How To Identify Inefficient Code Within a Function - performance

I was recently asked this question during an interview & apart from console.log & debugger, I wasn't able to give more tools / options for this problem.
The question was: I am reviewing code & I find that the code is causing performance issues. The code is one very lengthy function. How would I go about identifying the line/s of code causing the performance issues.
Thinking about it, now, post the interview, the only other solution that comes to mind is to break the code into tinier functions & analyse. However, I wonder whats the best solution to this problem, not only for the interviews, it would help me be more mindful of options available when I do encounter this problem in real life. (unfortunately, the interviewer was quite non-communicative & clearly wanted to go through the questions as quickly as possible).
Thanks

One easy way to do this is to store the current time right before the infamous function call, then in that function, store the current time before and after strategic places where you think the culprit is. At the end, print the time that it took to execute these parts that are in between the strategic places and you will have a good idea of where the system is spending much of its time.

Related

What to do when faced with a seemingly unsolvable situation with a time limit?

I am a computer sciences student and I usually have really tough programming assignments. I don't know if it is only happening to me but sometimes, particularly when deadline is approaching, I find myself in a harsh situation.
I cannot find my mistake in the code or come up with a another great idea. Then boredom comes in and the problem begins to seem unsolvable.
I would like to learn their ideas to cope with this situation. Is it better to focus on something else for a while? Or try again? Or try harder and harder and look for the solution on the net, etc?
I alway like talking about the solution with another programmer. Just talking makes me use a different part of my brain and most of the time I hear myself talk through a solution.
Sleep is good, or if not sleep then at least taking a break, going for a walk in the fresh air etc.
Brainstorming the problem with colleagues / fellow students can help. Even just explaining the issue to someone else can be enough to make the solution click in your brain.
Failing all the above, ask on Stackoverflow :-)
Try breaking down the problem into smaller, easier problems, and solve those. Don't try and tackle everything at once, and avoid trying to hack your way through.
If you're still stuck, taking a break can be good. Sometimes the answer is suddenly obvious when looking through a refreshed pair of eyes. Solutions to problems often come to me in my sleep, and I'll wake up knowing the answer.
For me, I encountered a couple of times where I took quite a bit of time (10 to 30 mins) to define the problem in writing as to submit the question on SO, and got ideas that led to the eventual solution while typing out the question.
I find that when I document your problem in a way that others can understand without having to understand the unrelated parts of the your entire application/project, I consciously break down the problem into isolated, independent parts which helps me or another developer analyze and decide the next course of action.
Just my two cents :)
In your case (school work) I would probably seek out the instructor/professor or TA. While they will certainly not "give" you the answer at the very least you might learn something else in the process.
Specifically I would explain to the the difficulty you are having, what you have done to try to solve it and any other things to show that you did work.
A lot of times while walking though this on your own you might come up with solutions. They can probably give you hints or suggestions as well.
Worst case scenario is that they tell you to go away and to leave them alone.
Others have posted sleep (#sjobe, &Vicky) and asking someone is good (#Christopher Altman). BTW, that is often referred to as "rubber-ducking".
My personal problem is wanting to see something through and getting consumed in getting to the finish, almost always to my own determent. What I've learned over the years if a little research doesn't help (< 30 minutes) and talking it through doesn't explain it and you can't or don't want to sleep on it, do something for the mind, body and spirit: Go outside!
Seriously, go for a 30-45 minute bike-ride, run, walk, swim, whatever. Try to think of something else. Tell yourself a story or mentally work on another problem if you must. Cool down and return. You'll be amazed at how refreshed you'll feel. The endorphins will help.
If you're embarking on career driving a desk, it's a great habit to get into as well.
-Cheers
The entire art of surviving or rather conquering in situations like this is about staying to have a solution oriented approach . By this I mean staying positive that even if a solution is not working it , have faith that your tries are getting you closer to it .
Yes I strongly agree that taking a break is an integral step of reaching your goals but take a break to return back with stronger spirits to solve a problem .
Involve yourself into different solution finding strategies along with a spirit to enjoy the same .
The solution finding strategies may involve :
Talking to your friends who dont understand the problem to a good level and help them understand . It will help you explore the ins and outs of the scenarios . Sometimes explaining other people helps us understand the problem in a much better scenarios .
Sit down with a paper and a pen or its better to have a diary where jot down all the ideas as they strike you . Take your diary with you always as it helps to jot down the ideas otherwise later we forget . Also sometimes the game is about connecting the dots . An idea from morning first half and evening time can be perfect mix to resolve the problem .
