Adventures in Tech

I wanted to experiment with TensorFlow, and decided to do that in a Linux VM, despite the fact that Windows Subsystem for Linux exists. In the past I used Sun’s, and then Oracle’s VirtualBox to manage virtual machines, but since my Windows install had Hyper-V, I decided to use that instead. The virtual machine configuration was easy, with disk, networking, and memory configurations non-eventful. However when I tried to start the virtual machine to setup Ubuntu from an ISO, I was greeted with the following error: “Virtual machine could not be started because the hypervisor is not running” A quick Internet search revealed that a lot of people have faced that problem, and most of the community board solutions did not make any sense. The hidden gem is this technet article , which included detailed steps to find if the Windows Hypervisor was running or not, and the error message if it failed to launch. In my case, the error was: “Hyper-V launch failed; Either VMX not present or...

I watched a video interview with the 10 th heir of Twinings Tea Company, that has been merchandising tea for over 300 years. In the interview, among talking about the family history, and the story behind their bestselling tea flavor—Earl Grey—he talked about the best way to brew tea, whether using loose leaves, or a tea bag. To extract the most flavor out of tea, he recommended bringing cold water to a boil, and removing the kettle off the stove once the water starts boiling. His theory is that the flavor is extracted through the air in the water, and continuing to boil the water further, will reduce the amount of air in it. For green teas, he recommends letting the kettle set for 5 mins, then pouring the hot water over the tea, and for black teas, he recommends pouring the hot water immediately over the tea. The heir advised against removing the bag, or repeatedly dunking it in the water during brewing, because that only changes the color of the water, and makes the tea bit...

When I have the chance, I like to walk to my meetings instead of using the shuttle service available on campus. When it is not raining, the walk is very refreshing: I get to clear out my thoughts on the walk, and get in some number of steps for my daily activity.  After one of my meetings ended, I started to head back to my building, only to see that it started to down pour. To my luck, there was a shuttle parked upfront. I asked the driver if she could take me back to my building, and she said she was on her lunch break. As I said no worries, I’ll just walk back, she insisted that she can drive me. I hopped in the shuttle, thanking her profusely for taking the time from her lunch break to drive me back, she insisted it was not a big deal. Such an act of kindness made my day, and it is a great reminder to continue doing good things to others, simply for the joy it brings them.

I am a big fan of good and delicious food, irrespective of where it is sold. That includes street vendors, and “holes in the wall,” which I have always associated with small nondescript places, with no signs on the venue, no place to sit, and a staff that exudes a slightly higher risk of contracting dysentery, typhoid, or other gastrointestinal diseases. That description might be a bit extreme, but I had some of the best meals in similar places, including the famous Hyderabadi Dum-Biryani in a place not so far from that description. So where did the phrase a “hole in the wall” come from? On another historical tour of Florence, our tour guide and language enthusiast pointed out some of the palaces where Italian nobility such as the Medici family lived long time ago. Invariably at the entrance there was a slit or a hole in the wall, and the tour guide told us the story that after the nobility hosted lavish dinner parties, instead of throwing the remaining food away, they would gi...

The two-phase commit protocol is widely known in the database community, yet despite its notoriety, finding the paper that first described it proved pretty difficult. The closest find is the paper about commit protocols for distributed transactions , which describes the protocol in detail, and introduces two additional modifications. The paper references the original publications of the protocol by Gray, Lamport, and others, however I could not find these notes   online. The paper describes the 2PC protocol, both under normal operation, and when failures occur. For normal operation, when the user decides to commit a transaction, the coordinator initiates the first phase of the protocol--the prepare phase, by sending prepare messages to all its subordinates. Each subordinate that can commit the transaction, writes a prepare log record, and sends an ACK back to the coordinator. The subordinates that can't commit the transaction, write an abort log record, and   resp...

One of my favorite activities while traveling is to take a walking tour of the city I am visiting. The tour usually consists of a small group led by a tour guide, who invariably is a student of art or history studying abroad, or an expat humanities graduate who is living abroad and is augmenting their income by giving tours. The tours are always enjoyable, combining stories about the city and its history, architecture, and cultural spots with frequent stops to coffee and dessert shops. Sometimes you get a special tour guide, who in addition to being a history buff, is also a linguistics enthusiast. When that happens, you hear special stories about the historical origin of phrases: something I am very interested in. In Rome, I had such a tour guide, and the story stuck with me, although I could not verify its accuracy. I could find one website that has a similar reference to the story. It was hilarious and I remembered it to this day. It is the story of the origin of the phrase “...

The latest advances in Big Data systems have made storing and computing over large amounts of data more tractable than in the past. Users' expectations for how long a query should take to complete have not on the other hand   changed, and remain independent of the amount of data that needs to be processed. The expectation mismatch of query run time causes user frustration when iteratively exploring large data sets in search of an insight. How can we alleviate that frustration? BlinkDB offers users a way to balance result accuracy with query execution time : the users can either get quantifiably approximate answers very quickly, or they can elect to wait for a longer period of time to get more accurate results. BlinkDB accomplishes this tradeoff through the magic of dynamic sample selection, and an adaptive optimization framework. The authors start with an illustrative example of computing the average session time for all users in New York. If the table that stores users...