Adding Customized HTTP Header in HTTPServletRequest in Jetty

Sometimes we need Adding some customized HTTP header in Jetty's Request.

Here is a way to change Request.getHeader() using java.lang.instrument and javassist.

contents of MANIFEST.MF:

command to compile and pack jar:
javac -classpath ./javassist.jar HeaderAgent.java
jar -cmf MANIFEST.MF sslagent.jar HeaderAgent.class

adding following option to your java command, then Request.getHeader() method will be customized after Request.class loaded.



[emacs]go to end-of-buffer ignore whitespaces


;;we always need goto end-of-buffer, so we bind it to C-. for simple.
;;sometimes we need goto end-of-buffer, but ignore whitespaces at end-of-buffer
;;so by give end-of-buffer an advice, it'll switch between these points, when you
;;continue typing C-.
(defadvice end-of-buffer (around move-backward-skip-whitespace)
  "Never use tabs for alignment."
  (let ((point-before-move (point)))
    (if (and (eq point-before-move (point)) (eq last-command this-command))
        (progn (search-backward-regexp "[^\n\s-]\\W*")
(ad-activate 'end-of-buffer)
(define-key my-keys-minor-mode-map (kbd "C-.") 'end-of-buffer)



[emacs] compare with clipboard like IntelliJ IDEA


(defun compare-with-clipboard  ()
  "compare current buffer with contents in clipboard"
  (let ((clipboard-buffer (get-buffer-create "*clipbord*"))
        (orig-buffer (current-buffer)))
    (switch-to-buffer clipboard-buffer)
    (delete-region (point-min) (point-max))
    (ediff-buffers clipboard-buffer orig-buffer)))



Monitor process file operations by windbg command


* Monitor windows process activities by set breakpoint on API, and print out the parameter contents.

0:000> bp kernel32!CreateFileW ".echo ---------------------------------------;kL;du poi(@esp+4);gu;.echo =======;r eax;g"  
0:000> g  
ModLoad: 62c20000 62c29000   C:/WINDOWS/system32/LPK.DLL  
ModLoad: 77180000 77283000   C:/WINDOWS/WinSxS/x86_Microsoft.Windows.Common-Controls_6595b64144ccf1df_6.0.2600.2982_x-ww_ac3f9c03/comctl32.dll  
ChildEBP RetAddr    
0012e374 7c814d65 kernel32!CreateFileW  
0012e5dc 7c801d3a kernel32!BasepLoadLibraryAsDataFile+0x125  
0012e640 7c8171dd kernel32!LoadLibraryExW+0x178  
0012e66c 7c81715d kernel32!BasepSxsFindSuitableManifestResourceFor+0x51  
0012e96c 7720b80d kernel32!CreateActCtxW+0x69e  
0012eba4 7720b83f comctl32_77180000!SHFusionInitializeIDCC+0x83  
0012ebb8 7720b857 comctl32_77180000!SHFusionInitializeID+0x12  
0012ebc8 771841a9 comctl32_77180000!SHFusionInitialize+0xf  
0012ebdc 77184267 comctl32_77180000!_ProcessAttach+0x32  
0012ebe8 7c9211a7 comctl32_77180000!LibMain+0x21  
0012ec08 7c93cbab ntdll!LdrpCallInitRoutine+0x14  
0012ed10 7c936178 ntdll!LdrpRunInitializeRoutines+0x344  
0012efbc 7c9362da ntdll!LdrpLoadDll+0x3e5  
0012f264 7c801bb9 ntdll!LdrLoadDll+0x230  
0012f2cc 7c80ae5c kernel32!LoadLibraryExW+0x18e  
0012f2e0 77f5b1a3 kernel32!LoadLibraryW+0x11  
0012f504 766a1110 SHLWAPI!LoadLibraryWrapW+0x51  
0012f53c 766a10af WININET!SHFusionLoadLibrary+0x29  
0012f548 766a107d WININET!DelayLoadCC+0x15  
0012f77c 766a0ff7 WININET!SHFusionInitializeIDCC+0x92  
0012e3d0  "C:/WINDOWS/WindowsShell.Manifest"  
0012e410  ""  
ChildEBP RetAddr    
0012f8cc 7c801a4f kernel32!CreateFileW  
0012f8f0 76d357ff kernel32!CreateFileA+0x30  
0012f954 76d3570a iphlpapi!OpenIPDriver+0x115  
0012f99c 76d35454 iphlpapi!OpenTCPDriver+0xee  
0012f9d0 76d35351 iphlpapi!DllMain+0x157  
0012f9f0 7c9211a7 iphlpapi!_DllMainCRTStartup+0x52  
0012fa10 7c93cbab ntdll!LdrpCallInitRoutine+0x14  
0012fb18 7c94173e ntdll!LdrpRunInitializeRoutines+0x344  
0012fc94 7c941639 ntdll!LdrpInitializeProcess+0x1131  
0012fd1c 7c92eac7 ntdll!_LdrpInitialize+0x183  
00000000 00000000 ntdll!KiUserApcDispatcher+0x7  
7ffdfc00  "//./Ip"  
*** ERROR: Symbol file could not be found.  Defaulted to export symbols for C:/Program Files/Tencent/QQ2009/Bin/KernelUtil.dll -   
ChildEBP RetAddr    
0012fc34 0044a69c kernel32!CreateFileW  
*** ERROR: Module load completed but symbols could not be loaded for QQ.exe  
WARNING: Stack unwind information not available. Following frames may be wrong.  
0012fca8 004029bd KernelUtil!Version::Init+0x8c  
0012ff08 004027d9 QQ+0x29bd  
0012ff28 00402635 QQ+0x27d9  
0012ffc0 7c816fd7 QQ+0x2635  
0012fff0 00000000 kernel32!BaseProcessStart+0x23  
00c8eca8  "C:/Program Files/Tencent/QQ2009/"  
00c8ece8  "Bin/vi.dat"  
ChildEBP RetAddr    
0012eab4 0044a2ad kernel32!CreateFileW  
WARNING: Stack unwind information not available. Following frames may be wrong.  
0012fbb4 0044a4ea KernelUtil!Util::URL::OpenUrlWithTT+0x1cd  
0012fc4c 0044a6fc KernelUtil!Version::GetBuildVer+0xca  
0012fca8 004029bd KernelUtil!Version::Init+0xec  
0012ff08 004027d9 QQ+0x29bd  
0012ff28 00402635 QQ+0x27d9  
0012ffc0 7c816fd7 QQ+0x2635  
0012fff0 00000000 kernel32!BaseProcessStart+0x23  
00c8ede0  "C:/Program Files/Tencent/QQ2009/"  
00c8ee20  "Bin/QQ.exe"  