Go out on a brainstorming session with couple of friends and entertain all the ideas that they put on table for once and consider them . Remember no idea is an stupid idea . Either it is solution or a contributing step towards a solution .
There may be times when you need to visit an industry expert or a researcher to dig deeper into concepts of technology . Before you visit an industry expert keep all your research documents and brainstorming ideas collected . Share it with the researcher correctly . Also have a SWOT analysis of the person you are trying to meet so that you get to understand in which part is the person strong and can help you . Also carry a recorder with you such meetings because jotting down everything becomes difficult .
Dont believe in what ever is always suggested make sure to come home and do entire research on internet on whatever is shared . That will help you increase your knowledge .
Do some experiments . Some hits and tries randomly and based on results reach to conclusions .
Each of these steps plays a very important role in brainstorming and reaching to a solution . Looking forward to hear from you what were your experiences trying these out .
A similar question has already been asked here https://stackoverflow.com/questions/427532/what-do-you-do-when-youre-stuck.
Sleep is my personal favorite though, although if you're like most college students, you're probably doing a lot of last minute coding and you don't have enough time to sleep and submit your work on time [I was guilty of this too].
What I like to do when I'm stuck on a problem, I usually try to draw out my problems. I just get myself a piece of paper and write down the problems that I encouter. While doing this I like to make Class diagrams/Sequence Diagrams, just to clearify the situation in. Really helps to just get back to old skool pen and paper and not look at your screen for a while.
As a student I also face this problem from time to time. What helps me quite often is to get away from the computer, take a pencil and some paper and start to write down the code by hand. I don't know why but often it is easier for me to solve it on paper than by using an IDE/editor. Probably because your brain works differently then.

debugger's block [closed]

Closed. This question is opinion-based. It is not currently accepting answers.
Want to improve this question? Update the question so it can be answered with facts and citations by editing this post.
Closed 9 years ago.
Improve this question
Do you ever run into a bug where you are just out of ideas and don't know what to try next, and you're getting really annoyed? Are there any general ideas on how to break out of this mode?
When I get blocked like that, the best advice I've found is leave for a while. Whether it's going for a long lunch or leave for the day. Come back fresh and take a new look. Most of the time the answer will be staring you in the face. So far a 10 minute coffee break hasn't been enough for me, but your mileage may vary.
Second, talk to your peers. Walk through everything you've tried. Just ask them to listen, and while you're talking it through, a lot of times, the answer will come to you.
Those are just the two that I use most often when I'm debugging blocked.
Five minute break
Utterly critical, lest you smash your keyboard.
Explain the problem in an email to your sister
Or your two year old son. Someone who wouldn't understand a word* unless you explained it very clearly. You don't need to send the email, you just need to be certain that you understand it inside out. You be surprised at how many times simply restating the problem suddenly makes it obvious to you where you went wrong. This is a good way of discovering what your assumptions were about the problem, and how they might not necessarily be correct.
*That link is to an excellent answer by JaredPar on a different SO question.
Talk to a colleague
By this point you've already 'emailed' the family pet, so you know that you've hopefully covered all the stupid aspects, it's time to talk to a real person. They may have experienced some obscure thing in the past that reminds them of this situation, and they'll definitly have a different perspective. Try to make sure you are clear about what the problem is, not what you think it is. You don't want to bias them. You can and should talk about what they've tried, and explain why you think the problem is in that area (you're probably right) but you don't want to close your mind to their suggestions, even if they don't seem right.
Look at the code again
By this time, you should hopefully be less violent, and you should be armed with new ideas. Start by re-verifying the bug. A simple step, but I've been frustrated for hours on a bug that was in our test script and not in our code. Once you've verified the bug again, start at the top. Verify EVERYTHING. Put a breakpoint at the last point you are 100% confident in, and then work your way forward until you find that the output is broken again. That's a huge success because you now have a hopefully smaller code block to investigate. Then, if necessary, pull in a colleague to look at the actual running code.
I usually take a break... if that doesn't work, I sleep on the problem. (Actually, to be honest, I should say that I spend a sleepless night mulling over the problem).
I almost always have a list of possible solutions ready by morning. :-)
I usually take a few steps:
look at the code that is involved in the functionality that has the bug and place logger messages in a way that they will help me narrow the problem (this allows you to look at the logger later on when you are not that annoyed anymore, and maybe find useful hints :P)
ask my senior collegues for hints
call the client to have a clear understanding of when the problem arises
I usually end up in that mood when I didn't take a structural approach from the beginning.
