Technology – Jonathan's Ramblings

I’m using Twitter now!

2014-09-02 by Jonathan Leave a Comment

So, recently, I’ve run into a class of things I think that are way too short to put into a blog post, but I just do not feel like posting to other places. I mean, there’s Facebook, but anytime I post to Facebook I feel like I’m making way too big of a deal out of something. Then there’s snapchat, which works, but I think my snaps are pretty boring and then there is no way to remember things. Plus, it feels too targeted. To be clear, here are some examples of things that I have thought about posting the past few days:

How to ship code: 1. Change the DNS rules; 2. Upload the files; 3. Fly out of the state without a laptop #doingitright

I just wrote a letter to my sister and managed to start every paragraph with “So,” #ashamed #toolongtorewrite

Finally got my laptop back! #twoweekslater #canfinallywritethispost

Now, at first, I came up with what I thought was a pretty wonderful solution, and I’m sure it is exactly what everyone is thinking of. I was going to write a small wordpress plugin that would let me make tiny updates that would show up in a module (or whatever wordpress calls the tiny things to the side) with the last couple of them visible. It solved all my problems: I’d have a chance to do a tiny bit of wordpress development again and I would have a place to post these things. Then I realized that this really alread existed…in the form of Twitter.

So, anyways,

I realized I have a use case for Twitter and should stop being stubborn and avoiding it http://t.co/az5dlXmcaE

— Jonathan Pevarnek (@jpevarnek) September 3, 2014

Operating Systems and Food Trucks

2014-08-22 by Jonathan 2 Comments

So, I’m sure the thing everyone is wondering right now is (I mean, assuming you read the title): “What do operating systems and food trucks have to do with each other?”. My personal comprehensive list is one item long: “They are both in the title of this blog post”. I’m sure you are now wondering why I chose to put them in the title, and that’s because the rest of this post is about to cover applying the language of operating systems to working in a food truck (and by that, I mean the sausage trucks you see at fairs). Why am I choosing to talk about that? Earlier today, I was volunteering at a sausage truck with a Kiwanis club and I kept catching myself using operating system terminology or thinking about the work in terms of different concepts in the field. For those of you familiar with O/S terms, I do understand I am about to make a couple bad mappings, the goal of this post is more to talk about how the terms could be used in everyday speech (which, in my opinion, is one of the best parts of having O/S knowledge)

So, today, after a bit of shuffling around, I ended up working the pretzel station in the food truck. This entailed taking some pretzels, putting them in the microwave for a few minutes, taking them out of the microwave, covering them with salt, placing them in the display, and repeating. Here, I’ll draw a pretty ascii picture for you. My guestimates about times are included as well (some of these are very wrong by the way).

|-----0-----|-----------|-----------|-----------|-----1-----|-----------|-----------|-----------|
|  insert   | microwave |  remove   |   salt    |  insert   | microwave |  remove   |   salt    |
|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|
|   ~0:20   |   ~2:30   |   ~0:10   |   ~1:00   |   ~0:20   |   ~2:30   |   ~0:10   |   ~1:00   |
|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|

So, what you see here is a highly serial process. Each task is completed before any other task is started, and only one task is going on at any single time. What you see here is also an incredibly inefficient process and there are a lot of places to improve it. By the way, to start with, let’s say that we are making three pretzels at a time, and it’s taking about four minutes to do that (so ~1:20/pretzel).

Approaching the problem of making this more efficient from a systems perspective, the first thing we want to do is look for resource usage. Here, we can identify a couple major resources: the microwave and the salt. Here’s a nice picture of when these resources are being used at each step of the process.

|-----0-----|-----------|-----------|-----------|-----1-----|-----------|-----------|-----------|
|  insert   | microwave |  remove   |   salt    |  insert   | microwave |  remove   |   salt    |
|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|
|   ~0:20   |   ~2:30   |   ~0:10   |   ~1:00   |   ~0:20   |   ~2:30   |   ~0:10   |   ~1:00   |
| microwave | microwave | microwave |   salt    | microwave | microwave | microwave |   salt    |
|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|

Looking at this chart, it’s pretty clear that there is a big portion of the time that we are using the microwave, and a big portion of the time we are using the salt, and really not much overlap between those times. There are a couple ways we could approach this problem from an O/S perspective but I’m going to take us out of the picture, assume that everything is being controlled by a robot, and introduce a really awesome concept: pipelines!

