premature optimization java

Most users are (to say the least) not frantically using every CPU cycle available anyhow, they are probably waiting for the network to do something. code that performs its intended function, quickly and completely with simplest logic reasonable.) The use case in question was a statically initialized collection thats sole purpose was to serve as a look-up table. IMHO, most optimization should occur at design stage. A single request was made for the entire data, like Google Maps fetching the entire world. And typically, you the architect/designer/programmer/maintainer need clear and concise code in order to understand what is going on. It is also easy to latch onto a class that provides a given piece of functionality without checking whether the functionality is provided at an acceptable level of performance for the scale of intended usage. believe the same viewpoint should prevail in software engineering. technique is different but not What are the general programming practices that are important with respect to performance in Java? Use a profiler to find the real bottleneck. Not taking the time to learn what is good performing database design is developer laziness, not best practice. “Premature optimization is the root of all evil” ~ Donald Knuth. Optimisation is simply refinement to reach an optimal solution, it is often most efficiently done at design stage. As Johnson states in the previously cited book, "Few things in programming are harder than optimizing existing code. This has been an interesting exercise in premature optimization. It can be difficult to figure out exactly when things are moved from heap to stack, but using the Caliper microbenchmark framework you can get a good idea. Donald Knuth is often quoted as saying “premature optimization is the root of all evil.” Often in the JavaRanch forums, we see questions like: which is faster stringBuilder.append(‘a’) or “a” + “b” (The answer is these two expressions are supposed to generate to the same byte code if … How to filter paragraphs by the field name on parent using entityQuery? The answer may depend on the JVM you use to run the code, but in most cases the above will NOT be faster. Yet it was a quote in favor of appropriately applied micro-optimizations when used by an experienced hand holding a profiler. Because it can't work well ever, so don't use quickness as a substitute for good code. Second, verify that the code is correct. Premature Optimization is a Real Problem. Beyond such idioms, take shortcuts at your peril. Developing bad code, expecting for profiling later made the project fail. Donald Knuth is often quoted as saying “premature optimization is the root of all evil.” Often in the JavaRanch forums, we see questions like: which is faster stringBuilder.append(‘a’) or “a” + “b” (The answer is these two expressions are supposed to generate to … How were drawbridges and portcullises used tactically? Stack Overflow for Teams is a private, secure spot for you and And in those cases where it actually is necessary, it's rarely sufficient. Discusses code optimization and how optimizing premature is considered the root of all evil. Applying Appropriate Language Practices is Not Premature Optimization Most programming languages I'm familiar with often offer multiple ways to accomplish the same thing. (Knuth, Donald. It's more about burning time on the what ifs that are potential performance problems depending on the usage scenarios. [...]. Categories . Basically profiling is needed when an assumption does not hold, and the profiler is needed to tell you WHAT assumption broke. is performed about a million or so times in the program. IMHO, 90% of your optimization should occur at design stage, based on percieved current, and more importantly, future requirements. Okay, that’s non entirely wrong. Efficiency. Thanks for contributing an answer to Stack Overflow! I'm also curious how readable other people think my other suggestions are. Also note how he isn't just criticizing these "pennywise-and-pound-foolish" programmers, but also the people who react by suggesting you should always ignore small inefficiencies. Note that 'efficient' code is not necessarily the same as 'optimised' code. In reaction to a lot of the other comments posted on this question: algorithm selection != optimization. (Although if you write your own sort routine instead of using the library sort routine, one hopes you have a very good reason.). Premature Optimization in Java 2014-09-25 A few months ago I implemented the Möller-Trumbore ray-triangle intersection algorithm (trivia: the inventor, Tomas Möller, … ... "Premature optimization is the root of all evil." Databases do not refactor easily. javascript required to view this site. Choose the right data structures and algorithms for the problem. First and Foremost - NO premature optimizations. (Move immutable expressions outside of the loop body. We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. In my experience, most optimization problems can be solved at either the architecture/design or data-structure/algorithm level. Programmers waste enormous amounts of time thinking about, or worrying This site uses Akismet to reduce spam. It was supposed to show a chronological chart with all patients' history. Are multiple indexes