Develop Reference

How to find battery leak in my application?

I've written an application, it's a big one and it has lots of features.
But I have a problem with it: in the phone battery usage it takes about 35 percent of battery and it's a huge problem even when I don't use it very much.
I've no services in my application and I really don't know where the problem is.
Is there any way that I can find out what is using my battery?

I am using PowerTutor for this purpose when i am testing my application performance and battery usage. Even i am using this application also https://developer.qualcomm.com/software/trepn-power-profiler. Please try this let me know if it helps you.

Java runtime check [duplicate]

I need to optimise a Java application. It makes some 3rd party calls. I need some good tool to accurately measure the time taken by individual API calls.
To give an idea of complexity-
the application takes a data source file containing 1 million rows, and it takes around one hour to complete the processing. As a part of processing , it makes some 3rd party calls (including some network calls). I need to identify which calls are taking more time then others, and based on that, find out a way to optimise the application.
Any suggestions would be appreciated.

I can recommend JVisualVM. It's a great monitoring / profiling tool that is bundled with the Oracle/Sun JDK. Just fire it up, connect to your application and start the CPU-profiling. You should get great histograms over where the time is spent.
Getting Started with VisualVM has a great screen-cast showing you how to work with it.
Screen shot:
Another more rudimentary alternative is to go with the -Xprof command line option:
-Xprof
Profiles the running program, and sends profiling data to
standard output. This option is provided as a utility that is
useful in program development and is not intended to be be
used in production systems.

I've been using YourKit a few times and what quite happy with it. I've however never profiled a long-running operation.
Is the processing the same for each row? In which case the size of the input file doesn't really matter. You could profile a subset to figure out which calls are expensive.

Just wanted to mention the inspectIT tool. It recently became completely open source (https://github.com/inspectIT/inspectIT). It provides complete and detailed call graph with contextual information, there are many out-of the box sensor for database calls, http monitoring, exceptions, etc.
Seams perfect for your use-case..

Try OPNET's Panorama software product

It sounds like a normal profiler might not be the right tool in this case, since they're geared towards measuring the CPU time taken by the program being profiled rather than external APIs that it calls, and they tend to incur a high overhead of their own and collect a large amount of data that would probably overwhelm your system if left running for a long time.
If you really need to collect performance data over such a long time, and mainly for external calls, then Perf4J is probably a better tool.

In our office we use YourKit profiler on a day to day basis. It's really light weight and serves most of the performance related use cases we have had.
But I have also used Visual VM. It's free and fast. You may first want to give Visual VM a try before going towards YourKit (YourKit is not freeware).

visualvm (part of the SDK) and Java 7 can produce detailed profiling.

I use profiler in NetBeans (it is really brilliant and already built in, no need to install plugin) or JVisualVM when not using NetBeans.

Memory build up in a java program GapContent$MarkData

I am currently developing an application that need to be very fast executing about every 20ms (yeah I know, should not have taken Java in the first place). I worked a lot optimizing the code so it would not be too computation greedy. However, as I have seen I may have not put enough effort in GUI and memory optimization. My application can run at the speed I want but after 1-2 minutes it drastically slowdown suggesting a memory problem.
I did run the profiler under NetBeans and found out that most of the memory was taken by the javax.swing.text.GapContent$MarkData
And searched on google, I saw mostly nothing understandable helping me with that problem. So is there anyone that could help me? My first guess would be that the garbage collector doesn't run long enough to erase unused object...but I don't have more clue than that.

You are right to employ profiling; now use Profile > Profile Project > CPU to find and target the hot spot(s).
The slowdown was due to a function that closed and opened a connection with the database each iteration.
Consider using SwingWorker to query the database in the background and process() results on the event dispatch thread, as shown in this related example.

What you are calling a "Memory build up" is only 600Kb. If this 600Kb is problematic I question your choice of Java and Swing.
I have an application that sometimes generates hundreds of megabytes of log messages.
I'm guessing your GUI application is somewhat similar. The app probably has a JTextPane that displays a log. As the app runs it adds messages to the JTextPane.
The Document implementation used by JTextPane is a PlainDocument.
Even though you probably always insert new log messages at either only the top or only the bottom, the PlainDocument implementation is general-purpose. It supports modification anywhere in the document by putting a gap in the underlying stream of text and then putting the changes into the gap. As the app inserts new messages into the Document it creates lots and lots of Gaps.
The actual text to display has to exist somewhere. There is probably a better way to implement a huge text pane, but the default JTextPane will look, to the profiler, like a memory leak. If you have 600kb of log messages, its going to take at least 600kb of memory somewhere.

You should know that the Java Console uses a PlainDocument with GapContent$MarkData and just having the console open with lots of data in it will cause this "memory leak" to appear. Clear the console to see the number of MarkData drop back to acceptable levels.

Is Logging using FileHandler a bottleneck?

I am considering logging business events in a J2EE web application by using Java logging and FileHandler.
I am wondering whether that could cause a performance bottleneck, since many log records will be written to one file.
What are your experiences and opinions?
Is logging a busy web application to one file with Java logging and FileHandler likely to become performance bottleneck?

