shared_memory 共享内存
Table of Contents

共享内存

跨worker进程进行通信

Nginx官方模块

ngx_http_lua_api

openresty 的核心模块

rbtree

插入删除非常快

ngx_stream_limit_conn_module

ngx_http_limit_conn_module

ngx_stream_limit_req_module

http cache

ngx_http_file_cache
ngx_http_proxy_module
ngx_http_scgi_module
ngx_http_uwsgi_module
ngx_http_fastcgi_module

ssl

ngx_http_ssl_module
ngx_mail_ssl_module
ngx_stream_ssl_module

单链表

将需要共享的元素串起来

ngx_http_upstream_zone_module

ngx_stream_upstream_zone_module

使用的场景

所有需要多worker进程协同配合的场景。例如upstream负载均衡算法，或者limit_conn、limit_req等。一般指令中有zone关键字都是共享内存。

slab

ngx_slab_stat

下载ngx_slab_stat

wget http://tengine.taobao.org/download/tengine-2.2.2.tar.gz
tar -xf tengine-2.2.2.tar.gz
cd tengine-2.2.2/

~/tengine-2.2.2/modules/ngx_slab_stat# ls -la ngx_http_slab_stat_module.c
-rw-r--r-- 1 128966 users 6627 Jan 28  2018 ngx_http_slab_stat_module.c

重新编译openresty

cd openresty-1.13.6.2/
./configure --add-module=/root/tengine-2.2.2/modules/ngx_slab_stat/
make

配置openresty

http {
    lua_shared_dict dogs 10m;
    server {
location = /slab_stat {
    slab_stat;
}

location /set {
    content_by_lua_block {
        local dogs = ngx.shared.dogs
        dogs:set("Jim", 8)
        ngx.say("STORED")
    }
}

location /get {
    content_by_lua_block {
        local dogs = ngx.shared.dogs
        ngx.say(dogs:get("Jim"))
    }
}
    }
}

统计slab使用状态

# curl localhost:80/set
STORED

# curl localhost:80/get
8

# curl localhost:80/slab_stat
* shared memory: dogs
total:       10240(KB) free:       10168(KB) size:           4(KB)
pages:       10168(KB) start:00007F680E0A7000 end:00007F680EA97000
slot:           8(Bytes) total:           0 used:           0 reqs:           0 fails:           0
slot:          16(Bytes) total:           0 used:           0 reqs:           0 fails:           0
slot:          32(Bytes) total:         127 used:           1 reqs:           1 fails:           0
slot:          64(Bytes) total:           0 used:           0 reqs:           0 fails:           0
slot:         128(Bytes) total:          32 used:           2 reqs:           2 fails:           0
slot:         256(Bytes) total:           0 used:           0 reqs:           0 fails:           0
slot:         512(Bytes) total:           0 used:           0 reqs:           0 fails:           0
slot:        1024(Bytes) total:           0 used:           0 reqs:           0 fails:           0
slot:        2048(Bytes) total:           0 used:           0 reqs:           0 fails:           0