Start from helloworld.asm


* asm
** gdb:::
resource                ::$ http://www.chemie.fu-berlin.de/chemnet/use/info/gdb/gdb_toc.html
stop at main            ::$ b main | r
view register           ::info registers
show single reg         ::print/(d|t|x) $eax
show memory value       ::x/<num>(c|d|x)(b|h|w)    x/42cb &output
(gdb) x/s $edi+28
0x600104 <output+28>:    "GenuineIntel'\n"
** common 
Code of helloworld.asm::        
EatMsg: db "hello world", 10
EatLen: equ $-EatMsg
global _start
        mov eax, 4
        mov ebx, 1
        mov ecx, EatMsg
        mov edx, EatLen
        int 80H

        mov eax, 1
        mov ebx, 0
        int 80H
Command to build::
[vagrant@vagrant-centos-6-64 vagrant]$ nasm -f elf -g -F stabs helloworld.asm 
helloworld.asm  helloworld.o
[vagrant@vagrant-centos-6-64 vagrant]$ ld -o helloworld helloworld.o -melf_i386
helloworld  helloworld.asm  helloworld.o
[vagrant@vagrant-centos-6-64 vagrant]$ ./helloworld 
hello world

dump all sections       ::$ objdump -D eatsyscall
08048080 <_start>:      ||break *_start+1 then %epi will contains 0x08048080
 8048080:       90                      nop
 8048081:       b8 04 00 00 00          mov    $0x4,%eax
 8048086:       bb 01 00 00 00          mov    $0x1,%ebx
gcc output              ::$ gcc -S ctest.c
gcc -E                  ::$ gcc -E ctest.c
compile wit debug info  ::$ gcc -gstabs -gp -o ctest ctest.c 
dump code with assembly ::$ objdump -S ctest
int foo()
  400684:       55                      push   %rbp
  400685:       48 89 e5                mov    %rsp,%rbp
  400688:       48 83 ec 10             sub    $0x10,%rsp
  40068c:       e8 a7 fe ff ff          callq  400538 <mcount@plt>  ||<--insert by -gp for gprof

#include <stdio.h>
int main()
  400504:       55                      push   %rbp
  400505:       48 89 e5                mov    %rsp,%rbp
  printf("Hello, World!\n");
  400508:       bf 18 06 40 00          mov    $0x400618,%edi
  40050d:       e8 de fe ff ff          callq  4003f0 <puts@plt>
  400512:       bf 00 00 00 00          mov    $0x0,%edi
  400517:       e8 e4 fe ff ff          callq  400400 <exit@plt>
dump out dynamic symbol table entries::$ objdump -T ctest
ctest:     file format elf64-x86-64
0000000000000000  w   D  *UND*  0000000000000000              __gmon_start__
0000000000000000      DF *UND*  0000000000000000  GLIBC_2.2.5 puts
0000000000000000      DF *UND*  0000000000000000  GLIBC_2.2.5 exit
0000000000000000      DF *UND*  0000000000000000  GLIBC_2.2.5 __libc_start_main
dump dynamic entries::$ readelf -d cpuid2
Dynamic section at offset 0x2b0 contains 15 entries:
  Tag        Type                         Name/Value
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
show used share libs::$ ldd cpuid2
        libc.so.6 => /lib64/libc.so.6 (0x00007f0e83eb4000)
        /lib/ld64.so.1 => /lib64/ld-linux-x86-64.so.2 (0x00007f0e8424f000)
mov:: movl(long word) movw(16-bit word) movb(byte)  | movl %eax, %ebx | movw %ax %bx | movb %al %bh
conditional move:: movl value, %ecx | cmp %ebx, %ecx | cmova %ebx, %ecx
XCHG::exchange value between two general purpos registers, or betwen a register and a memory location.
when one of the operands is a memory location, the processor's LOCK signal is automatically asserted,
to turns the instruction into an atomic instruction in multiple processor environment.
CMPXCHG:: cmpxchg src dest | compare dest with EAX,AX,or AL. if equal, load src to dest. 
otherwise load dest to EAX, AX, or AL.  
unconditional branches::jump calls interrupts
call: 1) push the $eip, modifies the %eip to point to called function address 
      2) call function and ret 
      3) pop %eip to continue
asm function template::
    pushl %ebp
    movl %esp, %ebp
    <normal function code>
    movl %ebp, %esp
    popl %ebp

software interrupts::are provided by OS to enable app to tap info function into the OS. (system calls).

** resources



What Emacs can do?

code alignment  (gif video)

column editing (gif video)

WEIBO, git, git blame, rainbow (gif video)

dynamic selection and Code browsing (gif video)

org-mode + googledriver to manage your notes in one file (gif video)

    weibo and music
    Task management in TDD



Reading notes of Learning the vi and Vim Editors


* Notes of Learning the vi and Vim Editors

repeat last command                             :: .

