chenchun

import java.io.*;
import java.util.*;
import sun.jvm.hotspot.memory.*;
import sun.jvm.hotspot.oops.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.tools.*;

public class DumpClassURL extends Tool {
    public void run() {

chenchun

import java.io.*;
import java.util.*;
import sun.jvm.hotspot.memory.*;
import sun.jvm.hotspot.oops.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.tools.*;
import sun.jvm.hotspot.utilities.*;

public class DirectMemorySize extends Tool {

chenchun

#!/bin/bash

# Get IP for specified host using 'http://ping.eu/ping', then write it to hosts.

if [ $# -ne 1 ]; then
    echo "Usage: $0 host"
    echo "  e.g. # $0 baidu.com"
    exit 0
fi

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# bind Ctrl-a as command prefix
set -g prefix C-a
unbind C-b

bind-key -r Space next-layout
bind ^z run "tmux-zoom"

chenchun

// Use Gists to store code you would like to remember later on
console.log(window); // log the "window" object to the console

chenchun

## ip address info
root@6f62c03f8f5a:/go/src/github.com/docker/libnetwork# ip ad
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: br-55bac522026e: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default 
    link/ether 02:42:b4:4b:95:ee brd ff:ff:ff:ff:ff:ff

chenchun

#!/usr/bin/env bash

function setup_overlay() {
    ip netns add overlay
    ip netns exec overlay ip li ad dev br0 type bridge
    ip li add dev vxlan42 type vxlan id 42 l2miss l3miss proxy learning dstport 4789
    ip link set vxlan42 netns overlay
    ip netns exec overlay ip li set dev vxlan42 name vxlan1
    ip netns exec overlay ip li set dev vxlan1 master br0
    ip li add dev vetha1 mtu 1450 type veth peer name vetha2 mtu 1450

chenchun

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

chenchun

package main

import (
	"net"
	"runtime"
	"fmt"

	"github.com/vishvananda/netns"
	"os"
)

chenchun

https://github.com/golang/go/wiki/cgo

# foo.go:

package gocallback

import "fmt"

/*