CountDownLatch
jdk并发包的计数器,实现计数同步。
当使用线程池时,因为线程不会被销毁,所以使用join无法来阻塞线程。
// 创建 2 个线程的线程池
Executor executor =
Executors.newFixedThreadPool(2);
while(存在未对账订单){
// 计数器初始化为 2
CountDownLatch latch =
new CountDownLatch(2);
// 查询未对账订单
executor.execute(()-> {
pos = getPOrders();
latch.countDown();
});
// 查询派送单
executor.execute(()-> {
dos = getDOrders();
latch.countDown();
});
// 等待两个查询操作结束
latch.await();
// 执行对账操作
diff = check(pos, dos);
// 差异写入差异库
save(diff);
}
CyclicBarrier 处理步调一致
// 订单队列
Vector<P> pos;
// 派送单队列
Vector<D> dos;
// 执行回调的线程池
Executor executor =
Executors.newFixedThreadPool(1);
final CyclicBarrier barrier =
new CyclicBarrier(2, ()->{
executor.execute(()->check());
});
void check(){
P p = pos.remove(0);
D d = dos.remove(0);
// 执行对账操作
diff = check(p, d);
// 差异写入差异库
save(diff);
}
void checkAll(){
// 循环查询订单库
Thread T1 = new Thread(()->{
while(存在未对账订单){
// 查询订单库
pos.add(getPOrders());
// 等待
barrier.await();
}
});
T1.start();
// 循环查询运单库
Thread T2 = new Thread(()->{
while(存在未对账订单){
// 查询运单库
dos.add(getDOrders());
// 等待
barrier.await();
}
});
T2.start();
}