Movements                                       :: w W b B e E ( ) { } [[   0 ^ n| $ gg G 200G
move to char                                    :: fx Fx tx Tx   (; continue forward and ' for backward)
move on screen                                  :: H M L 2H 
Actions                                         :: d c y

append at line end                              :: A
insert at line begin                            :: I
delete char                                     :: x X

open line up and down                           :: o O
paste up and line                               :: p P
delete line and insert                          :: S   //same as ddi or cc
(number prefix)write 50 *                       :: 50i*

set-mark in vi                                  :: mx (x for any letter)
goto mark                                       :: `x

delete line                                     :: dd
delete from cursor to end                       :: D
undo                                            :: u U
redo                                            :: ctrl+R

center current line                             :: Z.

paste from named delete buffer                  :: "3p
yank to named buffera                           :: "a4yy
append to named buffer a                        :: "A4yy
paste from named buffer                         :: "ap

paste                                           :: p P
single char                                     :: x r

search                                          :: / ? n N
line-matches-regex                              :: g/pattern/p
line-non-matches-regex                          :: g!/pattern
replace once                                    :: s/old/new
emit another replace in command mode            :: &
replace all occurs in line                      :: s/old/new/g
replace all occurs in file                      :: %s/old/new/g    (% stands for all lines, like 1,% prefix to s command 1,%s/old/new/g)
replace with confirm                            :: s/old/new/gc
only do replace in line matches patterns        :: :g/pattern/s/old/new/g
add () to lines                                 :: :%s/.*/(&)/              (& stands for whole match line)
replace with regex                              :: :%s/\(this\) or \(that\)/\2 or \1/g
replace Fortran to FORTRAN                      :: %s/Fortran/\U&/      (also has \L for lowercase)

save buffer before replace                      :: :w
revert buffer to last saved state               :: e!

edit another file foo                           :: :e foo
switch files in vi                              :: :n :rewind :last

line info                                       :: ctrl+G

append to word end                              :: ea
delete to file end                              :: dG
change to line end                              :: c$ C
goto line 100                                   :: 100G
toggle line number                              :: :set nu  :set nonu

split window                                    :: :split :vsplit
move between windows                            :: ^wj ^wk ^wh ^wl


[emacs] copy until char (like zap-to-char)


Today, When we doing a story with a piece of XML like this:


I feel not convenient to copy out the S-123456789

So I wrote a new copy-without-selection function copy-to-char function (like zap-to-char):
(defun copy-to-char (arg char)
  "Copy until char like zap-to-char"
  (interactive "p\ncZap to char: ")
  (let ((start (point)))
      (copy-region-as-kill start (progn
                         (search-forward (char-to-string char) nil nil arg)
(global-set-key (kbd "C-c c") 'copy-to-char) 


reading notes of Programming Ruby 2nd

#!/usr/bin/ruby -w
# -*- coding: utf-8 -*-
animals = %w{ant bee cat dog elk}
def say_hello (name)
  "Hello, #{name.capitalize}"

puts say_hello('ww')

$globalV = "hello"
@instanceV = "instanceV"
@@classV = "ww"
puts "#$globalV, #@instanceV #@@classV"

hash_example = {
  'a' => 'A',
  'b' => 'B',
  'c' => 'C'
puts hash_example['c']

hash_default_value_zero = Hash.new(0)
puts hash_default_value_zero['key-do-not-exists'] == 0

testflag = true
puts "use simple if statement, if possible" if testflag

puts "regex demo: if perl match /perl|python/" if "perl" =~ /perl|python/

aline = 'Perl and Python'
aline.sub(/Perl/, 'Ruby') # replace first 'Perl' with 'Ruby' 
aline.gsub(/Python/, 'Ruby') # replace every 'Python' with 'Ruby'
aline.gsub(/Perl|Python/, 'Ruby')

animals.each { |animal| puts animal }
5.times { print "*" }
3.upto(6) {|i| print i }
('a'..'e').each {|char| print char }

class Song
  attr_reader :name, :artist, :duration, :attr_foo
  attr_writer :name, :artist, :duration
  protected :attr_foo

  def initialize(name, artist, duration)
    @name = name
    @artist = artist
    @duration = duration
  def to_s
    "Song: #@name, #@artist, #@duration "

class SubSong < Song
  def initialize(name, artist, duration, lyrics)
    super(name, artist, duration)
    @lyrics = lyrics

  def SubSong.staticMethod
    "static method"

  def [] (seconds)  #index method, e.g: SubSong[22]

  def play

  def pause

  def inspect
    '#' * 10

s = SubSong.new("a", "b", "c", "lyrics")
puts s.duration
puts s.name
puts SubSong.staticMethod

class SingletonLogger
  private_class_method :new
  @@logger = nil
  def SingletonLogger.get_instance
    @@logger = new unless @@logger

  def self.static_method_form_b
  class << self
    def static_method_form_c

  def public_method_a
  public :public_method_a

    def protected_method_a
    def private_method_a

i = SingletonLogger.get_instance
puts i.object_id == SingletonLogger.get_instance.object_id
puts i.class
j = i.dup   #duplicate a new object
puts j.class
j.freeze    #freeze an object

array = Array.new
array[0] = "xxx"
array[1] = "yyy"
array[2] = "zzz"
puts array[0,2]
puts array[100] == nil

