[汇总]高并发，构架&项目经验

by leelight · Published October 3, 2022 · Updated April 15, 2024

多线程并发消费如果在极短的时间内，连续发送重复的消息，就会被不同的线程消费。即使在代码中有这样的判断：

Product oldProduct = query(hashCode);
if(oldProduct == null) {
    productMapper.insert(product);
}

Product oldProduct = query(hashCode);

if(oldProduct == null) {

productMapper.insert(product);

}

在插入数据之前，先判断该数据是否已经存在，只有不存在才会插入。但由于在并发情况下，不同的线程都判断商品数据不存在，于是同时进行了插入操作，所以就产生了重复数据。

方案：

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