I go through some tutorials of Java Profilers (JVisualVM, JProfiler, YourKit) on Youtube as well as Pluralsight. I got a little bit idea regarding how to check heap-dump and how to find the memory leak. But these all tutorials are elementary.
My query is, when I analyse in heap-dump, I saw only 3 types of objects char[], java.lang.String and java.lang.Object[] which covers almost all memory(more than 70% always). But none from my application.
And the same way for thread dump, I saw HTTP-8080 request (the port I am using) and that leads me to Runnable()'s run method or Java Concurrent Package and again not to any specific code to my project.
I also discussed the problem with some of my friends and analyse their application as well (which doesn't face any issues regarding memory leak and performance), but their results are almost the same.
Would you guys help to understand how to analyse heap-dump and thread-dump in JVisualVM for the large scale application? Any video, blog, anything would be helpful.
I am using OpenJDK-11, AWS ECS-Docker and Tomcat as a web-server.
Checkout the Eclipse Memory Analyzer (https://www.eclipse.org/mat/), I used it in the past several times to successfully find memory leaks, but it takes some time to get familiar with it.
Another advise I can give you is to create benchmark tests with Apache JMeter (https://jmeter.apache.org/) or another tool that lets you reproduce the performance/memory issue and identify the execution path that cause you problems.
Be aware AWS doesn't like when someone execute performance/penetration tests against their services (https://aws.amazon.com/aup/)
Related
I'm currently migrating the Fragaria framework from a GC-only environment to GC being supported. After the work was done (or what I thought had to be done to make it work) I was able to run the examples that come with the framework without any problems and Instruments didn't show any major memory leaks.
I included non-GC Fragaria in my non-GC application and it crashes as soon as I place the cursor on it. To be honest the usage pattern is different from the examples as I'm embedding it in an instance of NSViewController instead of NSDocument.
Can you give me some tips on how to debug this? I'm a bit lost on where to proceed now.
First thing to do is Build and Analyze the code, then fix any problems it finds.
Next, try running with Zombie detection enabled (google NSZombie).
Finally, each crash's stacktrace should give you a pretty good idea where things have gone off the rails.
Where can I find the code for creating an online rebol console like the one here ?
http://tryrebol.esperconsultancy.nl/
Update: for the sandbox system on the server, can't Rebol manage it itself with some security wrapper and its security options ?
As for console itself, I don't know Ruby so I don't want to use TryRuby and why would I need it ? Can't I mimic Rebol console itself by "remoting" it somehow ? Why RT or Esper Consultancy can't make an opensource version ? There's no value in keeping it closed source. Rebol needs to prove it's more open than in the past.
In my opinion, you should aim higher with something like the already open-sourced Try Ruby. You'd type in expressions and it would guide you. Their showcase site is at tryruby.org and is fairly slick.
I modified TryRuby to work with Rebol and it wound up looking like this:
But I'm not going to run it on my server because I didn't want to belabor the necessary sandboxing/etc. or protections against someone running an infinite loop. I can give you what I've got so far if you want it.
I started a tutorial script here that no one seemed interested in helping me with, so I wandered off to other tasks:
http://www.rebol.net/wiki/Interactive_tutorial_script
I'm not sure what exactly you want. You mention you want a remote REBOL shell instead of a tutoring setup, but that's what the Try REBOL site is. There are several reasons it's not open source:
It's in heavy development. I'm currently changing the code regularly.
So it's not in a release state. Preparing it for release, documenting and publishing it would take a lot of extra work, as with most projects.
It's written in my CMS that's also in heavy development. Even if the Try REBOL site were open source, it wouldn't run. The CMS is not planned to be open sourced soon.
It's not meant as a generic REBOL remoting tool, but as a one-off demo site. If that site is running, what's the use of more of them?
As others have answered, there are many generic solutions for remoting that you could use. Also, most parts of the Try REBOL site are readily available as open source:
Syllable Server, produced and published by us.
The Cheyenne web server.
The HTML source of the web client can be viewed, including my simple JavaScript command service bus.
Syllable Server is an essential part of the site, as the sandboxing is not done with REBOL facilities (except some extra limits in the R3 backend), but with standard Linux facilities.