#a=[1,3,5,7,9]    → [1,3,5,7,9]                        
#a[2, 2] = ’cat’   → [1, 3, "cat", 9]                   
#a[2, 0] = ’dog’   → [1, 3, "dog", "cat", 9]            
#a[1,1]=[9,8,7]   → [1,9,8,7,"dog","cat",9]            
#a[0..3] = []     → ["dog", "cat", 9]                  
#a[5..6] = 99, 98 → ["dog", "cat", 9, nil, nil, 99, 98]

require 'test/unit'
class TestSong < Test::Unit::TestCase
  def test_method
    h = { 'a' => 'A', 'b' => 'B', 'c' => 'C'}
    assert_equal(h['c'], 'C')

def two_times

two_times { puts "Hello"}

a = [1, 'cat', 3.14]   #array with three elements
a[2] = nil
puts a.find {|element| element == 1}
puts [1,3,5,7,9].find{|v|v*v>30}
puts [1,3,5,7,9].each {|i| puts i}
puts ['S', 'V'].collect {|x| x.succ}
puts defined?(not_defined_variable) == nil

puts [1,2,3,4].inject {|p, e| p*e}

class File
  def File.with_file_open(*args)
    result = f = File.open(*args)
    if block_given?
      result = yield f

song = SubSong.new("a", "b", "c", "d")
p s
class SongButton
  def initialize(label, &action)
    @label = label
    @action = action

  def button_pressed

start_button = SongButton.new("Start") { song.start }

def n_times(thing)
  return lambda { |n| thing *n }

proc_3_times = n_times("hello")
puts proc_3_times.call(3)

num = 81
5.times do 
  puts "#{num.class}: #{num}"
  num *= num

99.downto(96) { |i| print i, " " }
50.step(80,5) { |i| print i, " " }

puts "#{'hello ' * 3}"
puts "now is #{
def the(a)
  'the ' + a
} for all.."

p (1..10).to_a
p ('bar'..'bat').to_a

digits = 0..9
puts digits.include?(5)

puts 1 <=> 2
puts 1 <=> 1

puts (1..10) === 5
puts (1..10) === 12

#102 More about methods
#method name instance_of? chop chop! name=

def method_without_parameters_do_not_need_parenthesis
puts ' '

def method_parameter_can_have_default_value(input="hello")
puts input

def varargs(arg1, *rest)
  "Got #{arg1} and #{rest.join(', ')}"

puts varargs("first variable", "and", "more", "params")

#if block_given?

#if omit the receiver, it defaults to self.
#self.frozen?  is same as frozen?
#self.id       is same as id

module Module_Can_do_mixin
  PI = 3.14
  def morsecode

module Debug
  def who_am_i

class Photo
  include Debug

require 'open-uri'
open('http://www.sina.com.cn') do |f|
  puts f.read.scan(/<img src="(.*?)"/m).uniq

#Threads and Processes
#P377 to be continue...


copy to end of line from current point

As an Emacs user, maybe you already known CopyWithoutSelection

But currently without copy to line end from current point.
Following is the my implementation, and bind to the shortcut "C-c e"


(defun copy-to-line-end (&optional arg)
  "Save point to current line end into Kill-Ring without mark (or kill and yank)"
  (interactive "P")
  (let ((start (point)))
      (copy-region-as-kill start (point))
(global-set-key (kbd "C-c e") 'copy-to-line-end)


Using Jenkins' Script Console to Download Files


* Using Jenkins Script Console to Download Files
ServerA has a file test.t want to copy to ServerB, But don't have login user on ServerB.

And ServerB running a Jenkins server, we can access.

On ServerA:
    1. goto folder of test.t
    2. execute python -m SimpleHTTPServer
       19:41 ~ $ python -m SimpleHTTPServer
       Serving HTTP on port 8000 ...

On Jenkins::
    1. execute following code in Jenkins's Script Console.
String cmd ="curl <ip_of_server_A>:8000/test.t -o test.t";
Runtime run = Runtime.getRuntime();
Process pr = run.exec(cmd);
BufferedReader buf = new BufferedReader(new InputStreamReader(pr.getInputStream()));
String line = "";
while ((line=buf.readLine())!=null) {
        println line;
Then, test.t will located in Home folder of user who running the Jenkins.

   2. Surely,  any Groovy Script can execute here.


handy commands for development


Watch something to happen                                  :: $ watch -d -n 0.1 "ls"
Find all handle of App                                     :: $ lsof -p <pid>
Find files opened by App                                   :: $ lsof -f -p <pid> 
Find which App is using specified socket port 8080         :: $ lsof -i :8080
Monitor file changes                                       :: $ lsof -f -p <pid>
Grep except something                                      :: $ grep -v string_to_except <fileName>
Monitor CPU balance                                        :: $ cat /proc/interrupts
Monitor system performance                                 :: $ nmon
Using python to start a HTTP Server to share files         :: $ python -m SimpleHTTPServer
call command with ! followed by first letter of recent cmd :: $ !<first-letter-of-recent-cmd>
pushd and popd to navigation in dir                        :: $ pushd <target-dir>
- console::
  Ctrl + u            Erase the current line.
  Ctrl + k            Delete the line from the position of the cursor to the end of the line.
  Ctrl + w            Delete the word before the cursor.
  Ctrl + r            incremental search previously called commands, continue type Ctrl+ r to search next
  Ctrl + a            Move to line beginning
  Ctrl + e            Move to line end
  Ctrl + d            Delete char under cursor
  Ctrl + _            Undo
  ESC b               Move backward one word
  ESC f               Move forward one word
  ESC d               Delete word right
  ESC backspace       Delete word left

let mysql log the queries:: 
mysql -uroot -pYOUR-PASSWORD -e "SET GLOBAL log_output = 'FILE'; Set GLOBAL general_log_file = '/tmp/mysql.log'; SET GLOBAL general_log = 'ON';"

mac os::
- To move files in Finder first press Command+C to copy the selected files, then press Command+Option+V to move the copied files to the current folder.
- ctrl+F2 to focus on menu bar
- command+shift+/ activate Help and search menu items with name
- pbcopy
- pbpaste
- Quicksilver open directory in iTerm
- cmd+D split iTerm window



