# 20250926 Java应用系统调试与调优技术

**Repository Path**: itmuch/20250926-pafc

## Basic Information

- **Project Name**: 20250926 Java应用系统调试与调优技术
- **Description**: Java应用系统调试与调优技术
- **Primary Language**: Java
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2025-09-26
- **Last Updated**: 2025-09-26

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# README

> 备忘
>
> * 提高性能意识
> * 数据库是重点
> * 池化技术
> * exexutors
> * jvm gc日志怎么看，如何快速定位内存 cpu如何看



# 课程相关素材

https://gitee.com/itmuch/20250926-pafc





09:30  - 11:30





# kill 







```
user   1   -   n    address



```



```
select * from user a left join address b 
on a.id = b.user_id 
where a.name = 'x' and b.is_del = 0
```



```
select * from user a left join address b 
on a.id = b.user_id and b.is_del = 0
where a.name = 'x'
```







# **select count(*) from user where xxxx**