01 2015-12

Rapberry Pi 2 运行 Docker

Ahui ⋅ Tagged: linux network

情景

Rapberry Pi 2 一个
Mac OS X 系统

安装步骤

下载Rapberry Pi 2系统并解压

wget http://downloads.hypriot.com/hypriot-rpi-20151115-132854.img.zip
unzip hypriot-rpi-20151115-132854.img.zip

系统简介

Detailed Features of HypriotOS “Hector”
a modern operating system based on Raspbian Jessie
a recent Raspberry Pi firmware and Device Tree to support a huge range of hardware add-ons
a kernel optimized for Docker-awesomeness: Kernel 4.1.12 with support for OverlayFS
support for Raspberry Pi 1 & 2 with the same SD card image
Docker Engine 1.9.0
Docker Compose 1.5.1
Docker Machine 0.4.1
Docker Swarm 1.0.0
support for network hotplugging
out-of-the-box support for WiFi
support for Avahi (aka mDNS aka Apple Bonjour)
support for Open vSwitch
our own package repository to easily update individual components

检查下载是否正确

shasum -a 256 hypriot-rpi-20151115-132854.img.zip
089bc64fc5f050f263aa65a67fac5fe48f8721c51f8a31f3d96fa426bc04674d  hypriot-rpi-20151115-132854.img.zip

准备好一张容量最少4G 的microSD卡. 查找其系统编号

diskutil list

	...
	/dev/disk2
   	#:                       TYPE NAME                    SIZE       	IDENTIFIER
   	0:     FDisk_partition_scheme                        *4.0 GB     disk2
   	1:                 DOS_FAT_32 NO NAME                 4.0 GB   
   	...

这里为/dev/disk2,别看错.

取消挂载

diskutil unmountdisk /dev/disk2

写入系统到 SD 卡,设备名 disk2前有个字母 'r', 这样能加速写入

sudo dd if=hypriot-rpi-20151115-132854.img of=/dev/rdisk2 bs=1m
1430+1 records in
1430+0 records out
1499463680 bytes transferred in 112.464700 secs (13332750 bytes/sec)

sd 卡放在 pi 2上,启动吧.

11 2015-11

数据库存取速度优化

Ahui ⋅ Tagged: network python

sqlite3

使用场景

使用 pony 作为 orm读取 20w 条左右数据

慢

取得所有字段,会自动封装成对象 select(u for u in User)

优化

只取需要的字段 select(u.id for u in User)

redis

使用场景

使用 redis.py 作为  写入 20w 条左右数据

慢

m.incr('u_'+u[:7])

优化

使用连接池

pool = redis.ConnectionPool(host='127.0.0.1', port=6379, db=15)
m = redis.StrictRedis(connection_pool=pool)

使用批量提交

	
pipe = m.pipeline()
pipe.incr('u_'+u[:7])
pipe.set()
pipe.execute()

20 2015-08

Ubuntu 14 grub 2 取消重启挂住

Ahui ⋅ Tagged: linux network

Ubuntu 14.04 在升级内核或是不安全断电情况下,重启后GRUB 会停留在系统选择界面,并不会自动超时,需要手动选择并按回车才能继续启动. 在不方便接触物理机或 VPS 远程开机时,是个很麻烦的事.

主要原因是/boot/grub/grub.cfg 把 timeout 设置成了'-1'.

  if [ "${recordfail}" = 1 ] ; then
   set timeout=-1
  else
   if [ x$feature_timeout_style = xy ] ; then
     set timeout_style=hidden
     set timeout=0
   # Fallback hidden-timeout code in case the timeout_style feature is
   # unavailable.
   elif sleep --interruptible 0 ; then
     set timeout=0
   fi
  fi

grub.cfg 会被重写覆盖,得修改/etc/default/grub,加入一行