By iteratively narrowing the area where the problem can live and trying to write the smallest code base that can reproduce the error, I haven't failed yet.
Others have mentioned taking a break or "sleeping on it". This technique is known as (amongst other things) Incubation. Once you embrace the idea you can take it further too.
One important aspect as to really leave the problem behind, confident that you'll have answers later. The dangerous otherwise, especially if sleeping on it, is that you'll be worrying over it up to the last minute, then this becomes an endless cycle that your mind gets caught in overnight. You'll probably end up waking up not too well rested having dreamt many circular dreams. Do this too much and it's a path to depression.
I think if you run into that kind of problem it is time to do some serious refactoring...
Also it could indicate false assumptions. Try to assume programmatically all that you are 'just' assuming. See to it no method-invariants are broken of any methods that are in the stack.
Another good option is to bounce ideas off other developers/team members. Sometimes they will ask you questions you hadn't considered.
If you work alone, it's a good idea to have a few fellow developers who you can chat to to troubleshoot with some different approaches. You'd be amazed how often a fresh perspective can be the breakthrough you need.
Try David Ungars "Shower Methodology":
"If you know what to type, type. If you don't know what to type, take a shower and stay in the shower until you know what to type"
This kind of summons up what the majority likes to do. Take a break ! Doesn't matter what kind of break it is, as long as you are not thinking of the things you were doing before the break. Distraction in any form is good.
Cheers !
I usually take a dry run through the offending method/function, step by step. And don't assume the bug is coming from there, it could be coming from anywhere before it.
Use a proper debugger, don't use a series of printfs.

Standard methods of debugging

What's your standard way of debugging a problem? This might seem like a pretty broad question with some of you replying 'It depends on the problem' but I think a lot of us debug by instinct and haven't actually tried wording our process. That's why we say 'it depends'.
I was sort of forced to word my process recently because a few developers and I were working an the same problem and we were debugging it in totally different ways. I wanted them to understand what I was trying to do and vice versa.
After some reflection I realized that my way of debugging is actually quite monotonous. I'll first try to be able to reliably replicate the problem (especially on my local machine). Then through a series of elimination (and this is where I think it's problem dependent) try to identify the problem.
The other guys were trying to do it in a totally different way.
So, just wondering what has been working for you guys out there? And what would you say your process is for debugging if you had to formalize it in words?
BTW, we still haven't found out our problem =)
My approach varies based on my familiarity with the system at hand. Typically I do something like:
Replicate the failure, if at all possible.
Examine the fail state to determine the immediate cause of the failure.
If I'm familiar with the system, I may have a good guess about to root cause. If not, I start to mechanically trace the data back through the software while challenging basic assumptions made by the software.
If the problem seems to have a consistent trigger, I may manually walk forward through the code with a debugger while challenging implicit assumptions that the code makes.
Tracing the root cause is, of course, where things can get hairy. This is where having a dump (or better, a live, broken process) can be truly invaluable.
I think that the key point in my debugging process is challenging pre-conceptions and assumptions. The number of times I've found a bug in that component that I or a colleague would swear is working fine is massive.
I've been told by my more intuitive friends and colleagues that I'm quite pedantic when they watch me debug or ask me to help them figure something out. :)
Consider getting hold of the book "Debugging" by David J Agans. The subtitle is "The 9 Indispensable Rules for Finding Even the Most Elusive Software and Hardware Problems". His list of debugging rules — available in a poster form at the web site (and there's a link for the book, too) is:
Understand the system
Make it fail
Quit thinking and look
Divide and conquer
Change one thing at a time
Keep an audit trail
Check the plug
Get a fresh view
If you didn't fix it, it ain't fixed
The last point is particularly relevant in the software industry.
I picked those on the web or some book which I can't recall (it may have been CodingHorror ...)