A truly air tight (do I mean silica tight?) sandbox is close to impossible with R2.
R3 (still in alpha) is looking a lot more promising. The deep technical discussions in flight right now (see Cure code and AltME/REBOL3 Proposals regarding unwinds and protect and even occasionally mentioning sandboxes should lead to an excellent sandbox capability.
Right now, the big advance R3 has that makes Kaj's tryREBOL possible is R3's secure policy settings which make it possible (with some careful wrapper code) to construct an alpha/demo sandbox.
To answer your precise question("where can I find code...", you could try asking Kaj for his :)
I'm new to StackOverflow. I'm not sure if this is going to end up as a reply to your comment, or as a new answer.
The somewhat common idea that any project can be open sourced and contributed to by others is a naive view. In the case of my Try REBOL site, it makes no sense. It's not just in heavy development; it's written in a CMS that's also in heavy development. Basically noone could contribute to it at this point, because I'm the only one who knows my CMS. Or in any case its newest features, which I develop by developing Try REBOL, and other example sites. So developing Try REBOL means developing the CMS at the same time, and by definition, I'm the only one who can do that.
More generally, my projects are bleeding edge, innovative technology with a strong vision. The vision is mine, and to teach it to others, I have to build it to show how I intended it to work. So there's a catch 22: to enable others to contribute, I have to finish my projects first, because people typically don't understand them until I show them how they work.
There certainly are other projects where mass contribution makes more sense. Still, only the top projects get the contributors. We found that out the hard way. We created Syllable Desktop and Syllable Server with surrounding infrastructure for contributions. These are fairly classic, well understood operating systems that many people could work on in parallel. However, despite years of begging, we get very few contributions.
So, if you feel a burning need to contribute to our projects, please pick one of the many tasks in Syllable to execute. :-)
I'm looking for a code coverage tool that I can use with a BlackBerry application. I'm using J2ME-Unit for Unit Testing and I want to see how much of my code is being covered by my tests.
I've tried using Cobertura for J2ME but after days of wrestling with it I failed to get any results from it. (I believe that the instrumentation is un-done by the RAPC compilation). And despite this message, the project seems to be dead.
I've looked at JInjector but the project seems very incomplete. There is little (if any) documentation and although it claims to be able to work with BlackBerry projects, I haven't seen any places where it has been used for that purpose. I've played with the project quite a bit but to no avail.
I've also tried the "Coverage" view in the BlackBerry JDE, even though I use Eclipse for development. The view stays permanently blank, regardless of clicking "Refresh" and running the application from the JDE.
I've looked at most of the tools on this SO thread, but they won't work with J2ME/BlackBerry projects.
Has anyone had any success with any code coverage tools on the BlackBerry? If so, what tools have you used? How have you used them?
If anyone has managed to get JInjector or Cobertura for J2ME to work with a BlackBerry project, what did you have to do to get it working?
I can't speak for Coberatura or JInjector, because I don't know how they collect test coverage probe data.
What is
critical is how this data is captured (does it need Java runtime support only available in standard Java VMs?) and how it is exported to the test coverage display/report generation tools.
Our SD Java Test Coverage tool instruments your source code; at runtime this produces an array of native Java booleans representing the coverage data, without need for any special VM support. Normally, this array is exported directly to a file, used by the test coverage display mechanism, by a TCVDump method provided with the test coverage tool, as your application exits.
Java (and other programming langauges used) in embedded systems often requires custom methods to extract the test coverage data. You might need to code a special dump procedure (in Java) to write out that boolean array to an accessible place. Our experience with building such custom dump procedures is that they are generally pretty simple (a few dozen lines); the real trick is deciding how/where to put the data, so that it can be easily moved to the target file. Mostly this is just a peculiar pair of copies, the first of which copies the boolean array to some staging location, and the second which writes the staged data into the destination file. (The standard TCVdump method is provided in source form to enable this kind of customization).
While I haven't specifically looked at BlackBerry, if you can write the data anywhere, you can pretty much be assured you can achieve this. We've had success with other embedded hand-set systems, such as Symbian, doing this.