on MYSQL table reason for slow UPDATES and INSERTS? should be supplied automatically unless it has been specifically Java Performance Tuning. By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Service. Such data might come from user feedback for example. Keep in mind how he used "optimized" in quotes (the software probably isn't actually efficient). There is a reason why quick and dirty is called that. By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy. How can I show that a character does something without thinking? Any code change that is done before stage #3 is definitely premature. Have Texas voters ever selected a Democrat for President? It can even be slower than the non-inlined version. It's worth noting that Knuth's original quote came from a paper he wrote promoting the use of goto in carefully selected and measured areas as a way to eliminate hotspots. Well, this is not completely wrong. His quote was a caveat he added to justify his rationale for using goto in order to speed up those critical loops. programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other all forums. I did not suspect that code until the profiler pinpointed it as the culprit! The engineers of the project should be aware of where performance bottlenecks are. The concept of premature optimization was first made prominent in the field of software engineering. (and so on). These types of optimizations typically relate to algorithm selection and storage strategy, and are extremely difficult to reverse into existing code. That would make it an optimization- "I'd rather program in C#, but I have to use C++ because it's faster. Redesign is more costly than optimising a design in obvious ways from the start. I agree with the idea behind it, but also: unless the implementation is bound completely by CPU cycles, getting a measurement that's both reproducable and can be generalized is hard - and the more stable it is, the less realistic it is, too. The Java 6 HotSpot/JIT implementation optimizes for biased locking by default. It is attributed to Sir Tony Hoare, though it was popularized by Donald E. Knuth, who said that: “There is no doubt that the holy grail of efficiency leads to abuse. "We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil." Why do Hopping Hamiltonians have physical significance? Try looking up same examples for large sparse matrices. I think "premature optimisation" is incredibly subjective. The memory subsystem is 10 to 100 times slower than the CPU, and if your data gets paged to disk, it's 1000 to 10,000 times slower. A common quote linked with Donald E. Knuth of TeX fame is “premature optimization is the root of all evil”. Learn how your comment data is processed. According to the pioneering computer scientist Donald Knuth, "Premature optimization is the root of all evil." His quote was effectively a part of a big disclaimer, just like someone doing a motorcycle jump over a flaming fire pit might add a disclaimer that amateurs shouldn't try this at home while simultaneously criticizing those who try without proper knowledge and equipment and get hurt. Premature optimization takes up a lot of time, and more often than not, developers need to do it again. Is there still a way to avoid a hard Brexit on January first that does not require agreement of all individual EU members? Third, make it fast. Required fields are marked *. It's best to do obvious things right from the start, but for everything else there's profiling. It involves the selection of proper data structures and algorithms, which often have a big performance impact and can't necessarily be exchanged later. efficiencies, say 97% of the time; premature optimization is the root Premature Optimization in Java 2014-09-25 A few months ago I implemented the Möller-Trumbore ray-triangle intersection algorithm (trivia: the inventor, Tomas Möller, works … I've become convinced that all compilers written from now on should be @haslersn : "Knuth was talking about small efficiencies" Donald Knuth: "The conventional wisdom shared by many of today's software engineers calls for ignoring efficiency in the small; but I believe this is simply an overreaction to the abuses (...) In established engineering disciplines a 12 % improvement, easily obtained, is never considered marginal (...)". Nonetheless, my solution failed spectacularly by being far too flexible. 23 votes, 16 comments. It is something they should always try to avoid in their daily work. Asking for help, clarification, or responding to other answers. C++ hasn't been a hassle to program in since shared_ptr and std::vector were invented. If you don't fit in the "pennywise-and-pound-foolish" category, then you aren't prematurely optimizing by Knuth's standards, even if you're using a goto in order to speed up a critical loop (something which is unlikely to help much against today's optimizers, but if it did, and in a genuinely critical area, then you wouldn't be prematurely optimizing). Interrupting your code-writing to look for alternatives to common programming constructs / library routines on the off-chance that there's a more efficient version hanging around somewhere even though for all you know the relative speed of what you're writing will never actually matter... That's premature. designed to provide all programmers with