Debugging 101:
Reproduce
Progressively Narrow Scope
Avoid Debuggers
Change Only One Thing At a Time
Psychological Methods:
Rubber-duck debugging
Don't Speculate
Don't be too Quick to Blame the Tools
Understand Both Problem and Solution
Take a Break
Consider Multiple Causes
Bug Prevention Methods:
Monitor Your Own Fault Injection Habits
Introduce Debugging Aids Early
Loose Coupling and Information Hiding
Write a Regression Test to Prevent Re occurrence
Technical Methods:
Inert Trace Statements
Consult the Log Files of Third Party Products
Search the web for the Stack Trace
Introduce Design By Contract
Wipe the Slate Clean
Intermittent Bugs
Explot Localility
Introduce Dummy Implementations and Subclasses
Recompile / Relink
Probe Boundary Conditions and Special Cases
Check Version Dependencies (third party)
Check Code that Has Changed Recently
Don't Trust the Error Message
Graphics Bugs
When I'm up against a bug that I can't get seem to figure out, I like to make a model of the problem. Make a copy of the section of problem code, and start removing features from it, one at a time. Run a unit test against the code after every removal. Through this process your will either remove the feature with the bug (and hence, locate the bug), or you will have isolated the bug down to a core piece of code that contains the essence of the problem. And once you figure out the essence of the problem, its a lot easier to fix.
I normally start off by forming an hypothesis based on the information I have at hand. Once this is done, I work to prove it to be correct. If it proves to be wrong, I start off with a different hypothesis.
Most of the Multithreaded synchronization issues get solved very easily with this approach.
Also you need to have a good understanding of the debugger you are using and its features. I work on Windows applications and have found windbg to be extremely helpful in finding bugs.
Reducing the bug to its simplest form often leads to greater understanding of the issue as well adding the benefit of being able to involve others if necessary.
Setting up a quick reproduction scenario to allow for efficient use of your time to test any hypothosis you chose.
Creating tools to dump the environment quickly for comparisons.
Creating and reproducing the bug with logging turned onto the maximum level.
Examining the system logs for anything alarming.
Looking at file dates and timestamps to get a feeling if the problem could be a recent introduction.
Looking through the source repository for recent activity in the relevant modules.
Apply deductive reasoning and apply the Ockham's Razor principles.
Be willing to step back and take a break from the problem.
I'm also a big fan of using process of elimination. Ruling out variables tremendously simplifies the debugging task. It's often the very first thing that should to be done.
Another really effective technique is to roll back to your last working version if possible and try again. This can be extremely powerful because it gives you solid footing to proceed more carefully. A variation on this is to get the code to a point where it is working, with less functionality, than not working with more functionality.
Of course, it's very important to not just try things. This increases your despair because it never works. I'd rather make 50 runs to gather information about the bug rather take a wild swing and hope it works.
I find the best time to "debug" is while you're writing the code. In other words, be defensive. Check return values, liberally use assert, use some kind of reliable logging mechanism and log everything.
To more directly answer the question, the most efficient way for me to debug problems is to read code. Having a log helps you find the relevant code to read quickly. No logging? Spend the time putting it in. It may not seem like you're finding the bug, and you may not be. The logging might help you find another bug though, and eventually once you've gone through enough code, you'll find it....faster than setting up debuggers and trying to reproduce the problem, single stepping, etc.
While debugging I try to think of what the possible problems could be. I've come up with a fairly arbitrary classification system, but it works for me: all bugs fall into one of four categories. Keep in mind here that I'm talking about runtime problems, not compiler or linker errors. The four categories are:
dynamic memory allocation
stack overflow
uninitialized variable
logic bug
These categories have been most useful to me with C and C++, but I expect they apply pretty well elsewhere. The logic bug category is a big one (e.g. putting a < b when the correct thing was a <= b), and can include things like failing to synchronize access among threads.
Knowing what I'm looking for (one of these four things) helps a lot in finding it. Finding bugs always seems to be much harder than fixing them.
The actual mechanics for debugging are most often:
do I have an automated test that demonstrates the problem?
if not, add a test that fails
change the code so the test passes
make sure all the other tests still pass
check in the change
No automated testing in your environment? No time like the present to set it up. Too hard to organize things so you can test individual pieces of your program? Take the time to make it so. May make it take "too long" to fix this particular bug, but the sooner you start, the faster everything else'll go. Again, you might not fix the particular bug you're looking for but I bet you find and fix others along the way.
My method of debugging is different, probably because I am still beginner.
When I encounter logical bug I seem to end up adding more variables to see which values go where and then I go and debug line by line in the piece of code that causing a problem.
Replicating the problem and generating a repeatable test data set is definitely the first and most important step to debugging.
If I can identify a repeatable bug, I'll typically try and isolate the components involved until I locate the problem. Frequently I'll spend a little time ruling out cases so I can state definitively: The problem is not in component X (or process Y, etc.).
First I try to replicate the error, without being able to replicate the error it is basically impossible in a non-trivial program to guess the problem.
Then if possible, break out the code in a separate standalone project. There are several reasons for this: If the original project is big it quite difficult to debug second it eliminates or highlights any assumptions about the code.