So, the idea of a pipeline is that you have a number of resources and while each resource can only be doing on thing at a time, you can have multiple resources working at the same time. One way to think about this in the real world is doing laundry (with only one washer and dryer but with multiple loads): you can load the next load of clothing into the washer before the first load is done in the dryer. For us, this means that we can do the salting at the same time as the microwaving is happening for another batch of pretzels! A diagram of this is below, with all the microwave stuff having been condensed to one step for simplicity.

| microwave |   salt    |
            | microwave |   salt    |
                        | microwave |   salt    |

In this graph, it takes us three minutes to finish one step of the pipeline once the pipeline is in its steady state (the period after warm-up (the beginning, where only microwaving is going on) and before cool-down (the end, where only the salting is going on)) which takes us down to only one minute per pretzel!

Now, the above metaphor of pipelining is actually kind of weak, and that’s because I’m leaving out a pretty significant detail: the person. As a person, one is required to be doing work during most of these steps as well. That graph above? It actually will not work because the first twenty seconds (and last ten seconds) of the microwave step require a person to actively be working as does the entire salting process (the timing ends up still working, but only because salting takes less time). To really get a better picture of this, I’m going to talk about another cool operating systems concept: threads.

In an operating system, a thread is a way to abstract the fact that a computer processor can really only be doing one thing at a time, but we expect our computer to be doing a lot of different things at once. We would all be pretty upset if our phone completely froze up as we tried to load a website and we could not go send a snapchat at the same time. It’s a way for the computer to deal with all the waiting it has to do while doing I/O (downloading that website is mostly just waiting for the data to arrive). Internally, the computer ends up constantly switching between threads constantly so that it is “always” working on something, the same way we multi-task (except it is WAY better at threading than we are at multi-tasking). To think about preparing pretzels in terms of threading, we look at ourselves as the process and consider what thread we are going to work on (i.e. what task we are going to do). For the below, I’m going to label items in ten-second interval for what we are working on at any given time, with each new set of pretzels being on a new line. “M” is the times we are using the microwave, “S” is anything where we are using the salt dish, and “-” is anytime the food is in the microwave and we are not doing anything with it.

0     1     2     3     4     5     6     7     8
  SSSSSS
MM---------------M  SSSSSS
                  MM---------------M  SSSSSS
                                    MM---------------M
                                                      etc.

I’m going to condense this down to one line, removing the “-“s since they do not make sense at a global level.

0     1     2     3     4     5     6     7     8
MMSSSSSS         MMMSSSSSS         MMMSSSSSS         M...

Looking at this, we can see that there is a huge chunk of time that no work is being done (50% of the time actually (not on that graph, but looking at a steady state)), that’s because we are blocking on the microwave. Whenever a computer scientist says blocking (not sure about everyone else, but this is probably the term I use most often in everyday speech), it means that something is not able to get work done because some other resource is not available. In this case, we can’t start another set of pretzels because the microwave is in use. When that happens, all you really can do is wait for other work to come up. In the case of the sausage truck, I was right next to where they were grilling the sausages so I could use the time to move uncooked knackwursts into a pot of hot water. That entire process (getting a bag, opening it, separating the sausages, changing gloves since I just touched raw meat) ends up taking about a minute and a half, which gives us the following time graph:

0     1     2     3     4     5     6     7     8
MMSSSSSSKKKKKKKKKMMMSSSSSSKKKKKKKKKMMMSSSSSSKKKKKKKKKM...

As you can see, that shows 100% CPU (i.e. me) utilization, an awesome goal to reach in many cases (in computing, there are many times where you end up with very low CPU utilization because most of the time is spent waiting to read/write things to disks/the network). Thinking back to our pretzels, we still are still only turning them out at a rate of 1/minute, and I can assure you that people at a fair order at a higher rate than that. In computing, the normal way to deal with this is to throw more resources (i.e. money) at the problem, and the Kiwanians chose to do much the same thing adding another human, microwave, and salt tray at the other end of the sausage truck (in computing, we’d also refer to having multiple CPUs (people) doing the same task as adding parallelism). This brings the time per pretzel down to thirty seconds and gives you the following nice graph (yeah, I have no idea what the person at the other end of the truck was doing with the extra time).

