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


Upgrading elasticsearch 2.x to 5.x

Last year elasticsearch 5.0 released to public and 5.2 just released last month, so it should be the right time to upgrade your infrastructure to the latest version of our beloved search engine.

This article give us many insight about why we should upgrade to the latest version :

Upgrading elasticsearch is not easy task although it is not hard to make the cluster run again, especially if you use deprecated thing so make sure to simulate all things in your staging environment. Luckily the documentation is complete, so it can save your time.  Continue reading

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
  2. Prepare dependencies :

    Go to /build directory inside cocos package
    run :

    sudo ./
  3. Create makefile
    mkdir lxbuild
    cd lxbuild
    cmake ../
  4. compile

Now you can check lxbuild directory for some compiled library.

Great Terminal Emulator

My daily work before joining gameloft is mainly with linux environment and like another linux user I use terminal emulator frequently. However I must admit that there are big cons when we use terminal for daily activity, the main issue is our discover-ability of function. In GUI paradigm discover-ability is not a question, if we don’t know about a feature -we probably need- just take a look at App UI and we will find something. We hardly rely to experience and search engine to know a feature we need and we haven’t known.

That’s why I’m really thrilling with , it will help us to maximize our unix terminal’s powers.