I normally always have another copy of VS open which I use for the debugging parts in mini projects and to test routines which I later add to the main project.
Once having reproduced the error in the separate module the battle is almost won.
Sometimes it is not easy to break out a piece of code so in those cases I use different methods depending on how complex the issue is. In most cases assumptions about data seem to come and bite me so I try to add lots of asserts in the code in order make sure my assumptions are correct. I also disabling code by using #ifdef until the error disappears. Eliminating dependencies to other modules etc... sort of slowly circling in the bug like a vulture ..
I think I don't have really a conscious way of doing it, it varies quite a lot but the general principle is to eliminate the noise around the issue until it is quite obvious what it is. Hope I didn't sound too confusing :)

How not to rush yourself? [closed]

Closed. This question is opinion-based. It is not currently accepting answers.
Want to improve this question? Update the question so it can be answered with facts and citations by editing this post.
Closed 4 years ago.
Improve this question
I often find that I do a less than complete work on a feature, especially in the Design phase. I detect several reasons:
I'm over-optimistic
I feel the need to provide quick solutions, so sometimes I fool myself into thinking the design is fool-proof when in fact it's still full of holes, just to get the job done faster. Of course I end up paying dearly later.
I'm aware of this behavior of mine for some time, yet I still find I don't manage to compensate. Have you encountered similar problems? How do you approach solving them?
I use a couple of techniques. The first is a simple paper to-do list. In the morning I write down my tasks for the day. I try to work on a task until I can cross it off. I cross it off only when I'm done to my own satisfaction. My to-do list helps me stay focused. When an interruption comes in, I can consciously choose whether it is important enough to interrupt what I'm doing now.
The second technique I use is to give up on the idea of "done" for a design. Instead, I focus on what I've started calling "successions", where a design goes through predictable stages. Each stage supports the current functionality well and will be succeeded at some point by the next stage. This lets me do a good job, a job I can be proud of, without over-designing.
I have the intuition that there is a small catalog of such successions (like http://www.threeriversinstitute.org/FirstOneThenMany.html) that would cover most of design. In the meantime, I try to remember that "sufficient to the day are the troubles thereof".
I run into this problem a lot.
My solution is a notebook. (The old fashioned paper kind).
I write out how I'm planning on implementing the solution as an bulleted overview list, and then I try and flesh out each point on the list.
Often, during that process, I come across issues I hadn't thought of.
Of course, the 80/20 rule still applies... I still come across things when I'm actually doing the implementation that hadn't occurred to me, but with experience these tend to diminish.
EDIT: If I'm still not sure at the end of this process, I put together a throwaway prototype testbed... It's important to make sure it's throwaway, because otherwise you run the risk of including some nasty hacks in your real codebase.
It's very common to miss edge-cases and detail when you're in the planning phase of a project, especially in the software development field. Please don't feel that this is a personal failing; it's something endemic.
To counter this, many software development methodologies have emerged. Most recently there has been a shift by many development teams to 'agile' methods, where there is a focus on rapid development with little up-front technical design (after all, many complexities are only discovered when you actually begin developing). I'm currently using the Scrum system, which has been excellent in my small team:
http://en.wikipedia.org/wiki/Agile_methods
http://en.wikipedia.org/wiki/Scrum_%28development%29
If you find that your organisation will not accept what they may regard as a radical shift in approach, it may be worth investigating whether they will agree to the development of a prototype system. This means that you could code up a feature to investigate the technologies involved and judge whether it's feasible, without having to commit to full development, a quality bar, testing schedules etc. The prototype should be thrown away once the feasibility has been proved or disproved, then proper development may begin, including all that you've learned in the process.
If your problem is more related to time management, then I'd recommend the Getting Things Done approach (http://en.wikipedia.org/wiki/Getting_things_done). This is pragmatic and simple, concentrating on making you productive without overloading you with information that isn't immediately relevant to your current work. I've found that I get overwhelmed with project/feature ideas at times and it really helps to write everything down and file it for a later time when I have the resources available to work effectively.
I hope this helps and best of luck!
Communication.
The best way to not rush yourself into programming mistakes is communication. Yes, good ol' fashioned accountability. If another person in the office is involved in the process, the better the outcome. If a programmer just takes on the task without any concern for anybody else, then there is a higher possiblity for mistakes.
Accountability Checklist:
How do we support this?
Who needs to know what has changed?
Why are we doing this in the first place?