0     1     2     3     4     5     6     7     8
MMSSSSSSKKKKKKKKKMMMSSSSSSKKKKKKKKKMMMSSSSSSKKKKKKKKKM...
MMSSSSSS?????????MMMSSSSSS?????????MMMSSSSSS?????????M...

There are a bunch of other ways you could look at this from an operating systems standpoint (many of them proving a much better mapping than what I chose to go with), as with many of the mudane tasks we do on a daily basis. Being a computer scientist gives you a lot of new ways to talk about doing work…the only downside to that is you sound like you are just speaking gibberish in many crowds.

How I use Trello for Circle K

2014-04-15 by Jonathan Leave a Comment

Well, the draft for this post has been sitting around since August of last year, so I thought I might as well publish it now. I’ve included roughly what I had saved, a few cleanups, and then a section at the end that goes over some slightly more modern thoughts I had. Eight-month-ago Jonathan knew nothing…

This summer, I have had the amazing chance to work at Fog Creek Software on a product called Trello (trello.com). To give a really quick summary, Trello is a great way of managing to do lists (or other kinds of lists), and includes a lot of nice features for working with teams. In addition to working on it, and using it for work, I have started to use it a lot more for personal things. One of the areas I am getting the most use out of Trello lately has been for Circle K. Trello has done a great job of helping me keep up-to-date with my work as a Subregion C trustee, but I honestly don’t think that is where it is the most useful. It offers a lot to help you stay useful as an individual, but can do even more for helping Circle Ks stay organized as a group.

Subregion C

I guess the best place to start talking would be about how I use Trello for Subregion C business. I have my Trello board split into a variety of lists: Communication Points, TODO, Notepad, and Transition Items. Moving from left to right, Communication Points is where I keep information on the people and groups I talk to. I have a card that just stays in the list for every person I talk to on a regular basis, and I keep the cards updated with a check-list of everything I have thought to ask the person about. When the checklist gets too long, I make sure to schedule a meeting and then leave a comment on the card about what we talked about. This helps me make sure that I am not needlessly bothering people, and also makes sure I have things to talk to people about when I get the chance, and I have a central place with notes about what we talked about. There are also notes here for things like meetings and emails, just to help me stay on top of those too. (for another perspective on what I’m trying to accomplish with this first list, see http://blog.trello.com/using-trello-for-impromptu-meetings/)

The next list is by far the most boring one, TODO. This is probably the most traditional list, I just stick cards in here, with actual due dates, for things I need to take care of. Whenever I find free time, I just look at what is at the top of that list and work on it. This list has included things such as getting bylaws from the Kiwanis staff or writing updates for board meetings. Past that list, the other two are for me just making notes. The first, Notepad, is just where I leave notes that I want to be able to refer back to. This has included things like my personal notes about what we talked about at committee meetings, to some cool ideas for service projects that I think I might want to refer back to latelr (actually, to be totally honest, that is all that is in the list). The final list, transition items, is just about the same thing, however, I’m making these notes for whoever comes after me instead of myself. Honestly, I just wanted a place I could put things I knew should be in my packet without having to be too much on top of things and start my packet.

Committees/Boards

Now, Trello is great for helping me stay organized personally, however, I think it is much more useful for working with groups of people. One place I used it in the past was for the Technology Committee in the Circle K club at the University of Michigan. The Trello board gave us a good way to organize what projects people were working on without me needing to constantly be bothering everyone (or, at least, that was the idea). For this, we kept a couple lists that were cool ideas we knew we would eventually want to work on. Once we decided that an idea was good enough (and we had the necessary time/experience), someone would pick it off of a list, and start working on it (by moving it to another list and joining the card). Finally, once a feature actually got added to the website, the card would get dragged to a list representing what was done each month, which was helpful when I was working on my MRFs. This was a great tool for me when trying to figure out what people were working on, as well as for when people (finally) finished whatever they were working on and needed something else to do.