It all depends on how much log statements you add. If you add logging after every line of code then performance will must certainly degrade.
Use logging for the important cases, set the correct logging level for your current purposes (testing or actual deployment) and use constructions like
if (Logger.isDebugEnabled()) {
Logger.debug("Value is " + costlyOperation()")
}
to avoid calling code that is costly to run.
You might also want to check this article

In order to avoid generalities like "it depends" or "a little" etc. you should measure the performance of your application with and without the logging overhead. Apache JMeter can help you generate the load for the test.
The information you can collect through logging is usually so essential for the integrity of the application, that you can not operate blindly. There is also a slight overhead if you use Google Analytics, but the benefits prevail.
In order to keep your log files within reasonable sizes, you can always use rotating log files.

I think that JavaRevisited blog has a pretty good post on a problem with performance: Top 10 Tips on Logging in Java

In a recent project, I log audit events to a database table and I was concerned about performance, so I added the ability to log in 'asynchronous' mode. In this mode the logger runs in a low-priority background thread and the act of logging from the main thread just puts the log events onto a queue which are lazily retrieved and written by the background logging thread.
This approach will only work, however, if there are natural 'breaks' in the processing; if your system is constantly busy then the queue will never be emptied. One way to solve this is to make the background thread more active depending on the number of the log messages in the queue (an enhancement I've yet to implement).

You should:
Define an appropriate metric of performance (e.g., responsiveness, throughput, etc.). Then you should measure this metric with all logging turned off and then on. The difference would be the cost of logging.
Then you should experiment with different logging libraries and the modes they provide and document the observed differences.
In my personal experience, for all the three projects I worked on, I found that asynchronous logging helped improve the application throughput a lot. But the same may not hold for you, so make sure you make your decision after careful measurements.
The following does not directly relate to your question.
I noticed that you specifically mentioned business logging. In this case, you may also want to keep logging relevant and clean, in case you find your log files are growing huge and difficult to understand. There is a generally accepted design pattern in this area: log as per function. This would mean that business logging (e.g., customer requested a refund) goes to a different destination, interface logging would go to another destination (e.g., user clicked the upvote button != user upvoted an answer), and a cross system call would go to another destination (e.g., Requesting clearance through payment gateway). Some people keep a master log file with all events as well just to see a timeline of the process while some design log miners/scrappers to construct timelines when required.
Hope this helps,

I'm asked to tune a long starting app into a short time period

I'm asked to shorten the start-up period of a long starting app, however I have also to obligate to my managers to the amount of time i will reduce the startup - something like 10-20 seconds.
As I'm new in my company I said I can obligate with timeframe of months (its a big server and I'm new and I plan to do lazy load + performance tuning).
That answer was not accepted I was required to do some kind of a cache to hold important data in another server and then when my server starts up it would reach all its data from that cache - I find it a kind of a workaround and I don't really like it.
do you like it?
What do you think I should do?
PS when I profiled the app I saw many small issues that make the start-up long (like 2 minutes) it would not be a short process to fix all and to make lazy load.
Any kind of suggestions would help.
Language is Java.
Thanks

Rule one of performance optimisation: measure it. Get hard figures. At each stage of optimisation measure the performance gain/loss/lack of change. You (and your managers) are not in a position to say that a particular optimisation will or will not work before you try it and measure it. You can always ask to test & measure a solution before implementing it.
Rule two of performance optimisation (or anything really): choose your battles. Please bear in mind that your managers may be very experienced with the system in question, and may know the correct solution already; there may be other things (politics) involved as well, so don't put your position at risk by butting heads at this point.

I agree with MatthieuF. The most important thing to do is to measure it. Then you need to analyze the measurements to see which parts are most costly and also which resource (memory, CPU, network, etc) is the bottleneck.
If you know these answers you can propose solutions. You might be able to create small tests (proof of concepts) of your solution so you can report back early to your managers.
There can be all kind of solutions for example simply buying more hardware might be the best way to go. It's also possible that buying more hardware will have no results and you need to make modifications. The modifications can be optimizing the software, the database or other software. It might be to choose better algorithms, to introduce caching (in expense of more memory usage) or introduce multi threading to take advantage of multiple CPU cores. You can also make modifications to the "surroundings" of your application such as the configuration/version of your operating system, Java virtual machine, application server, database server and others. All of these components have settings which can affect the performance.
Again, it's very important to measure, identify the problem, think of a solution, build solution (maybe in proof of concept) and measure if solution is working. Don't fall in to the trap of first choosing a solution without knowing the problem.

It sounds to me as if you've come in at a relatively junior position, and your managers don't (yet) trust your abilities and judgment.
I don't understand why they would want you to commit to a particular speed-up without knowing if it was achievable.
Maybe they really understand the code and its problems, and know that a certain level of speed-up is achievable. In this case, they should have a good idea how to do it ... so try and get them to tell you. Even if their ideas are not great, you will get credit for at least giving them a try.
Maybe they are just trying to apply pressure (or pass on pressure applied to them) in order to get you to work harder. In this case, I'd probably give them a worth-while but conservative estimate. Then spend some time investigating the problems more thoroughly. And if after a few days research you find that your "off the cuff" estimates are significantly off the mark, go back to the managers with a more accurate estimate.
On the technical side, a two minute start-up times sounds rather excessive to me. What is the application doing in all that time? Loading data structures from files or a database? Recalculating things? Profiling may help answer some of these questions, but you also need to understand the system's architecture to make sens of the profile stats.
Without knowing what the real issues are here, I'd suggest trying to get the service to become available early while doing some of the less critical initialization in the background, or lazily. (And your managers' idea of caching some important data may turn out to be a good one, if viewed in this light.) Alternatively, I'd see if it was feasible to implement a "hot standby" for the system, or replicate it in such a way that allowed you to reduce startup times.