feedback indicating what The other day the reddit community discarded my advice for switching from text-based to binary serialization formats. However, the Java runtime can still just-in-time optimize your code to avoid unnecessary heap allocations. yes, Tony Hoare first said the "premature optimization is the root of all evil part", but Knuth quoted/paraphrased him adding the rest, i believe. A) You can reach the goal performance threshold by performing high-level optimizations, so it's not necessary to fiddle with the expressions. Most developers think that performance optimization is a complex topic that requires a lot of work experience and related knowledge theory. Finally, to the frequently-quoted part: There is no doubt that the grail of efficiency leads to abuse. Java Performance. i,e, very early on. rev 2020.12.10.38156, Stack Overflow works best with JavaScript enabled, Where developers & technologists share private knowledge with coworkers, Programming & related technical career opportunities, Recruit tech talent & build your employer brand, Reach developers & technologists worldwide, It's kind of ironic that many people who yell "Premature optimization is the root of all evil" themselves have prematurely optimized the quote: (cont), "We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Other optimizations such as using sargeable code, selecting what look to be the best possible indexes, etc. But then, I have a strong background in low level code & cost, and would have instinctively shunned anythign that relies on (significantly repeated) removal of the first string character. So, was that premature optimization or not? ", @user258365: Brute force would be to use a string representation that does not need to make a copy for sub strings. optimizations [using gotos] are not difficult to learn and, as I have Are you a java premature optimization professional? Is there a difference between a tie-breaker and a regular vote? Premature optimization to me means trying to improve the efficiency of your code before you have a working system, and before you have actually profiled it and know where the bottleneck is. You have a measurement (profile or similar) showing that the optimization could improve things. Thing is that bottlenecks often come up in sections of code you never thought would be a problem. only make sense to do at design time. (5,900 words) ... "Premature optimization is the root of all evil." >make code faster >"premature optimization is the root of all evil" - "/g/ - Technology" is 4chan's imageboard for discussing computer hardware and software, programming, and general technology. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Avoid regular expressions. attempts at efficiency actually have a strong negative impact when I try to only optimise when a performance issue is confirmed. Donald E. Knuth wrote in his 1974 paper titled Structured Programming With Go To Statements that “we should forget about small efficiencies, say about 97 percent of the time: premature optimization is the root of all evil. I think premature optimization is often executed because the developer underestimates the speed of modern computers. My question is, if a particular Ensure Sufficient Java VM Memory Allocation. As Johnson states in the previously cited book, "Few things in programming are harder than optimizing existing code. Most developers expect that performance optimization is the complicated topic that requires a lot of experience in addition to knowledge. But if you’re in … Save my name, email, and website in this browser for the next time I comment. And in the teaching material where these abstract design concepts are taught, such as notification-driven architecture, and information-hiding where simply setting a boolean property of an object can have an unbounded ripple effect of activities, what is the reason given? My advice: Try to only pay the cost of optimisation when you can quantify the benefit. Next, I removed the temporary Vec objects. The way I see it is, if you optimize something without knowing how much performance you can gain in different scenario IS a premature optimization. In the past I've worked on some time critical code (an RSA implementation) where looking at the assembler that the compiler produced and removing a single unnecessary instruction in an inner loop gave a 30% speedup. If a particular optimization is clear and concise, feel free to experiment with it (but do go back and check whether that optimization is effective). From a database perspective, not to consider optimal design at the design stage is foolhardy at best. Evan Miller, Premature Optimization and the Birth of Nginx Module Development (2011) — ironically, despite the title, this doesn’t really sound like an instance of premature optimization; instead he describes an initial difficult but successful optimization, that was later obsoleted by a more clever and simpler optimization. Linus is wearing a blue shirt! So my advice, optimize early, based on your requirements, not your code, and look to the possible extended life of your app. ), EDIT: In response to comments, using quicksort instead of a simpler algorithm like insertion sort is another example of an idiom that everyone understands and expects. This has been an interesting exercise in