For the tech committee, Trello fit extremely nicely (using it pretty much exactly how trello.com/dev is set up), however, this is not how most committees within the club function, or how any boards (yeah, not referring to Trello boards here oddly) function. When I joined the K-Fam committee at the beginning of the summer, I set up my own personal board to help me keep track of what I was doing. It ended up looking a lot like my board for Sub-C stuff (two columns, “Communication Points” and “TODO”), and feel free to draw ideas from that. If I was setting that up for the whole committee, I’d end up using the same idea, but there are a couple more things I’d add that do not apply to me. First, I’d add a column for weekly projects like helping out at the Kiwanis Thrift Sale, or going to meetings of the local Builders Club. These would function pretty much exactly like communication points (leaving a comment whenever you did something relative to the project), however, it would be a more specific place to look when thinking about updates for the projects. Next, since the committee handles a bunch of non-regular projects, I would make a separate list for those. There are some Circle K events (e.g. Service Day) that may be able to make use of their own separate board, however, I don’t think anything more than a card is necessary for most things.

Modern Comments

I thought I would come back and leave some comments (past the cleaning up and rewriting that I did above) based on the extra eight months of life experiences I have now.

First of all, regarding the Sub-C Trello Board, I have continuously referred to it throughout the year. That said, there were a bunch of things that I became a lot less diligent about taking care of, most notably notes from meetings. I wish I still did as good as a job with these as I did at the beginning of the year, however, laziness kind of took over and my notes became hastily scrawled on paper instead of the organized masterpieces they were before (yeah, I fail at notes in general, but they were much closer to masterpieces at the start). As far as the K-Fam stuff, UofM’s Circle K did eventually try out Trello, and I made the K-Fam board conform to pretty much exactly what I said…and no one used it. Trello is a fantastic service, however, it’s pretty much useless if no one gets on-board with it and I’m sad that there was not a stronger push towards that than what we had.

I hope that you got some good ideas about how to use Trello from this post. For me, it is a nice tool for staying organized, and I think it has the potential to help a lot more people out with that. If your Circle K is not using it already, I completely encourage you to try it, it can be a huge asset for your club, or any subset of your club.

Google Doc Email Notifications

2013-03-27 by Jonathan Leave a Comment

I don’t think I have made any posts in the past about something this simple, however, I just discovered this and I am wishing right now that I had found it sooner. In Google Docs (well, technically, Google Drive Spreadsheets) it is possible to set up email notifications for whenever a spreadsheet changes. Most impressively, this means that you are able to have an email sent to you whenever someone fills out a form! To set this up, open up the spreadsheet (the one receiving form submissions), click on “Tools” (in the menu bar), and click on “Notification Rules…”. You can select different options for how to be notified here. Personally, I think the most useful one is to be notified whenever a user submits a form. You can set this so you get the email either the moment the form is submitted or you can get a digest every day with a summary.

With this said, I was kind of disappointed when I realized that this does not extend to documents. There are a couple documents I have where I would appreciate an email when someone else updates it. Overall, however, I think form submissions are the most important action to have emails for and I wish I had known about this sooner.

Tablets

2013-01-15 by Jonathan Leave a Comment

I currently own two tablets: an iPad (third generation) and a Nexus 7. For a while, I thought that tablets seemed like a complete gimmick and did not even vaguely consider purchasing one. Since then, I have had time to think about what I want from my different devices and, most importantly, have been overpowered by the shiny devices.

When deciding to purchase the iPad, the main item that convinced me was the presence of a lot of extremely well-made aviation apps. Many of the apps for aviation (most notably Foreflight) are available only for iOS so that helped make the decision a lot easier. In addition to these apps, the iPad did bring with it a slightly added status boost and looked cool. Thinking that I could use the device for note taking as well as for aviation, I decided to buy one in October.

Since I bought the iPad, I have used it for a variety of tasks, none of which actually had to do with flying (one exception here, but ignoring it). The two main uses I have had for the iPad are reading the New York Times and using iAnnotate. The New York Times is an outstanding source of news and being able to simply grab the iPad from my nightstand and start looking at todays news the moment I wake up is very nice for me. iAnnotate is also extremely useful and has made reading pdf documents a much less painful experience as well as improving my productivity whenever I need to do so. In addition to the apps, I love the navigation that Apple built into the device (the multi-finger dragging). In spite of these great apps and the couple nice UI features, I can definitely say that the iPad was not worth its cost to me. In general, the iPad has been an excellent gadget to amuse myself with, and one that has helped me be slightly more productive. I cannot, however, say that it was worth its cost.

