kandi X-RAY | Memory-Leaks Summary
kandi X-RAY | Memory-Leaks Summary
Android application featuring common memory leaks
Top functions reviewed by kandi - BETA
- Create the button
- Start the next activity
- Creates a handler which dispatches a message
- Registers a listener on the sensor
- Schedules a new timer task
- Create a new thread
- Start an async task
- Creates an inner class
- Sets the static activity
- Set the static view
- Called when the activity is created
Memory-Leaks Key Features
Memory-Leaks Examples and Code Snippets
Trending Discussions on Memory-Leaks
I am trying to use
JsonSchema to validate rows in an RDD, in order to filter out invalid rows.
Here is my code:...
ANSWERAnswered 2022-Mar-10 at 15:05
OK so a coworker helped me find a solution.
So I'm still learning about memory management in general, not only in Java. I've read in this Baeldung article.
The article shows an example of the following code:...
ANSWERAnswered 2022-Jan-27 at 09:50
You are looking at it from the wrong angle. In the end, it is not static or being a bean that determines whether the garbage collector collects an object.
The only criteria is: is that object still considered alive?!
Objects are considered alive when they can be "reached" from the context of the running thread(s).
In other words: static members are referenced by the corresponding class objects. Those in turn are (most likely) referenced by the ClassLoader that loaded the class. Therefore static members are typically alive, and won't be collected.
For your bean example, the point is: this is a method that will be invoked when an external REST request comes in. Next: request gets handled, response data gets prepared, response data is SEND out with the answer.
Now: the bean object was referenced by the response object. But after the response has been sent, there is no reference to the response any more. Thus no reference to the bean. Thus that list object is no longer alive, and list, bean, response, they all are subject to garbage collection.
But: yes, that UserController instance keeps adding User objects to that field. Thus there is a potential for a memory leak.
If the Spring frameworks discards these UserContext objects: no memory leak. If it keeps using the same object over and over again, then that list will grow, and cause a memory leak.
I am first time trying to use CRT library to detect memory leaks. I have defined
#define _CRTDBG_MAP_ALLOC at the begginging of the program. My program is made of classes one struct and main function. In main function i have
_CrtDumpMemoryLeaks(); at the end. I tried to follow these Instructions.
And I wanted to get lines where data are allocated that cause memory leaks but I get output like this:...
ANSWERAnswered 2022-Jan-06 at 15:09
Ok, It was impossible to answer my question with the information I gave(I am sorry). The problem was that I had a Base class and derived classes. And in the base class I did not have a virtual destructor. Adding virtual destructor fixed my problem and removed all memory leaks.
if i have one (or more)
CompletableFuture not started yet, and on that method(s) a few
Will the Garbage Collector remove all of that?
If there is a
get() at the end of that chain -> same question: Will the Garbage Collector remove all of that?
Maybe we need more information about that context of the join().
That join is in a Thread the last command, and there are no side-effects. So is in that case the Thread still active? - Java Thread Garbage collected or not
Anyway is that a good idea, to push a poisen-pill down the chain, if im sure (maybe in a try-catch-finally), that i will not start that Completable-chain, or is that not necessary?
The question is because of something like that? (https://bugs.openjdk.java.net/browse/JDK-8160402)
Some related question to it: When is the Thread-Executor signaled to shedule a new task? I think, when the
CompletableFuture goes to the next chained
CompletableFuture?. So i must only carry on memory-leaks and not thread-leaks?
Edit: What i mean with a not started CompletableFuture?
i mean a var I can start the notStartedCompletableFuture in that way:
Edit 2: A more detailed Example:
notStartedCompletableFuture = new CompletableFuture(); instead of a
notStartedCompletableFuture.complete(new Object); later in the program-flow or from another thread.
I can start the notStartedCompletableFuture in that way:
Edit 2: A more detailed Example:...
ANSWERAnswered 2021-Nov-20 at 23:48
If a thread calls
get() on a
CompletableFuture that will never be completed, it will remain blocked forever (except if it gets interrupted), holding a reference to that future.
If that future is the root of a chain of descendant futures (+ tasks and executors), it will also keep a reference to those, which will also remain in memory (as well as all transitively referenced objects).
A future does not normally hold references to its “parent(s)” when created through the
then*() methods, so they should normally be garbage collected if there are no other references – but pay attention to those, e.g. local variables in the calling thread, reference to a
List> used in a lambda after
According 8th step of this post I wrote following simple unit test to sure my
Test class doesn't cause memory leak:
ANSWERAnswered 2021-Nov-16 at 06:03
There are very few possibilities where this test would do something useful. All of them would involve that the constructor of
Test does some kind of registration on a global variable (either register itself on a global event or store the
this pointer in a static member). Since that is something that's very rarely done, doing the above test for all classes is overshooting. Also, the test does not cover the far more typical cases for a memory leak in C#: Building up a data structure (e.g. a List) and never clean it up.
This test may fail for a number of reasons:
GC.Collect() does not necessarily force all garbage to be cleaned. It should, but there's no guarantee that it will always happen. Also, since
testObj is a local variable, it is not yet out of scope when you call
GC.Collect(), so depending on how the code is optimized, the variable cannot be considered garbage yet, which makes the test fail.
Was trying to fix a
300MB memory-leak, and after finding leak-reason;
(Which was calls to
stringFromUTF8String:, from C++ thread (without
I edited the code, to enforce reference-counting (instead of auto-release), something like below:...
