << COUNT_BITS;
private static final int TIDYING = 2 << COUNT_BITS;
private static final int TERMINATED = 3 << COUNT_BITS;
// Packing and unpacking ctl
private static int runStateOf(int c) { return c & ~CAPACITY; }
private static int workerCountOf(int c) { return c & CAPACITY; }
private static int ctlOf(int rs, int wc) { return rs | wc; }
ctl包含两个值
workerCount 线程数
runState 线程池的状态, Running,Shutdown,Stop,Tidying,Terminate
29位表示workerCount,3位表示当前线程池的状态。
高3位状态值,低28位 线程数
runState is stored in the high-order bits
COUNT_BITS Integer.SIZE-3 明线程数 用29位表示
CAPACITY 左移29位 减一 ,
ctl&CAPACITY 获取当前线程数
ThreadpoolCtlTest.java
import java.util.concurrent.atomic.AtomicInteger;
public class ThreadpoolCtlTest {
private static final int COUNT_BITS = Integer.SIZE - 3;
private static final int CAPACITY = (1 << COUNT_BITS) - 1;
// runState is stored in the high-order bits
private static final int RUNNING = -1 << COUNT_BITS;
private static final int SHUTDOWN = 0 << COUNT_BITS;
private static final int STOP = 1 << COUNT_BITS;
private static final int TIDYING = 2 << COUNT_BITS;
private static final int TERMINATED = 3 << COUNT_BITS;
// Packing and unpacking ctl
private static int runStateOf(int c) {
return c & ~CAPACITY;
}
private static int workerCountOf(int c) {
return c & CAPACITY;
}
private static int ctlOf(int rs, int wc) {
return rs | wc;
}
private final static AtomicInteger ctl = new AtomicInteger(ctlOf(RUNNING, 0));
private static boolean isRunning(int c) {
return c < SHUTDOWN;
}
private static void printCtl(){
int c = ctl.get();
System.out.print(c+",");
System.out.print(isRunning(c)+",");
System.out.print(runStateOf(c)+",");
System.out.println(workerCountOf(c));
}
public static void main(String[] args) throws Exception {
System.out.println(0+","+ (~0));
System.out.println(1+","+ (~1));
System.out.println(CAPACITY);
System.out.println(~CAPACITY);
printCtl();
ctl.set(ctlOf(RUNNING, 3));
printCtl();
ctl.set(ctlOf(SHUTDOWN, 3));
printCtl();
}
}
输出
0,-1
1,-2
536870911
-536870912
-536870912,true,-536870912,0
-536870909,true,-536870912,3
3,false,0,3
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