Java how fast

While Java programs are compiled directly, Python is interpreted which slows down Python programs during runtime. Determining the variable type which occurs during runtime increases the workload of the interpreter. Also, remembering the object type of objects retrieved from container objects contributes to memory usage.

In Python, any bugs introduced by the programmer will not be found until that line of code is triggered. This can risk operational breakdowns and extend turnaround time.

Java speed test code is Java-specific code used to test the responsiveness and performance of a website, application, or server as part of a regular review or to determine whether optimization is necessary.

A speed test provides at least these three data points:. This is a simple way to boost the speed of your Java applications without any change in the code logic. Lists, ArrayLists, and Vectors have a contains method that allows programmers to check if a collection already has a similar object. You may be iterating through a large sample and, very often, you may need to find a list of unique objects in the sample.

Your code might look like this:. Functionally, this code is fine, but from a performance standpoint, you are checking whether the ArrayList contains the object on every iteration of the loop.

The contains method scans the entire ArrayList each time. So, as the ArrayList gets bigger, the performance penalty increases. You will be better off adding all the samples to the ArrayList first, conducting a duplicate check once, using a collection such as a HashSet that inherently provides uniqueness, and creating the unique ArrayList once. Instead of having potentially s of contains checks on the ArrayList, now you have a one-time duplicate check. As you can see above, the savings from the performance tweaks we made increases as the size of the ArrayList being accessed increases.

When your application is dealing with larger data sets, the importance of performance tuning is more. Java developers have been taught to use Hashtables and HashMaps when dealing with key value pairs and to use a collection like a LinkedList, ArrayList, Vector, etc.

When you have a large list and you need to search this list, you have to use the contains method of the List object. Consider the code snippet below:. The table below summarizes the performance difference between the two approaches as the list size increases:.

I have been with Java since the beginning, so from my point of view the fame of being slow was created by non-responsive and slow GUI frontends AWT, and then Swing and in Applets probably because of the additional slow startup times of the VM's. Java has stipulated and promoted a lot of research in the VM area, and there have been quite some improvements, including the garbage collection you can tune a lot of things actually; however, often I see systems where only defaults are used and hotspot optimization which at the beginning and probably still is more efficient on the server side.

Java at the backend and the computational level is not that slow. Colt is one of the best examples:. The latest stable Colt release breaks the 1. There are many things outside mainstream Java that should be considered, like Realtime Java or special mechanisms to enhance the speed like Javolution , as well as Ahead-Of-Time compilation like gcj.

However, there are many other languages for the Java VM nowadays e. Personally I continue to enjoy it as a flexible and reliable platform, with excellent tooling and library availability, that allows one to work with everything from the smallest device e.

JavaCard to the largest servers. A hammer is much slower at rolling out dough than many other tools. Doesn't make the hammer "slower", nor less useful for the tasks that it is designed to do. As a general programming language, Java is on par with many if not most for a wide array of programming tasks. There are specific, trivial tests for which Java will not outperform hand-coded solutions in less sophisticated languages, ones that are "closer to the metal". But when it comes to "real world applications", Java often is the Right Tool.

Now, that said, nothing will stop developers from making a slow-performing solution using ANY tool. However, Java's mostly clean design and syntax does do a lot to reduce misuse. Java is a high-level language and its reputation nowadays is to have performance on par with other, comparable high-level languages.

It has dynamic binding semantics. But it's also a cleaner, more high-level semantic. I do not remember the details, but I heard in the early days of Java that there was a mutex per Java object, to be acquired and released by each method.

That tends to make it better adapted to concurrency, although unfortunately just a mutex per object will not protect you from races or deadlocks or any of the bad things that can happen in concurrent programs.

That part, if true, is a little naive, but it came from good intentions. Feel free to fill me in on the details if you know more about this aspect.

Another way in which Java is a high-level language is by having Garbage-Collection. Garbage-Collection may be slower than malloc and free for programs that allocate at once all the memory they need and work with that.

The problem is, in languages that do not have Garbage-Collection, programmers tend to write only programs that allocate all the memory they need at once and fail if it turns out some arbitrary maximum size constant has been overflown. So the comparison is apples to oranges. When programmers make the effort to write and debug programs with dynamic allocation of chained structures in non-GC languages, they sometimes find that their programs are no longer faster than in a GC language, because malloc and free are not free!

They have overhead too Plus, not having a GC forces to specify who frees what, and having to specify who frees what in turn sometime forces you to make copies — when several functions are going to need the data and it's not clear which will be using it last — whereas copying wouldn't have been necessary in a GC language. Many Java desktop apps these times: things like Eclipse have bad GUI responsiveness, probably due to the high memory consumption and the fact that classloader can do lots of IO.

It's improving but was worse few years ago. Many most people like to do generalizations so they say "Java is slow" because they perceive the apps are slow when they interact with them. The major problem with java applications is that it is huge due to the large size of the stock runtime library. Huge programs fill a lot in memory and tend to swap, meaning they become slow. The reason the Sun JVM is large is because it has a very good byte code interpreter which works by keeping track of a lot of things.

That means much data, which means memory. You may want to look at the jamvm virtual machine which is an reasonably fast interpreter no native code and very small. It even starts up fast. As Pascal says, Java is on par with other high-level languages. However, as someone who worked with the original JVMs on Windows 98 , at the time the level of abstraction provided by the Java virtual machine was, shall we say, painful.

Basically, it was software emulation with little or no optimization that we take for granted today in the JVM.

People normally trot out the "it's interpreted" line. Because once upon a time, it was, and bad press gets handed down by people who dumped Java as 'too slow' and never returned to test newer versions. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Is Java really slow? Ask Question. Asked 11 years, 9 months ago. Active 6 years, 3 months ago. Viewed 82k times. Stefano Borini Stefano Borini k 92 92 gold badges silver badges bronze badges.

I wonder if a question like "why bubble sort is slow" would obtain the same result. I asked a technical question, and wanted technical answers which I got , but closing the question as subjective and argumentative is ridiculous.

I have read most of the top comments and none of them seem to address the glaring fact that C GUI-based desktop applications run much faster than any Java GUI-based desktop applications, including modern ones. As a client-side web dev who has dealt with.

I suspect the real problem isn't benchmarks but rather the issue of there simply being a crap-ton of mediocre Java devs out there. That's not the language's fault. It's not the fault of Java devs who actually hone their craft and learn languages other than Java. It may however be the fault of Sun, certs, the '90s, and the IT industry in general. Active Oldest Votes. However, there are several places where Java is faster than most other languages: Memory allocation and de-allocation are fast and cheap.

JIT compilation took time to become efficient major improvements with each version Classloading has become a lot more efficient over the years.

It used to be quite inefficient and slow during startup. Swing and UI code did not use native graphics hardware very well. Swing is just awful. Heavy use of synchronization in library classes; unsynchronized versions are now available Applets take forever to load, because of transmitting a full JAR over the network and loading the VM to boot. Synchronization used to carry a heavy performance penalty this has been optimized with each Java version. Reflection is still costly, though.

Peter Mortensen 29k 21 21 gold badges 97 97 silver badges bronze badges. You can do much better still if you write your own memory handlers with things like free lists, memory pools, and so on or use a library that implements such. Rex Kerr - Why use memory handlers if you can use e. You are confusing heap memory allocation with object instantiation. Sjoerd - Where did I say that everything in Java is faster?

Just read what I said. I said what I meant, and have already addressed everything you said in your last comment. Show 14 more comments.

From the people I've talked to the impression of Java being slow comes from two things: Slow VM startup time.