system Understanding Systemd Units and Unit Files
what is the init process(pid=1); a replacement of sysV and upstart;
初始化系统：start the rest of system 管理服务/进程 the unit(resouce) type service: an applicaton; target: g group of unit; timer: like cron socket: the servie active by a socket the process of a application start: ExecStart stop: use ExecStop= send signTerm, after 90s, send SINGKILL configure file file path:
`/usr/lib/systemd/system/: install by package manager /etc/systemd/system/ : user local create 1 2 3 4 5 6 7 8 9 10 11 [Unit] Description=<description about this service> [Service] User=<user e.
basic principle KISS: Keep it simple, stupied
微服务架构 基础概念 服务: 熔断 降级 熔断: 被动 降级: 主动
使用本地方法替换远程服务。
create a micro k8s promethues kafka go rpc
what is elk roles:
logstash:
ingest datas; transform it send it to a stash beat: data collection
elasticsearch: store data;
logstash 1. collection data configure 1 2 3 4 5 6 7 8 9 10 11 12 13 14 # ingest data input{ } # transform data filter{ } # data go to where output{ } grok: 1.translate plain text to structure data; 2. add,remove field filter example 1 2 3 4 5 filter { grok { match => { "message" => ['%{TIMESTAMP_ISO8601:time} %{LOGLEVEL:logLevel} %{GREEDYDATA:logMessage}'] } } } 2.
px rem What’s The Difference Between PX, EM, REM, %, VW, and VH?
px is absoulute rem is relative
openvpn openvpn config 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 local 0.0.0.0 port 1184 local 0.0.0.0 port 1184 proto tcp dev tun ca /data/openvpn/conf/keys/ca.crt cert /data/openvpn/conf/keys/vpnserver.crt key /data/openvpn/conf/keys/vpnserver.key # This file should be kept secret dh /data/openvpn/conf/keys/dh2048.pem server 10.7.0.0 255.255.255.0 ifconfig-pool-persist ipp.txt push "route 192.168.0.0 255.255.0.0" #<E8><B7><AF><E7><94><B1>ip<E8><A6><81><E6><A0><B9><E6><8D><AE><E6><9C><AC><E6><9C><BA>ip<E5><81><9A><E5><8F><82><E8><80><83> client-to-client keepalive 10 120 cipher AES-256-CBC comp-lzo persist-key persist-tun status openvpn-status.
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the full process of html dom tree
cssdom tree
render tree
lyaout
node:
size position paint
compositing
parse block vs render block both will block ;
parse-blocking: js
render-blocking
encounter external resources how html be loaded fetch html parse html encounter script and css; script: stop parsing; fetch js, parse and excute it css: just continuing parsing 4.continue parsing 1. ready state 1. loading load and parse html
js will breakdown the parsing
