Latch 什么是latch: 锁是数据库系统区别与文件系统的一个关键特性.锁机制用于管理对共享资源的并发访问.Innodb存储引擎在行级别上对表数据上锁,这固然不错.但是Innodb也会在多个地方使用锁,从而允许多种不同资源提供并发访问.例如,操作缓冲池汇总的LRU列表,删除.添加.移动LRU列表中的元素,为了保证一致性,必须有锁的介入,这就是latch锁. latch与lock的区别 latch一般称为闩锁(轻量级别的锁),因为其要求锁定的时间必须非常短.若持续的时间长,则应用的性能会非常差

/**********************************************************************//** Puts new extents to the free list if there are free extents above the free limit. If an extent happens to contain an extent descriptor page, the extent is put to the FSP_FREE

/* The transaction handle; every session has a trx object which is freed only when the session is freed; in addition there may be session-less transactions rolling back after a database recovery */ typedef struct trx_struct trx_t; struct trx_struct{

获得区描述符 xdes entry 的offset /********************************************************************//** Gets pointer to a the extent descriptor of a page. The page where the extent descriptor resides is x-locked. This function no longer extends the data

参考http://wqtn22.iteye.com/blog/1820436 http://blog.jcole.us/2013/01/10/btree-index-structures-in-innodb/ 根据index 找到合适记录的游标cursor #define btr_pcur_open_on_user_rec(i,t,md,l,c,m) \ btr_pcur_open_on_user_rec_func(i,t,md,l,c,__FILE__,__LINE__,m) /*******

/**********************************************************************//** Initializes the space header of a new created space and creates also the insert buffer tree root if space == 0. */ UNIV_INTERN void fsp_header_init( /*============*/ ulint sp

移除 node, node->prev直接指向node->next /********************************************************************//** Removes a node. */ UNIV_INTERN void flst_remove( /*========*/ flst_base_node_t* base, /*!< in: pointer to base node of list */ flst_node_t

/********************************************************************//** This is the general function used to get access to a database page. @return pointer to the block or NULL */ UNIV_INTERN buf_block_t* buf_page_get_gen( /*=============*/ ulint s

/**********************************************************************//** Gets a pointer to the space header and x-locks its page. @return pointer to the space header, page x-locked */ UNIV_INLINE fsp_header_t* fsp_get_space_header( /*=============

申请一个段 /**********************************************************************//** Creates a new segment. @return the block where the segment header is placed, x-latched, NULL if could not create segment because of lack of space */ UNIV_INTERN buf_blo

从inode page中申请inode entry inode = fsp_alloc_seg_inode(space_header, mtr); /**********************************************************************//** Allocates a new file segment inode. @return segment inode, or NULL if not enough space */ static fse

/**************************************************************//** NOTE! The following macros should be used instead of buf_page_get_gen, to improve debugging. Only values RW_S_LATCH and RW_X_LATCH are allowed in LA! */ #define buf_page_get(SP, ZS,

/********************************************************************//** Adds a node as the last node in a list. */ UNIV_INTERN void flst_add_last( /*==========*/ flst_base_node_t* base, /*!< in: pointer to base node of list */ flst_node_t* node, /*

innodb 存储引擎,创建一个表 本文分析创建一个段.待叙,主要说明是如何创建一文件,并在文件中分配一个索引. 上面是创建一个表的调用图.创建文件和创建一个btr /**********************************************************************//** Allocates a new file segment inode. @return segment inode, or NULL if not enough space */ s

http://mysql.taobao.org/monthly/2015/07/05/ MySQL · 引擎特性 · InnoDB index lock前世今生 前言 InnoDB并发过程中使用两类锁进行同步. 1. 事务锁 维护在不同的Isolation level下数据库的Atomicity和Consistency两大基本特性. InnoDB定义了如下的lock mode: /* Basic lock modes */ enum lock_mode { LOCK_IS = 0, /* int

[问题描述] 最近碰到有台MySQL实例出现了MySQL服务短暂hang死,表现为瞬间的并发线程上升,连接数暴增. 排查Error Log文件中有page_cleaner超时的信息,引起我们的关注: 2019-08-24T23:47:09.361836+08:00 0 [Note] InnoDB: page_cleaner: 1000ms intended loop took 24915ms. The settings might not be optimal. (flushed=182 and

InnoDB 中的锁实现 原贴:InnoDB 锁系统及死锁检测实现分析 InnoDB 中,所有事务加的行锁通过一个全局的 hash 表 lock_sys 维护: /* The lock system */ lock_sys_t *lock_sys = NULL; /** The lock system struct */ struct lock_sys_t { char pad1[INNOBASE_CACHE_LINE_SIZE]; /*!< padding to prevent other m