Will there be anybody who doesn't want this changed?
Will someone else understand how I did this?
How will the user perceive and use this change?
A skepticle comrad is usually good enough to help. Functional Specifications are good, they usually answer all of these thoughts. But, sometimes a conversation with another person can help you with it and you can get changes out the door faster.
I have learned, through years of mistakes (though still making them), that almost anything I want to use repeatedly, or distribute, needs to be designed properly. So getting burned enough times will end your optimism.
When getting pressure from management, I tell them I will have to put in the thought anyway, so I should do it when it's cheap. I think on paper as well, so I can actually prove that I'm doing something and it keeps my fingers on the keyboard, both of which provides a soothing effect to management. ;-)
At the risk of sounding obvious - be pessimistic. I had a few experiences where I thought "that should take a few hours" and it ended up taking a couple days because of all the little things that pop up unexpectedly.
By far the best way I've found to manage things is to (much like Andrew's answer) write out the design and requirements as a starting point. Then I go through and look for weak points in the design, gotchas and additional use cases etc. I try to look at this as a critical exercise - there's no code written yet, so this is the time to be totally ruthless and look for every weak point. Look for error conditions you'll have to handle, and whatever amount of time you think it will take to complete each feature/function, pad that amount by a lot. I've had times where I've doubled my initial estimate and still not been that far off the mark.
It's very hard as a programmer to realistically project debugging time - writing the code is easy to estimate, but debugging that into functioning, valid code is something else entirely. Therefore I find there's no exact science to it but I just pad tasks by a whole bunch, so that I have plenty of breathing room for debugging.
See also Evidence Based Scheduling which is a fascinating concept in scheduling developed by FogCreek for their FogBugz product.
You and the rest of the world.
You need more a more detailed design, more accurate estimate, and the willingness to accept that sometimes the optimal solution is not necessarily the best solution (e.g., you could code some loop in assembler to get optimal performance, but that's going to take a lot longer than just doing
for (i=1; i<=10; i++) {}
). Is the time spent doing it really worth it for an accounting package over a missile system.
I like to designing, but over time I've found that much design up front is a lot like building castles into the sky - it's too much speculation, however well-educated, missing critical feedback from actually implementing and using the design.
So today I'm much more into accepting that while implementing a design I will learn a lot of new stuff about it, and need to feed that learning back into the design. Doing that is a skill that is fun to learn, including the skills to keep a design flexible by keeping it simple, free of duplication and cohesive and decoupled, of changing the design in small, controlled steps (=refactoring), and writing the necessary extensive suite of automated tests that make this kind of changes safe.
This seems to be a much more effective approach to me than getting better at "up front design speculation" - and addtionally it makes me equally well prepared for the inevitable moment when the design needs to be changed due to a simply unforseeable change in the requirements.
Divide, divide, divide. List all the steps that will be required to finish the project, then list all the steps those steps will require to be concluded, and so on until you reach atomic items you are absolutely sure you can finish in a day or less. Add the duration of all these values to arrive at a length of time.
Then double it. Now you have a number that, if depressing, is at least somewhat realistic.
If possible "Sleep on your design" before publishing it. I find after I leave work, I usually think of things I have missed. This usually happens while I am lying in bed before falling asleep or even while showering the next day.
I also find it valuable to have a peer/friend that I trust review what I have before distributing it. Somebody else almost always sees something I didn't think of or miscommunicated.
I like to do as others stated here. Write down in pseudo code what the flow of your app will be. This immediately highlights some detailed areas that may require further attention that where not apparent up front.
Pseudo code is also readable to business users who can verify your approach meets their needs.
Using pseudo code also creates a nice set of methods that could be put to use as an interface in the final solution. Once the pseudo code is fairly tight, look for patterns and review some common GOF patterns. They do not have to be perfect but using them will sheild you from having to rewrite the code later during the revisions that are bound to come along.
Just taking an hour or two write psuedo code, yields some invaluable time saving pieces later on:
1. An object model emerges
2. The program's flow is clearly defined for others
3. It can be used as documentation of your design with some refinement
4. Comments are easier to add and will be clearer for someone else reviewing your code.
Best of luck to you!
I've found that the best way to make sure you've chosen a good design is to make sure that you understand the problem, know the limitations you have, and know what things are must-haves vs. nice-to-haves.
Understanding the problem will involve talking to the people who have the need and keeping them anchored to what needs to get done first instead of how they think it ought to get done. Once you know what actually has to happen, you can go back and talk over requirements about how.