A few months later, becoming jealous of the Nexus 7 that was to be my mother’s Christmas present, I decided to purchase one of these tablets for myself. Primarily, I really liked the simple Google UI, Google Now, and the smaller size. Of these three, I still love the UI and Google Now, but the size has not actually affected the way I use it. Coming from a phone with motoblur, the fact that everything was simple and worked the way I would expect was refreshing. Regarding Google Now, the first time I turned the device on was as I was about to leave for the airport and it immediately pulled up my flight information along with directions to the airport and travel time. That was enough to sell me on it being useful and cool and was the main reason I became sold upon the device. Since then, I have found a lot of other cool features in Google Now, but it has become kind of useless with a tablet that does not have a constant internet connection. As far as value goes, I use the Nexus a lot less than I do the iPad, however, it also cost a lot less. If I no longer had the iPad, I think I could switch to using most of my common apps on the Nexus and still be satisfied. At $200, it is definitely worth it to get a Nexus 7 if you do not already have one, however, there is not enough of a bonus to purchase one if you already own one.

Using these two devices, I have learned a lot about how I use technology and what I expect of it. Tablets are never going to be able to fill the role of a primary device for me, however, they are a fun amusement and I am often glad I have at least one of mine. Owning two is a bit excessive for me, however, I am happy enough with each individually that I cannot imagine giving either up.

On a side note, I have had time to think about what apps I use the most while writing this and will be making a post soon about those.

rlwrap

2012-09-21 by Jonathan Leave a Comment

Working in Linux, we normally have fairly well-made shell programs to work with. Convenient libraries such as GNU readline (http://tiswww.case.edu/php/chet/readline/rltop.html) developers are able to quickly and effortlessly add command history, movement within the line, and all the other nice things we have been taught to expect. Unfortunately, some programs do not do this, something I unfortunately found I would have to deal with while using sqlplus for my databases class this semester. Fortunately, with a little help from google, I was able to find a nice wrapper program that would add the expected readline functionality to any other program! rlwrap (http://utopia.knoware.nl/~hlub/rlwrap/#rlwrap) has so far been an absolute lifesaver and I am reasonably sure it alone will be making this class bearable for me. I have no idea how it works (I will be checking the source code at some point…maybe…) so I am just going to say it uses magic to add the functionality I expect every program to have to the programs that do not have it.

Linux Coding Standard

2012-09-21 by Jonathan Leave a Comment

I have been looking at a few coding standards recently and for the most part, I am happy with the Linux kernel coding style (http://www.kernel.org/doc/Documentation/CodingStyle). It has a very nice description of how to code everything in a terse but clear way which is something a lot of other guides lack. There are two items with it though that I definitely do not agree with: the indentation for switch statements and the use of braces in if/else statements.

For switch statements, the coding style recommends having the case statements at the same indentation level as the switch statement (see below)

switch (suffix) {
case a:
	break;
default:
	break;
}

In my opinion, this is hard to read and the case statements should all be indented by another level (see below)

switch (suffix) {
	case a:
		break;
	default:
		break;
}

The style also specifies that curly braces should not be used with conditional statements unless one branch consists of multiple statements. I completely agree with this concept for a single if statement, however, I think it looks a lot cleaner to use braces if there are multiple branches in the if statement. This does not add a significant amount of white space (only a single line thanks to the inline braces), gives a cleaner separation, and prevents people from stupidly adding an extra statement they think is in a branch but really is not. The change I am proposing is below.

if (cond)
	action();
else
	other_action();

would become

if (cond) {
	action();
} else {
	other_action();
}

With these two changes (and adaptations for things like classes and other non-C language features), I will be using the Linux Kernel Coding Style as my personal coding style. There are times when I do things wrong (for example, I often do not put spaces around “*” and “/” just because my Engineering 101 professor instructed us not to) but overall this is a nice sound style guide and one I will be happy trying to follow.