Favorite emacs key-bindings

(global-set-key "\M-n"  'next-buffer)
(global-set-key "\M-p"  'previous-buffer)
(global-set-key (kbd "C-c w") (quote copy-word))
(global-set-key (kbd "C-c l") (quote copy-line))
(global-set-key (kbd "C-c p") (quote copy-paragraph))
(global-set-key (kbd "C-c s") (quote thing-copy-string-to-mark))
(global-set-key (kbd "C-c a") (quote thing-copy-parenthesis-to-mark))

(global-set-key "\C-o"  'other-window)
(global-set-key "\M-o"  'other-window)

(defvar my-keys-minor-mode-map (make-keymap) "my-keys-minor-mode keymap.")
(define-key my-keys-minor-mode-map (kbd "C-,") 'beginning-of-buffer)
(define-key my-keys-minor-mode-map (kbd "C-.") 'end-of-buffer)
(define-minor-mode my-keys-minor-mode
  "A minor mode so that my key settings override annoying major modes."
  t " my-keys" 'my-keys-minor-mode-map)
(my-keys-minor-mode 1)
(global-set-key (kbd "C-M-'") 'er/expand-region)
(define-key global-map (kbd "C-c SPC") 'ace-jump-mode)
(define-key global-map (kbd "C-;") 'ace-jump-char-mode)
(define-key global-map (kbd "C-'") 'ace-jump-line-mode)
(require 'mark-more-like-this)
(global-set-key (kbd "C-<") 'mark-previous-like-this)
(key-chord-define-global "zz" 'mark-previous-like-this)
(global-set-key (kbd "C->") 'mark-next-like-this)
(key-chord-define-global "??" 'mark-next-like-this)
(global-set-key (kbd "C-M-m") 'mark-more-like-this) 
(global-set-key (kbd "C-*") 'mark-all-like-this)
(key-chord-define-global ",," 'mark-all-like-this)
(key-chord-define-global "zk" 'zap-to-char)
(key-chord-define-global ";w" 'kill-region)
(defun append-kill-line (&optional arg)
  "Append kill-line to current kill buffer, prefix arg kills from beginning of line."
  (interactive "P")
  (kill-line arg)
(define-key global-map "\C-x\C-m" 'append-kill-line)

More on github.


mongodb-mapreduce and highcharts

During company's hackday, we analyze some bigdata in mongodb. We want to find out whether XXXXX price's short term and long term Moving averages can predicting the future price changing trends. BACKGROUND: http://www.hardrightedge.com/tactics/indicators/movingaverages.htm http://winninginvestor.quickanddirtytips.com/The-Top-5-Chart.aspx
m = function () {
    if (this.landsize > 0) {
        seq_key = NumberInt(this.seq / 100);
       if (this.valuation_range_high > 0 && this.valuation_range_low > 0) {
            emit(seq_key, {seq:seq_key, avg_price:0, price:(this.valuation_range_high + this.valuation_range_low) / this.landsize, count:1});

r = function (key, values) {
    r = {seq:key, avg_price:0, price:0, count:0};
    values.forEach(function (v) {r.price += v.price;r.count += v.count;});
    return r;
function finalizef(key, value) {
    if (value.count > 0) {
        value.avg_price = value.price / value.count / 2;
    return value;

s = db.rpdata.mapReduce(m, r, {finalize:finalizef, out : "price"})

 "result" : "price",
 "timeMillis" : 730604,
 "counts" : {
  "input" : 19477443,
  "emit" : 7345947,
  "reduce" : 26799,
  "output" : 19468
 "ok" : 1,
from pymongo import Connection
import pymongo


    def get_price_from_db(self):
        connection = Connection()
        db = connection.bigdata
        price_records = db.price

        avg_prices = []
        for record in price_records.find():
        mean_value = mean(avg_prices)
        std_value = std(avg_prices)

        normalized_prices = []
        for price in avg_prices:
            //using z-score to strip strange values
            if abs((price - mean_value) / std_value) < 1.0 :
Code on github


Enhance htmlize.el , now can export org-link.

Several Days ago, I found a problem when write blog using org-mode.
The 'html-region command in htmlize.el, just generate a CSS style for org-link,  not a real link.

So I went to great stackoverflow.com:

  1. I using great htmlize.el to export my org-mode buffer contents with font hi-lock.
  2. Emacs org-mode has a Link format.
For Example, here is a org-mode file with contents:
When I Using Htmlize.el to htmlize buffer to HTML contents, The link was missing. produces HTML like:
<span style="hyperlinkFOOBAR">blog</span>
I expected it produces clickable link like:
<a style="hyperlinkFOOBAR" href="http://hunmr.blogspot.com">blog</a>
EDIT1 The org-export-as-html can export link, but can not create CSS for the Hi-locks.
  • Do you know other ways to to export org-mode links to HTML?
  • To read the real link in org-mode buffer using elisp, how to do that? read text property?

@Andreas gave a great hint, so I tried to read the code of org-mode,
after write some elisp function, finally it worked.