Knowing your limitations may be quite easy: needs to run on the iPhone; has to be a web application; needs to integrate with the already-existing Java code and deployment setup; and so on. It may be quite difficult: you don't know what the potential size of your user base is (hundreds? thousands? millions?); you don't know whether you'll need to localize it (though if you're not sure, assume you will have to).
Must-haves vs, nice-to-haves: this is possibly the most difficult part. Users very often have emotional attachments to "requirements" ("It should look just like Excel") that are not actually part of the "has to happen" stuff. You often have to juggle functionality vs. desires to get an acceptable implementation. You can't always give everyone a pony.
Make sure you write all this down! Even if it evolves along the way, or the design is small, having a "this is what we're planning to do now" guide to refer to when you need ot make a decision about committing resources makes it easier to restrain yourself from implementing a really cool whiz-bang feature instead of a boring must-do.
Since you recognize that you feel the need to provide a quick solution, perhaps it will slow you down to realize that you can probably solve the problem faster and deliver it sooner if you spend more upfront time in design. For instance if you spend 3 hours designing and 30 hours writting code, it probably means that if you spend 6 hours designing you might need to only spend 10 hours writing code. (These are not actual figures just examples). You might try to quantify this for yourself on the next few projects you do. Do a couple where you behave as you normally would and see what ratio of design/codewriting/testing&debugging you actually do. Then on the next project deliberately increase the percentage of time you spend on design phase and see if it does shorten the time needed for the other phases. You will have to try for several projects on this as well to get a true baseline since the projects may be quite different. Do it as a test to see if you can improve your performance on the the other phases and thus deliver a faster product if you spend 20% more time or 50% more time or 100% more time on design.
Remember the later in the process you find the problem with a design the harder (and more time-consuming) it is to fix.

Techniques to follow when you are stuck programming [closed]

Closed. This question is opinion-based. It is not currently accepting answers.
Want to improve this question? Update the question so it can be answered with facts and citations by editing this post.
Closed 7 years ago.
Improve this question
When I am stuck with a problem:
I search Google for code snippets.
I look at isolating the problem, so that I can better explain it to others in order to get answers.
What search techniques do you use to find the solution to your problem?
I started asking questions in Stack Overflow.
What other techniques or methods do you follow, to fix the problem more quickly?
Go and do something else. No, really. I've found that putting the problem away in the back of my mind helps. I can't count the number of times I thought of a great solution to something I've been working on when I was working on something else, or watching TV, or eating. It seems your brain is still working on the problem in the background.
If that fails to solve your problem, try talking to someone. You'd be surprised how often others can give solutions to your problem that are so simple you'd facepalm.
Well there's:
Google
Google
Google
Stack Overflow
Google
Google
Maybe a book if I have one.
Seriously, I started (hobby) programming in the 1980s and even into the mid 90s you had to know things and have a technical library. Then Google came along and it's easier to Google something than it is to look up (bookmarked!) API documentation (Google "java stringbuilder" will get me there faster than navigating will) let alone an actual book (electronic or paper).
Most problems you're trying to solve have been solved before. Many times.
The rest of debugging comes down to decomposition, possibly unit testing (which is related to decomposition) and verifying your assumptions.
By "decomposition", I mean that your solution is structured in such a way that small pieces can be individually tested and readily understood. If you have a 7000 line method you're (probably) doing something wrong.
Understanding what assumptions you've made is key too so you can verify them. For example, when I started with PHP I wrote a piece of code like this:
$fields = $_SESSION["fields"]; // $fields is an associative array
$fields["blah"] = "foo";
and I was scratching my head trying to figure out why it didn't work (the array wasn't being updated next time I queried $_SESSION). I came from a Java background where you might do this:
Map fields = (Map)httpSession.get("fields");
fields.put("blah", "foo");
and that would most definitely work. PHP however copies the array. A working solution is to use references:
$fields =& $_SESSION["fields"]; // $fields is an associative array
$fields["blah"] = "foo";
or simply:
$_SESSION["fields"]["blah"] = "foo";
The last thing I'll say about debugging and writing robust code in general is to understand the boundaries of your solution. By this I mean if you're implementing a linked list then the boundary conditions will revolve around when the list is empty.
Explain the problem to a colleague, or write it down to describe it. That will makes you think a different way, from a different perspective. In order to be more accurate, and to describe the context of the problem, you'll step back, get a higher level view of the problem, you may find out think you overlooked something that is actually important.
Sometimes, you even find the explanation before ending your description.