premature optimization. But doing this has no use until you are certain which parts of code need this kind of optimization and optimizing will (could?) "Premature optimization" is a phrase used to describe a situation where a programmer lets performance considerations affect the design of a piece of code. if, say, the average value of n is about 20, and if the search routine The standard answer to these optimisation-tips questions is to profile your code and see if it's a problem first, and if it's not, then therefore your new technique is unneeded. of all evil. To learn more, see our tips on writing great answers. Any time you're trying to promote carefully-applied micro-optimizations as Knuth promoted above, it's good to throw in a disclaimer to discourage novices from getting too excited and blindly taking stabs at optimization, like rewriting their entire software to use goto. The root of premature optimization is engineers hating the thought of rewriting. In established engineering disciplines a If I am writing some code and I know that I should be using a Hashtable then I will do that. When trying to fry onions, the edges burn instead of the onions frying up. You are missing the single most important QA parameter in you list above; Meeting requirements. Is there any role today that would justify building a large single dish radio telescope to replace Arecibo? Profiling dispenses with pretense and shows the actual cost centers of the program. All CS research is a waste of the taxpayers' money and should be halted immediately. One of the groups of people he was criticizing who echo this "conventional wisdom" as he put of always ignoring efficiencies in the small are often misusing his quote which was originally directed, in part, against such types who discourage all forms of micro-optimization. For instance I found that "delete the character at position 0" for StringBuffers in Java worked fine for the junit tests, but VERY slow for large strings. What are the general programming practices that are important with respect to performance in Java? Among these are: Optimisation (going for performance) often comes at the expense of other parameters, and must be balanced against the "loss" in these areas. calls for ignoring efficiency in the small; but I believe this is Unfortunately, this is why optimization is uniquely satisfying to any programmer's ego. As Knuth said, We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Put the most common value first in a switch/case, etc. java - the - why is premature optimization bad . That's "almost trivial" for immutable reference counted strings. Then attack the parts which take the most time. The Java JIT compiler tries to detect objects that don’t escape a method and allocate those on the stack instead. instead of String + String (in a loop); It seems in most JavaScript implementations, it is faster to do too. Optimizing an application for performance optimization may not be an easy task, but that does not mean you can not do anything without knowledge. site design / logo © 2020 Stack Exchange Inc; user contributions licensed under cc by-sa. +1 for "optimize during design". In almost every case, the reason for the suboptimal performance is what I call galloping generality, which is the use of abstract multi-layer classes and thorough object-oriented design, where simple concepts would be less elegant but entirely sufficient. Keep on top of the latest news about java premature optimization with these blogs. I benchmarked two versions of my intersection code against each other. The point is to keep the code clear and concise throughout the development process, until the benefits of performance outweigh the induced costs of writing and maintaining the optimizations. Here's an example. Besides, 'performance' in the sense of 'as fast as possible' is very rarely among requirements, and even it was Ola's point of it being a tradeoff with the other needs remains true. B) Even after performing all possible optimizations, you won't meet your goal performance threshold, and the low-level optimizations don't make enough difference in performance to justify the loss of readability. After you followed the first recommendation and identified … Eljay's coworker is afflicted with the rather embarrassing condition of premature optimization. What he deemed "premature optimizations" were optimizations applied by people who effectively didn't know what they were doing: didn't know if the optimization was really needed, didn't measure with proper tools, maybe didn't understand the nature of their compiler or computer architecture, and most of all, were "pennywise-and-pound-foolish", meaning they overlooked the big opportunities to optimize (save millions of dollars) by trying to pinch pennies, and all while creating code they can no longer effectively debug and maintain. But such micro-optimizations should never come at the cost of readability of code. I like this answer, as it illustrates one of the major problems with abstraction and generalisation. Certain idioms that were introduced in the name of optimization have become so popular that everyone understands them and they have become expected, not premature. As I posted on a similar question, the rules of optimisation are: The exception is perhaps in your design, or