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Book Review - The Phoenix Project

Here at Skybox Labs, we do regular lunch and learn session where a fellow colleague present on topics ranging from clean code, continuous integration, game development, machine learning to almost any areas where there are reasonable interests.

One of the very recent lunch and learn series that I have attended was focusing on DevOps which got me interested to learn more about the topic. I was looking for recommended books and the lead presenter highly recommended that I start with 'The Phoenix Project' by Gene Kim

Being inspired by the stellar reviews in Amazon, I have decided to get a copy and read it over the weekend.
A fantastic book that contains a wealth of information and delivers it in an intelligent and interesting way; a story. The book successfully captures the events and struggles of most people who work in IT Operations and gives a very good explanation on why these problems exist, and how you can solve them. It portrays a very effective way of thinking in applying …
Recent posts

Why using XOR might not be a good hash code implementation?

Using XOR for computing hash codes works great for most of the cases specially when order of computation does not matter. It also has the following benefits:
XOR has the best bit shuffling properties of all bit-operations and provides better distributions of hash values.It is a quick single cycle operation in most computer Order of computation does not matter. i.e. a^b = b^a However, if ordering of elements matter then it is often not a good choice.

Example
For simplicity consider you have a class with two string properties named Prop1 and Prop2 and your GetHashCode returns the xor of their hash code.

It will work fine for most of the cases except cases where same values are assigned to different properties. It will generate same hash-code i.e. collision in that case as can be seen in the below example.


However, using the modified approach as recommenced by Joshua Bloch's in Effective Java which uses prime multiplication and hash chaining provides more uniform distribution and a di…

Interesting bug - Line endings and Hash Code

I recently came across an interesting bug which emphasize how different line endings format can break your custom equality implementation if you do not carefully consider them.

Context
We have an application that periodically updates the local assets with latest updated resources. In a nutshell, it makes an web api call to get the latest set of metadata and compare them against a locally stored metadata file. If they differs then we update the locally stored metadata file and download new/updated resources.

Bug
For a particular asset, associated metadata file was always getting updated although there were no visible changes detected using the revision history.

Investigation
My obvious suspect was the code responsible for doing the equality check between local metadata and the metadata received from the Web API.

For verification, I setup a conditional break-point which will be hit when the equality returns false. After my debug hit the break-point, I looked into all the properties and fou…

SQL Performance improvement for User defined table types

Recently, I have dealt with an interesting performance issue with one of my SQL query and thought I will share the experience here.

Context:
We had a legacy stored procedure responsible for saving large amount of excel row data to our database tables. It was using  User Defined Table Types as one of the parameter to get a list of row data from excel. However, the stored procedure was taking very long time to save the large data set.

Root Cause:
After quite a bit of investigation using execution plan in SSMS, I was able to narrow down the performance issue to the following:


Joining with User defined table type was taking >90 percent of the timeA custom hash function which has been used multiple times as a join criteria was also quite expensive to compute.

After doing additional research using stack overflow, I was able to figure out that the primary reason for the poor performance doing a  JOIN on Table Valued parameters is that : it does not keep statistics and appear to the Query Op…

Creating dynamic email templates using C# and Office Outlook

It is quite common for many applications to send automated email notifications. Couple of months ago, I have worked on improving our old email template format to make it more user friendly.
In this tutorial I will walk you though regarding how I took advantage of Microsoft Outlook to quickly generate custom email template and later using the html template for building an automated custom email application using C#.

Steps:Creating Templates: Using the rich text editor support  in Outlook create a nicely formatted email. Use placeholder text for the values you like to change dynamically based on your task completion status.

To keep this tutorial simple, I have created a  simple table with placeholder text inside the third bracket [place holder text]. However, you can use anything supported by outlook editor.Getting HTML code: Send the created email to your own address. After that, open the sent email and right click to view source. It will display the HTML source of the email body with …

How to setup remote debugging on a remote machine running within a VM?

This guide will show step-by-step instructions of setting up a remote machine for remote debugging using Visual Studio 2013 Prerequisite:
Visual Studio 2013 or laterRemote machine running Windows 7 within a VM playerNote: Since Visual Studio 2012, Microsoft only supports remote debugging for Windows 7 or newer. To remote debug Windows XP, you'll need to use an older version of Visual Studio and its respective remote debugging tools.
 Step-by-step guide:Download and copy the Remote Tools in your Win7 VM.You must get the update version of the Remote Tools for Visual Studio 2013 that matches the update version of your Visual Studio installation.Install the Remote tools in your VM.After installation, run the Remote Debugger Navigate to Tools->Options MenuEnsure that Windows Authentication is selected. Press OK.Open Visual Studio in your local machine.Make sure you have setup the remote machine in the project you like to remote debug as shown in the following figure.

 You also need to u…