The new htmlize.el was shared on github.com now:


And this the main code:

(defun expand-org-link (&optional buffer)
  "Change [[url][shortname]] to [[url] [shortname]] by adding a space between url and shortname"
  (goto-char (point-min))
  (while (re-search-forward "\\[\\[\\([^][]+\\)\\]\\(\\[\\([^][]+\\)\\]\\)?\\]"
                nil t)
    (let ((url (match-string 1))
      (link-text (match-string 3)))
      (delete-region (match-beginning 0) (match-end 0))
      (insert "[[" url "] [" link-text "]]"))))

(defun shrink-org-link (&optional buffer)
  "Change [[url] [shortname]] to [[url][shortname]], remove the space between url and shortname"
  (goto-char (point-min))
  (while (re-search-forward "\\[\\[\\([^][]+\\)\\] \\(\\[\\([^][]+\\)\\]\\)?\\]"
                nil t)
    (let ((url (match-string 1))
      (link-text (match-string 3)))
      (delete-region (match-beginning 0) (match-end 0))
      (insert "[[" url "][" link-text "]]"))))

(defun transform-org-link ()
  "transform htmlized  to "
  (goto-char (point-min))
  (while (re-search-forward "\\[\\[]+\\)>\\([^][]+\\)\\] \\[\\([^][]+\\)\\]\\]"
                nil t)
    (let ((style (match-string 1))
          (url (match-string 2))
      (link-text (match-string 3)))
      (delete-region (match-beginning 0) (match-end 0))
      (insert "" link-text ""))))


Java Performance Tuning

performance_tunning.org -->
* What I found in Performance Tuning
- "we need more CPU core. we need more memory, currently 96G is not enough on our server. we need SSD"

- using Array instead of HashMap
  || - ASN.1 parse
  || - There is a system, Every component has a uuid, but that's NOT efficient to dispatch calls.
  ||   So we assigned each component a numeric ID for fast dispatch.

- StringBuilder
- HashMap && ConcurrentHashMap && ArrayList ...

- YOUNG & OLD generation's size

+ GC in JAVA

 GC for Eden Space:

GC for Old Generation:


+ HotSpot VM options: 
    -Xms256m -Xmx512m   ||Set initial and maximum to equal, to avoid using CPU cycle to grow heap size.
    -XX:NewRatio=n //Ratio of new/old generation sizes. The default value is 2.  
    -XX:SurvivorRatio=n //Ratio of eden/survivor spacesize. The default value is 8.  
    -XX:PermSize -XX:MaxPermSize


+ If most of the application's data are short lived, you should expand size of YOUNG generation.
    otherwise, expand the size of OLD generation.
    find more GC options of HotSpot VM

+ About java GC GC Collectors

+ SoftReference, WeakReference
  + Use case of PhantomReference
  + Apple has a new Compile-time tech to avoid performance problem caused by GC: Automatic Reference Counting

- String's memory structure in JVM
  - structure of Object in JVM
    + a normal object requires 8 bytes of "housekeeping" space;
        OpenJDK6: src/hotspot/src/share/vm/oops/markOop.hpp
        //  32 bits:
        //  --------
        //             hash:25 ------------>| age:4    biased_lock:1 lock:2 (normal object)
        //             JavaThread*:23 epoch:2 age:4    biased_lock:1 lock:2 (biased object)
        //             size:32 ------------------------------------------>| (CMS free block)
        //             PromotedObject*:29 ---------->| promo_bits:3 ----->| (CMS promoted object)
    + arrays require 12 bytes (the same as a normal object, plus 4 bytes for the array length).

- structure of String Object
    public final class String
    8        |String's object header
    4        |private final java.lang.Object value;--------->,
    4        |private final int offset;                      |
    4        |private final int count;                       |
    4        |private int hash;                              |
    8        |Char Array's object header  |<-----------------'   
    4        |array length                |
    N*2      |bytes of N characters       |
    P        |bytes of padding to 8n      |
    so, empty string will using 40 bytes.    
    In 64bits JVM, Object header will use 16bytes. 

    ||Using AnsiString, with byte[] rather than char[]

- string's substring implementation 
    ||why we need create a new String after substring.  //new String(str.substring(5, 4));

  - StringBuilder/StringBuffer use less memory. 
  - ||If not concern string contents in computation and caching, you can create your own String 
    || constant pool(HashMap) to convert frequently used String to Integer value.
    || when the string is never use anymore, convert it back.

- memory compress
  - snapp-java
  - Out of heap memory #find more
  - BigMemory

- Story about not use AtomicInteger - has better performance than synchronize adding (interlockedincrement __sync_fetch_and_add) - use more memory - IN THAT STORY: can be avoided through hash re-Dispatch - AtomicReference Java volatile reference vs. AtomicReference ( compareAndSet() used in Queue implementation)

*** jps  use jps to find correct jvm process Id

C:\Documents and Settings\Administrator>jps -lmVv
   3672 org.nasa.marsrovers.Main -agentlib:jdwp=transport=dt_socket,suspend=y,address=localhost:4176 -Dfile.encoding=UTF-8 -Xbootclasspath:C:\Program Files\Java\jre6\lib\resources.jar;C:\Program Files\Java\jre6\lib\rt.jar;C:\Program Files\Java\jre6\lib\jsse.jar;C:\Program Files\Java\jre6\lib\jce.jar;C:\Program Files\Java\jre6\lib\charsets.jar
   3380 sun.tools.jps.Jps -lmVv -Denv.class.path=.;C:\Program Files\Java\jdk1.6.0_22\jre\lib;C:\Program Files\Java\jdk1.6.0_22\lib; -Dapplication.home=C:\Program Files\Java\jdk1.6.0_22 -Xms8m
   552  -Dosgi.requiredJavaVersion=1.5 -Xms40m -Xmx384m -XX:MaxPermSize=256m

*** jstack
    ||Find out current stack trace.
    ||Thread name will show in stack trace, that's why we need set name for thread and threadPool.