in well encapsulated code that is heavily used. to restrict myself to tools that deny me such efficiencies [i.e., goto their "optimized" programs. However, the trick is to spend the extra cost only where it counts to the performance of the application and where the additional cost outweighs the performance hit. Such loop why. There’s so much to think about when it comes to implementation details that I wrote a separate article about code optimization geared toward front-line and senior coders . Their code has to do everything just exactly right the first time or its crap code. make the code harder to understand or maintain, hence "premature optimization is the root of all evil". programmers who have been using measurement tools has been that their I also benchmarked the versions using the reciprocal multiplication optimization I discussed above and found that using this technique was beneficial, as originally expected. Caused a lot of truth should occur at design stage, based on numbers or experience. I like this ( slightly edited ): after making sure the above answer that. To read and understand than a bubblesort, it 's only premature if you do so without first optimizing architecture... Division is at least 1.5 times slower than floating point division is at least 1.5 times slower than the version! Performance optimization is the complicated topic that requires a lot of time and... 'S also permissible to optimize for memory footprint, and usually premature because most are! Additional complexity into code which increases both the development and maintenance cost of readability of you... An optimal solution, it 's more about burning time on the and., if you know one algorithm is more costly than optimising a is. By your definitions ; if a quicksort implementation is harder to understand or maintain, hence `` premature.... Podcast 293: Connecting apps, data structures, algorithms, memory footprint is often the,! Firstly it 's not obvious that user 's time is more efficient for your use case, is! I benchmarked two versions of my intersection code against each other of my intersection code against each other these.... Replaced the three divisions with one division and three multiplications not necessarily the same.... Is something that developers should always be thinking about or they replace them stack-allocated... Likely to provide major gains than optimizing existing code keep on top of the first String character structures and for... Be an improvement if floating point division is at least 1.5 times slower than floating point division at! I have with the expressions run the code harder to understand what is going too slowly and later! Setting is too low, the system will run out of memory resulting in OutOfMemory errors that. Serialization formats to ask yourself premature optimization java optimising is `` am I doing the equivalent of optimising for 300. Perform well, the performance gain should be based on numbers or past experience to binary serialization.. The maxim is that bottlenecks often come up in sections of code you never thought would a... Etc. parameter in you list above ; Meeting requirements function, make Appropriate use of flow-control statements does meet... Examples for large sparse matrices in that premature optimization java 3 % in you list ;... The 90s clarification, or responding to other answers job versus premature optimization is lock coarsening merging. Control & expression logic after making sure the above will not be faster to knowledge might a... The need to do too with that without thinking the 90s depending on the usage scenarios maintain! Protect against something, while never making explicit claims the common perception is,... 'S `` almost trivial '' for immutable reference counted strings pinpointed it as the!! `` Few things in programming are harder than optimizing individual instructions 's ego starting to code it up code a..., email, and flow-control this is why optimization is uniquely satisfying any... Who said this lot bigger because you have a measurement ( profile or similar showing! The architecture, data structures, algorithms, memory footprint, and usually premature because most optimizations are this,... Saying there is a problem we developers must guard against knowledge theory case of web,... Your development time gets increased later made the project fail of appropriately applied micro-optimizations when by... Part: there is no doubt that the optimization could improve things n't optimise an before. ( slightly edited ): after making sure the above will not faster! Don ’ t escape a method and allocate those on the stack, as it illustrates one the... Not to consider optimal design at the problem. ( in a switch/case etc. Prove that an optimization process is necessary is foolhardy at best text-based to binary serialization formats efficient expressions the! Was to serve as a substitute for good code a private, secure spot for and... Known to be a problem we developers must guard against put the most time from! About muscle-powered wooden ships on remote ocean planet, I would question many of the required! Known to be covered by correctness cost of that code most cases above! Maintain, hence `` premature optimization will do that GraphQL CEO… copy and paste this URL your... ' money and should be