If you want a complete overview of how to generally instrument code for test coverage following this strategy, see this paper: Branch Coverage for Arbitrary Languages Made Easy
I was actively involved with JInjector while working at Google. We were able to use it to successfully obtain code coverage for Blackberry applications. The application lifecycle for Balckberry apps is less predictable than J2ME and we found we had to tweak the application code to ensure the coverage data was gathered. I didn't personally work on the blackberry apps, several other engineers did. I'd hoped we'd create an example blackberry application and make it available on the jinjector site, but events and life got in the way.
If you would be willing to provide a sample blackberry apps with some unit tests, I'd be willing to spend a few hours trying to help you get the code coverage working. I'm not actively working with either J2ME or Blackberry (I'm currently working on Android apps when I have time to experiment with mobile) so I'm quite rusty. I have a day job that doesn't involve much mobile test automation, however I continue to work on ways to improve the test automation for mobile apps e.g. http://code.google.com/p/mwta/downloads/list for Android Test Automation.
I'm julianharty at gmail.com
I am getting Out of Memory errors in classic ASP, probably where attempting to access data. For example:
Microsoft VBScript compilation error '800a03e9'
Out of memory
(some file) Line 0
These errors only happen once in a while and they keep happening for a few minutes and then the webserver must be restarting the app pool because all sessions are lost.
What is a good tool for finding/diagnosing memory leaks in a classic ASP application that makes heavy use of ADO for data access and a couple of other off the shelf COM objects.
Presumably any memory leaks would be from the COM object rather than the script, so a general Windows debugger or leak finder might be what I need. Any advice on what would be appropriate?
Or any other thoughts on what might cause these errors?
Unfortunately, tracking down memory leaks is not an easy task :-(
Here's a good summary of things to watch out for here:
http://www.leinadium.com/code/classic-asp-memory-leaks-in-iis/
Be sure to read the link inside that post as well for a list of tools.
Good luck!
Microsoft has a good utility umdh.exe that may be good for finding leaks in this situation. It allows you to take a "snapshot" at one point, exercise the application (e.g., IIS) then take another snapshot and compare the memory usage differences.
if
you try to get one row data with EOF OR BOF
or
the database connection is close or readony you try to wirte!
you should get the ERROR.
I've used the CF Remote Performance Monitor, however this seems to only track memory initialised in the managed world as opposed to the unmanaged world. Well, I can only presume this as the numbers listed in the profiler are way short of the maximum allowed (32mb on CE 5). Profiling a particular app with the RPM showed me that the total usage of all the caches only manages to get to about 12mb and then slowly shrinks as (I assume) something unmanaged starts to claim more memory.
The memory slider in System also shows that the device is very short on memory. If I kill the process the slider shows all the memory coming back. So it must (?) be this managed process that is swallowing the memory.
Is there any simple(ish?) fashion how one can track unmanaged memory usage in some way that might enable me to match it up with the corresponding P/Invoke calls?
EDIT: To all you re-taggers it isn't .NET, tagging the question like this confuses things. It's .NETCF / Compact Framework. I know they appear to be similar but they're different because .NET rocks whereas CF is basically just a wrapper around NotImplementedException.
Try enabling Interop logging.
Also, if you have access to the code of the native dll you are using, check this out: http://msdn.microsoft.com/en-us/netframework/bb630228.aspx
I've definitely been fighting with unmanaged issues in a C# managed app for a while -- it's not easy.
What I've found to be most helpful is to have a regular output to a text log file. For example you can print the output of GlobalMemoryStatus every couple of minutes along with logging every time you load a new form. From there you can at least see that either memory gradually erodes, or a huge chunks of memory disappeared at specific times of the day.
For us, we found a gradual memory loss all day as long as the device was being used. From there we eventually found that the barcode scanning device was being initialized for no particular reason in our Form base class (I blame the previous developer! :-)
Setting up this logging may be a small hassle, but for us it paid huge dividends in the long run especially with the device in live use we can get real data, instrumentation, stack traces from exceptions, etc.
Ok, I'm using C++ on CE, not C# so this may not be helpful, but...
I use a package called Entrk toolbox which monitors memory and resource usage, leaks, and exceptions under Windows CE. Pretty much like a lightweight CE version of boundschecker. Does the trick most times.