TCP Socket Implementation On Golang

Golang is surely my first to go language to write web application, it hides many details but still gives a lot of flexibility. Recently I did strace to an http service app, actually did it without a reason but I found something interesting.

Here’s what strace -c gave me :

% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 91.24    0.397615         336      1185        29 futex
  4.13    0.018009           3      7115           clock_gettime
  2.92    0.012735          19       654           epoll_wait
  1.31    0.005701           6       911           write
  0.20    0.000878           3       335           epoll_ctl
  0.12    0.000525           1       915       457 read
  0.02    0.000106           2        59           select
  0.01    0.000059           0       170           close
  0.01    0.000053           0       791           setsockopt
  0.01    0.000035           0       158           getpeername
  0.01    0.000034           0       170           socket
  0.01    0.000029           0       160           getsockname
  0.01    0.000026           0       159           getsockopt
  0.00    0.000000           0         7           sched_yield
  0.00    0.000000           0       166       166 connect
  0.00    0.000000           0         3         1 accept4
------ ----------- ----------- --------- --------- ----------------
100.00    0.435805                 12958       653 total

There are a lot of interesting things in that profiling result, but the highlight of this article are the error number of read and the number of futex call

At the first sight I didn’t think about futex call, which most of them are a wake call. I thought that this app serve hundreds req per second, it should has many go routine; At the other hand it also leverage channel, it should has many under the hood blocking mechanism. So a lot of futex call should be normal, later I found out that this number was also from other things -will back to it later-. Continue reading

Optimizing Index time on elasticsearch

No replica when full indexing

By disabling replica I found the indexing time could be cut more then half the total time. Replica could be added back after full indexing completes.

Make refresh time a bit longer

Refreshing index time using default value (1 second) put quite pressure to io, especially if you indexing quite big data and querying the cluster at the same time. Making the refresh time longer could relief that io bottleneck.

Thought on Visual Studio Code for C++

I was thrilled when Microsoft announced their own open source code editor based on web technology, first thing I had on my mind was intellisense on my Linux box. Now after using it for a while, I have mixed feeling about it but mostly positive.
I have to explain my background, so you can understand my personal bias. I use visual studio for my day to day job handling thousands lines of c++ code, you can count me as happy user of it. Also for my scripting needs (lua, python, batch) I use Notepad++. For years QtCreator is my first to go C++ IDE in my linux, and I hoped Visual Studio Code could replace it.
Visual Studio Code comes with all things you can expect from modern text editor, quick command, keyboard navigation, git integration, code completion, extension repository, etc. It has broad language support with typescript and C# as first class citizen, C++ only gets sintax coloring and bracket matching. Continue reading

Compiling Cocos2DX in Ubuntu Linux

Cocos2DX is one of most popular game engine in the world and it supports almost all popular platform available. Here is how we can compile cocos on Ubuntu Linux.

  1. Compiling Cocos2DX in ubuntu linux
    Download cocos from http://cocos2d-x.org
  2. Prepare dependencies :
    libx11-dev
    libxmu-dev
    libglu1-mesa-dev
    libgl2ps-dev
    libxi-dev
    g++-4.9
    libzip-dev
    libpng12-dev
    libcurl4-gnutls-dev
    libfontconfig1-dev
    libsqlite3-dev
    libglew-dev
    libssl-dev
    glfw3

    Go to /build directory inside cocos package
    run :

    sudo ./install-deps-linux.sh
  3. Create makefile
    mkdir lxbuild
    cd lxbuild
    cmake ../
  4. compile
    make

Now you can check lxbuild directory for some compiled library.