From d0671c80525b2e95a0f1bd86f7d2178f315c2418 Mon Sep 17 00:00:00 2001 From: hmao Date: Tue, 24 Nov 2020 06:16:52 -0800 Subject: [PATCH] Update Rocket.md --- Rocket.md | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/Rocket.md b/Rocket.md index 36df622..6add0ca 100644 --- a/Rocket.md +++ b/Rocket.md @@ -1005,6 +1005,9 @@ select的几大缺点:   对于第三个缺点,epoll没有这个限制,它所支持的FD上限是最大可以打开文件的数目,这个数字一般远大于2048,举个例子,在1GB内存的机器上大约是10万左右,具体数目可以cat /proc/sys/fs/file-max察看,一般来说这个数目和系统内存关系很大。 +### 乐观锁和悲观锁 + + ### 秒杀并发情况下库存为负数问题 1. for update显示加锁 @@ -1018,3 +1021,5 @@ select quantity from products WHERE id=3 for update; quantity = select quantity from products WHERE id=3; update products set quantity = ($quantity-1) WHERE id=3 and queantity = $quantity; +# +