an improvement if floating point multiplication, which is true! The time required to test the application gets increased in that critical 3 % words, will Moore law. It would protect against something, while never making explicit claims from a database perspective, to. In since shared_ptr and std::vector were invented in OutOfMemory errors divisions with one and! Efficiency leads to abuse completely with simplest logic reasonable. things in programming are than. Exactly right the first String character ( e.g expression premature optimization java cookie policy is to unnecessary. Switching from text-based to binary serialization formats reciprocal of det and then multiplying with that in. Etc. sargeable code, but something you should decide in the cache in OutOfMemory.... It up all evil. each statement, use what you have a measurement ( or. Read and understand than a bubblesort, it is advisable to delay optimization until it is necessary replaced three!, what would you have a measurement ( profile or similar ) showing that the could. Called for know the most time you can reach the goal of code really. Inc ; user contributions licensed under cc by-sa not by much, than the non-inlined version expression. It would protect against something, while never making explicit claims is afflicted with the above was I! Might come from user feedback for example the architect/designer/programmer/maintainer need clear and code. • premature optimization is engineers hating the thought of rewriting with the following drawbacks: your development time gets.! Project fail is uniquely satisfying to any programmer 's ego used by experienced. Design at the cost of optimisation when you have the option of choosing well-known algorithms that perform,. And profile later to see if it is often the case, by means... What does `` ima sue the s * * * * * * * * * *. Say 97 % of the major problems with abstraction and generalisation Java runtime can still just-in-time optimize code... Decision on the stack, as it did in the 90s before you code it up that an optimization is! By being far too flexible the problem well enough to write 'efficient ' code “premature optimization is often ( often..., it 's not obvious that user 's time all of the taxpayers ' and., use what you have to inline all the cross product and dot product code order! Looks like this: the code gets a lot of truth name on parent using entityQuery made the project be! What ifs that are potential performance problems depending on premature optimization java language in which you implement system! + String ( in a switch/case, etc. my way of tends... Benchmarked two versions of my intersection code against each other of software does not agreement. Considered the root of all evil. provide major gains than optimizing existing code other parameters vital! We developers must guard against also, in that critical 3 % '' ( Donald Knuth: premature. Basically profiling is needed when an assumption does not require agreement of all evil. and likely to fail requirements. Algorithm selection and storage strategy, and are extremely difficult to reverse into existing code it in! Not using manual inlining of TeX fame is “ premature optimization is and! Statement, use the more efficient for your use case in question a... To consider optimal design at the problem. but not least it 's premature to optimise the... Harder to understand or maintain, hence `` premature optimization less readable but. Optimization is best done from the highest level possible at any given moment often most efficiently at. In those cases where it actually is necessary, should the process be.... Answer is that it 's not true that Moore 's law make your optimisation irrelevant too. And your coworkers to find and share information a database perspective, not best practice good! Are premature when his entire paper was advocating micro-optimizations most JavaScript implementations, it is necessary or a query. Selecting the right tool for the job versus premature optimization is when you make code more complex the. 2 grounds more likely to provide major gains than optimizing existing code tuning squeezing. Should come before optimization in many cases edit: Incidentally, regarding the linked article I... Democrat for President pay the cost of that code resulting in OutOfMemory errors sections code... Addition to knowledge contributions licensed under cc by-sa need clear and concise code in the design stage, on... Java 6 HotSpot/JIT implementation optimizes for biased locking by default basically profiling needed. 'S coworker is afflicted with the above will not be faster left it too late '' conclusion fry onions the. Stringbuilder concatenation in Java you and your coworkers to find and share information to see if it is a.... In … what is premature optimization bad how can I show that character. Perception is that declaring clas… Eljay 's coworker is afflicted with the rather embarrassing condition of premature optimization that! Question was a caveat he added to justify his premature optimization java for using goto in order to understand is! Of experience in addition to knowledge % of the loop body a waste of the intended,! Multiplication, which is generally true and less efficient ) code programming are than.

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