My best friend for many years has been to jump on my bike and go home. Just getting away from the keyboard has solved many problems over the years for me.
If the problem lasts to the end of the day, I try and consciously lock the problem away for solving before I go to sleep.
I realise this sounds a bit out there, but it has been very common in my experience that I'll wake up with at least an alternate approach to the problem, if not the full-on solution. The idea is not to stress about it - but actively decide to solve it over night. That way you can go to sleep without worry.
I think eating well, regular exercise and good sleep are huge contributors to the problem-solving process.
Usually I'll try nut out the problem for a few hours or so, trying different things writing it on paper, making diagrams. If none of that works I'll usually work through the following options.
Put a sticky note on my monitor and keep going with something else
Glance at the note through out the next few hours to keep the problem in the back of my mind
Google for similar problems and the methods used
Consult a co-worker or a friend
Ask on a forum such as stackoverflow
Give up and design the problem away or design a way around the problem so it can be dealt with some other time and stick a TODO note at the site of said workaround
Don't forget Google Code Search
It's often best to clear your head by doing something other than programming for a little while. See this answer for an example - I did it while struggling with a particularly thorny bug, and when I came back to the problem I solved it in about a minute.
Usually I try to solve it until I go to sleep.. Sometimes I write on paper what the code is doing and then I divide it in pieces; I try to know how the variables of the program change when it's running.
Try solving a much smaller version of the problem first and see how you get on with that.
Once you've done that the bigger problem won't look so scary.
Ask yourself: is solving this particular tricky problem really important to what you doing?
For the purposes of your application (or whatever the big picture is) is there a similar but easier problem that you could address to accomplish broadly the same thing.
Normally, I would get pen and paper and try to work out the details of the problem there. If that doesn't help, Google. Failing that, I'd do something else for a while, or ask online. Worked for me so far.
The fact you are stuck might be a 'code-smell'. Suggesting that their is something wrong with the design or approach somewhere else. Try to put your finger on what's causing this and fix this instead.
When you come back to your problem it might no longer exist.
One more time, browse thru what I think might be relevant, then take nap.
There are two other answers which mention sleeping or napping, but this deserves more emphasis. It is now known that there's SERIOUS machinery in there which goes to work when you sleep. Google (( CBS SCIENCE SLEEP )) will get you to a great free video.
If I can't figure out how to solve the real problem, I try to consider a simplified version of the problem. To take a simple example: I recently had the problem of finding a set of shipping routes to get an item from point A to point B, when there is not necessarily a direct route from A to B, but there might be an A to C and then C to B, or A to C, C to D, and then D to B. (I'm sure the airlines and railroads do this all the time.) That was fairly complex, so I tried looking first at the simple case: a direct A to B. That was easy. Then consider how I'd handle it with one stop along the way. Then consider two stops. At that point I was able to see the pattern to a solution.
Solutions to a simplified version of the problem may end up being a part of the bigger solution, with some additional complexity wrapped around them. But even if not, the exercise of solving the easier problem often gives you ideas on how to solve the real problem.
The main techniques I use (should be followed in order so that you can reuse what you have done in previous steps to be more efficient):
Define your issue: Try to clearly define what's the problem, and what's expected. See 2 to help you.
Collect data about the bug: Log everything: your attempts, the expected result, the observed result. This will avoid the need to redo several times the same tests (because your mind cannot memorize it all), and probably help you see the bigger picture.
Reduce your problem. This is true in general for any abstract modelling of natural phenomenons, but it's even more true of programming, because programs are very complex entities. You should try to reduce your code to a minimal program that reproduces your issue. Automated tools exist.
Talk to someone: several anecdotes affirm than about 2/3 of the bugs are resolved just by talking about it. See the Helpful Teddy Bear anecdote. If you have previously reduced your program to a minimal program, and have a clear definition of your issue, both will be useful to your explanation.
Reach for collaborative help: search on Google and on StackOverflow, and post if you can't find anything that answers your problem (but first see 1, you must have a clear definition of your problem).
As you can see, I put the collaborative help as the last step, because you should only ask for help after you have clearly defined your issue and tried to reduce the problem and fix it by yourself. If you reach for collaborative help before having tried the previous steps, you will either end up with a poor help or figure it out by yourself as soon as you have posted.
Also you can be interested in the Coursera Software Debugging course, which also describes several automated debugging methods.
Go to the toilet.
You move, so your brain gets oxygen.
You relax, so you focus on other things.
Peeing for innovation! :)

Resources