    + look stack pattern find bug
       ||DeadLock in webserver
          We reproduced three days. If we grab a thread dump before restart server,
          This bug will be super easy to find. same as .NET and C++.
          before restart server, first thing we need to do is collect more
           information (dump, memory usage, CPU usage)

       ||HashMap infinite loop

       ||Most thread blocked on LOG message queue's put()

 $ jstack -l 3672
2012-08-12 22:48:17
        Full thread dump Java HotSpot(TM) Client VM (17.1-b03 mixed mode):
        "Low Memory Detector" daemon prio=6 tid=0x16bb2800 nid=0x1314 runnable [0x00000000]
           java.lang.Thread.State: RUNNABLE
           Locked ownable synchronizers:
         - None
        "CompilerThread0" daemon prio=10 tid=0x16baf400 nid=0xbd4 waiting on condition [0x00000000]
           java.lang.Thread.State: RUNNABLE
           Locked ownable synchronizers:
         - None
        "JDWP Command Reader" daemon prio=6 tid=0x16bad000 nid=0xdc4 runnable [0x00000000]
           java.lang.Thread.State: RUNNABLE
           Locked ownable synchronizers:
         - None
        "JDWP Event Helper Thread" daemon prio=6 tid=0x16bab000 nid=0x16c8 runnable [0x00000000]
           java.lang.Thread.State: RUNNABLE
           Locked ownable synchronizers:
         - None
        "JDWP Transport Listener: dt_socket" daemon prio=6 tid=0x16ba8c00 nid=0x11d4 runnable [0x00000000]
           java.lang.Thread.State: RUNNABLE
           Locked ownable synchronizers:
         - None
        "Attach Listener" daemon prio=10 tid=0x16b99000 nid=0x168c waiting on condition [0x00000000]
           java.lang.Thread.State: RUNNABLE
           Locked ownable synchronizers:
         - None
        "Signal Dispatcher" daemon prio=10 tid=0x16bb3400 nid=0x1320 runnable [0x00000000]
           java.lang.Thread.State: RUNNABLE
           Locked ownable synchronizers:
         - None
        "Finalizer" daemon prio=8 tid=0x16b85000 nid=0x1678 in Object.wait() [0x16cff000]
           java.lang.Thread.State: WAITING (on object monitor)
         at java.lang.Object.wait(Native Method)
         - waiting on <0x029d0b28> (a java.lang.ref.ReferenceQueue$Lock)
         at java.lang.ref.ReferenceQueue.remove(Unknown Source)
         - locked <0x029d0b28> (a java.lang.ref.ReferenceQueue$Lock)
         at java.lang.ref.ReferenceQueue.remove(Unknown Source)
         at java.lang.ref.Finalizer$FinalizerThread.run(Unknown Source)
           Locked ownable synchronizers:
         - None
        "Reference Handler" daemon prio=10 tid=0x16b83c00 nid=0x13ec in Object.wait() [0x16caf000]
           java.lang.Thread.State: WAITING (on object monitor)
         at java.lang.Object.wait(Native Method)
         - waiting on <0x029d0a28> (a java.lang.ref.Reference$Lock)
         at java.lang.Object.wait(Object.java:485)
         at java.lang.ref.Reference$ReferenceHandler.run(Unknown Source)
         - locked <0x029d0a28> (a java.lang.ref.Reference$Lock)
           Locked ownable synchronizers:
         - None
        "main" prio=6 tid=0x00847000 nid=0x1464 runnable [0x0091f000]
           java.lang.Thread.State: RUNNABLE
         at java.io.FileInputStream.readBytes(Native Method)
         at java.io.FileInputStream.read(Unknown Source)
         at java.io.BufferedInputStream.read1(Unknown Source)
         at java.io.BufferedInputStream.read(Unknown Source)
         - locked <0x029e19f0> (a java.io.BufferedInputStream)
         at sun.nio.cs.StreamDecoder.readBytes(Unknown Source)
         at sun.nio.cs.StreamDecoder.implRead(Unknown Source)
         at sun.nio.cs.StreamDecoder.read(Unknown Source)
         - locked <0x02b63a00> (a java.io.InputStreamReader)
         at java.io.InputStreamReader.read(Unknown Source)
         at java.io.BufferedReader.fill(Unknown Source)
         at java.io.BufferedReader.readLine(Unknown Source)
         - locked <0x02b63a00> (a java.io.InputStreamReader)
         at java.io.BufferedReader.readLine(Unknown Source)
         at org.nasa.marsrovers.simulator.Simulator.startUp(Simulator.java:53)
         at org.nasa.marsrovers.Main.main(Main.java:50)
           Locked ownable synchronizers:
         - None
        "VM Thread" prio=10 tid=0x16b81400 nid=0xef0 runnable 
        "VM Periodic Task Thread" prio=10 tid=0x16bc9000 nid=0x304 waiting on condition 
        JNI global references: 1508

*** jmap
**** show memory usage 08:57 ~ $ jmap -heap 623
Attaching to process ID 623, please wait...
        Debugger attached successfully.
        Server compiler detected.
        JVM version is 20.6-b01-414
        using parallel threads in the new generation.
        using thread-local object allocation.
        Concurrent Mark-Sweep GC
        Heap Configuration:
           MinHeapFreeRatio = 40
           MaxHeapFreeRatio = 70
           MaxHeapSize      = 838860800 (800.0MB)
           NewSize          = 21757952 (20.75MB)
           MaxNewSize       = 174456832 (166.375MB)
           OldSize          = 65404928 (62.375MB)
           NewRatio         = 7
           SurvivorRatio    = 8
           PermSize         = 21757952 (20.75MB)
           MaxPermSize      = 367001600 (350.0MB)
        Heap Usage:
        New Generation (Eden + 1 Survivor Space):
           capacity = 19595264 (18.6875MB)
           used     = 16274240 (15.52032470703125MB)
           free     = 3321024 (3.16717529296875MB)
           83.0519047867893% used
        Eden Space:
           capacity = 17432576 (16.625MB)
           used     = 15573992 (14.852516174316406MB)
           free     = 1858584 (1.7724838256835938MB)
           89.33844315378289% used
        From Space:
           capacity = 2162688 (2.0625MB)
           used     = 700248 (0.6678085327148438MB)
           free     = 1462440 (1.3946914672851562MB)
           32.37859552556818% used
        To Space:
           capacity = 2162688 (2.0625MB)
           used     = 0 (0.0MB)
           free     = 2162688 (2.0625MB)
           0.0% used
        concurrent mark-sweep generation:
           capacity = 154337280 (147.1875MB)
           used     = 120364648 (114.7886734008789MB)
           free     = 33972632 (32.398826599121094MB)
           77.98805836153132% used
        Perm Generation:
           capacity = 176562176 (168.3828125MB)
           used     = 134844944 (128.59815979003906MB)
           free     = 41717232 (39.78465270996094MB)
           76.37249781062961% used

