Category Archives: Programming

Programming – C/C++, Java, Ksh, Python, ML

getdelays – get delay accounting information from the kernel

Posted on September 6, 2016 by

Top may be the most common tool in use whenever a preformance issue is hit. It is simple, quick and dumb. Besides the heavy metal stuffs like perf and gprof, another really useful and simple tool is getdelays, which provides … Continue reading →

Posted in OS, Programming | Tagged , , , , , | Leave a comment

Linux kernel I/O Stack Diagram

Posted on August 5, 2015 by

Found this figure online. The title of this diagram may be biased as it is not the complete I/O stack but a concentration on block devices with a focus on SCSI layer. Some important missing stuffs, in my opinion, include … Continue reading →

Posted in OS, Programming | Tagged , , | Leave a comment

Python Levenshtein distance – Choose Python package wisely

Posted on May 2, 2015 by

Brad and I were working on some text similarity computation. One of the most popular string distance functions is the Levenshtein distance, which is also called the edit distance. We use Python for its brevity and widely-library support (OK, I … Continue reading →

Posted in Programming | Tagged , , , | Leave a comment

Retrieve PID from the packet in Unix domain socket – a complete use case for recvmsg()/sendmsg()

Posted on February 17, 2015 by

The original question was how to retrieve the PID of the packet (sender) in the Unix domain socket. As titled, the answer is recvmsg()/sendmsg(). However, the most useful information I could find online is Michael’s man7.org. People keep talking about … Continue reading →

Posted in OS, Programming | Tagged , , , , , , | 1 Comment

Bash Hacking – bash2, add setting CPU affinity support to the Bash

Posted on January 29, 2015 by

This post is NOT initially designed for how to hack Bash. But it does tell the truth that hacking Bash is not that hard, by adding a useful feature to Bash itself – setting CPU affinity support. Have fun and … Continue reading →

Posted in OS, Programming | Tagged , , , , , , | 4 Comments

Python Internals – Integer object pool (PyIntObject)

Posted on December 11, 2014 by

Starting from this post, I will try to make a series of blogs on Python Internals, where Python object mechanism, Python bytecode (pyc) and Python VM are gonna be discussed. We will also talk about the limited resource online about … Continue reading →

Posted in Programming, Stuff about Compiler | Tagged , | Leave a comment

Python Hacking – urlopen timeout issue

Posted on November 14, 2014 by

Recent playing with Python urllib2 reveals an interesting fact that the timeout parameter of urlopen() does not work sometimes. The interesting issue has successfully pushed me deep into the Python source code for debugging. The final debugging, without surprise, shows … Continue reading →

Posted in Programming, Stuff about Compiler | Tagged , , , , , , | 4 Comments