**** show memory usage according object type
        09:02 ~ $ jmap -histo 623 | head -n 20
num     #instances         #bytes  class name
           1:         57975       34551008  [B
           2:        304951       33637464  [C
           3:        166951       23748152  <constMethodKlass>
           4:        166951       22721672  <methodKlass>
           5:         21247       21762832  <constantPoolKlass>
           6:        279214       18444400  <symbolKlass>
           7:         21247       17749960  <instanceKlassKlass>
           8:         20092       13129152  <constantPoolCacheKlass>
           9:        304840        9754880  java.lang.String
          10:         53366        4497624  [Ljava.lang.Object;
          11:         15038        4360504  [I
          12:        122304        3913728  java.util.HashMap$Entry
          13:         22426        2332304  java.lang.Class
          14:          4146        2094728  <methodDataKlass>
          15:         32534        1717344  [S
          16:         12637        1676168  [Ljava.util.HashMap$Entry;
          17:         35117        1544960  [[I

**** get a JVM heap dump
        $ jmap -dump:file=/tmp/demo.map 91440
        Dumping heap to /private/tmp/demo.map ...
        Heap dump file created
      -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=C:/temp/oom.hprof

**** analyze heap dump
     +   $ jhat /private/tmp/demo.map 
        Reading from /private/tmp/demo.map...
        Started HTTP server on port 7000

+  Like !dumpheap -type Exception in windbg+sos, you can use OQL to find out 
        more useful stuff in the dumped heap, like:
select file.path.toString() from java.io.File file
**** using eclipse MAT http://www.eclipse.org/mat to analyze the dump file. 
- articles about MAT

**** Monitor GC status of JVM
  - jstat

     $ jstat -gcutil 21891 250 7
     S0     S1     E      O      P     YGC    YGCT    FGC    FGCT     GCT
    12.44   0.00  27.20   9.49  96.70    78    0.176     5    0.495    0.672
    12.44   0.00  62.16   9.49  96.70    78    0.176     5    0.495    0.672
    12.44   0.00  83.97   9.49  96.70    78    0.176     5    0.495    0.672
     0.00   7.74   0.00   9.51  96.70    79    0.177     5    0.495    0.673
     0.00   7.74  23.37   9.51  96.70    79    0.177     5    0.495    0.673
     0.00   7.74  43.82   9.51  96.70    79    0.177     5    0.495    0.673
     0.00   7.74  58.11   9.51  96.71    79    0.177     5    0.495    0.673

- visualVM

    When CPU high, can use visualVM find out the most long run method.
    When CPU low, can get some stack sample, see where is the block point.
    queue.put? queue.take? 

  - nmon  great tool to monitor CPU, memory, network, disks...

  aim:     write business calculation/logic to script
  problem: java call Groovy/Python was so slow.

  - write business calculation/logic to file XXX.java, then compile and load use customized class loader.
  - can reload java class, after business calculation/logic changed, without restart Java instance.
  - use script to trace data

  - ||CPU balance for network interfaces.  
    For some machine with multi CPU, if not properly configured, 
    all network interfaces' interrupts will goto CPU0 (like following show). 
    Then network performance will be restricted by power of CPU0.  see here for the solution.

      $ cat /proc/interrupts
              CPU0       CPU1       CPU2       CPU3
     65:      20041      0          0          0      IR-PCI-MSI-edge  eth0-tx-0
     66:      20232      0          0          0      IR-PCI-MSI-edge  eth0-tx-1
     67:      20105      0          0          0      IR-PCI-MSI-edge  eth0-tx-2
     68:      20423      0          0          0      IR-PCI-MSI-edge  eth0-tx-3
     69:      21036      0          0          0      IR-PCI-MSI-edge  eth0-rx-0
     70:      20201      0          0          0      IR-PCI-MSI-edge  eth0-rx-1
     71:      20587      0          0          0      IR-PCI-MSI-edge  eth0-rx-2
     72:      20853      0          0          0      IR-PCI-MSI-edge  eth0-rx-3

- set_thread_affinity
    ||If your system's performance is not stable, you can try set_thread_affinity.
    Restricting a process to run on a single CPU also avoids the performance cost 
    caused by the cache invalidation that occurs when a process ceases to execute
    on one CPU and then recommences execution on a different CPU.
int sched_setaffinity(pid_t pid,size_t cpusetsize,cpu_set_t *mask);
- send several packages in a Big package. - pfring - Google Protocol Buffer

*** thread local storage to prevent new objects
JAVA: ThreadLocal
    gcc: __thread int i;

 - use array if possible
 - use hash dispatch to avoid locking
 - log sampling, if log is not important, then use queue.offer()
 - keep thread count low. 
 - use message loop instead of timers
 - less exception
 - double buffer queue