ANSWERAnswered 2021-Oct-22 at 16:26
The problem is that you're using a very short string. It's getting inlined onto the stack, so it's not released until the entire stack frame goes out of scope. If you made the string a little bit longer (2 characters longer), this would behave the way you expect. This is an implementation detail, of course, and could change due to different versions of the compiler, different versions of the OS, different optimization settings, or different architectures.
Keep in mind that testing this kind of thing with static strings of any kind can be tricky, since static strings are placed into the binary. So if the compiler notices that you've indirectly made a pointer to a static string, then it might optimize out the indirection and not release it.
In none of these cases is there a memory leak, though. Your memory leak is more likely in the calling code of
withNSString. I would mostly suspect that you're not properly dealing with the bytes passed as
chars. We would need to see more about why you think there's a leak to evaluate that. (Foundation also has some small leaks, and Instruments has false positives on leaks, so if you're chasing an allocation that is smaller than 50 bytes and doesn't recur on every operation, you probably are chasing ghosts.)
Note that this is a bit dangerous:
To detect potential memory-leaks in places where it already happened a lot I have work with tests that are build like the shown below. The main idea is to have an instance, not reference it any longer and let the garbage collector collect it. I would like not to focus on whether this is a good technique or not (in my particular case it did an excellent job) but I would like to focus on the following question:
The code below works perfectly on .NetFramework 4.8 but does not on .Net 5. Why?...
ANSWERAnswered 2021-Oct-18 at 14:26
The reason is likely tiered compilation. In simple words, tiered compilation will (for some methods under some conditions) first compile crude, low optimized version of a method, and then later will prepare a better optimized version if necessary. This is enabled by default in .NET 5 (and .NET Core 3+), but is not available in .NET 4.8.
In your case the result is your method is compiled with mentioned "quick" compilation and is not optimized enough for your code to work as you expect (that is lifetime of
myObject variable extends until the end of the method). That is the case even if you compile in Release mode with optimizations enabled, and without any debugger attached.
You can disable tiered compilation by adding:
We have a multi-threaded production Java application. We are trying to check the native memory usage as mentioned in this post.
But on the dump I am seeing 100% memory is being taken by
ANSWERAnswered 2021-Jul-08 at 12:00
Try configuring using the below flags :
I have an ASP.NET Core 3 website that is frequently running out of memory on Azure.
One of the heavy-lifting (but frequently used) functions is to generate reports. So I thought I'd use one such report as a test case to see what's going on.
Here is a memory snapshot after the application loads, and then after 9 subsequent requests for one of the reports.
Looking at the diagnostics, lots of memory is consumed by EF change tracking objects.
I've found that if I use
options.UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking); in startup, then the snapshots for the same activity produces the following:
This is a massive improvement - adding 2 MB for every request is not viable. Is this normal - I would have thought that even with change tracking on, the GC wouldn't let it get this bad? Or could there be something in my report code that is making it hold onto references or something - I read that static variables in a class can lead to the GC not freeing up those instances, is that a possibility? I'm not sure if switching off some default functionality is just a band-aid to something else I'm doing fundamentally wrong (I'm pretty sure I'm disposing everyting with
using statements, etc.).
ANSWERAnswered 2021-Jan-21 at 15:19
I would say that such outcome is expected when switching all EF queries to be
NoTracking, specially in reporting scenarios where you most likely are reading and then tracking tons of objects in memory.
In the official docs you can find detailed information about this topic. In there you can also see a benchmark comparing the performance of two queries, one that uses the change tracker and another one that doesn't, using a small data set (10 Blogs with 20 posts each). Despite the tiny amount of data, the results are similar to yours: almost a 40% increase in performance and the same-ish decrease in allocated memory.
Therefore, in regards to
I'm not sure if switching off some default functionality is just a band-aid to something else I'm doing fundamentally wrong, I would definitely say that's not a band-aid solution at all to do it just for the reporting functionality. In these read-only scenarios where you need a performance boost, using non tracking queries is actually recommended.
However, the only thing I would be aware of is that probably you don't want to switch the tracking behaviour off for ALL queries in your application. By doing so, if you rely on the change tracker to perform updates of the entities somewhere else in the application, those updates will stop working.
I'm reading a very large number of records sequentially from database API one page at a time (with unknown number of records per page) via call to
def readPage(pageNumber: Int): Iterator[Record]
I'm trying to wrap this API in something like either
Iterator[Iterator[Record]] lazily, in a functional way, ideally no mutable state, with constant memory footprint, so that I can treat it as infinite stream of pages or sequence of Iterators, and abstract away the pagination from the client. Client can iterate on the result, by calling next() it will retrieve the next page (Iterator[Record]).
What is the most idiomatic and efficient way to implement this in Scala.
Edit: need to fetch & process the records one page at a time, cannot maintain all the records from all pages in memory. If one page fails, throw an exception. Large number of pages/records means infinite for all practical purposes. I want to treat it as infinite stream (or iterator) of pages with each page being an iterator for finite number of records (e.g. less <1000 but exact number is unknown ahead if time).
I looked at BatchCursor in Monix but it serves a different purpose.
Edit 2: this is the current version using Tomer's answer below as starting point, but using Stream instead of Iterator.
This allows to eliminate the need in tail recursion as per https://stackoverflow.com/a/10525539/165130, and have O(1) time for stream prepend
#:: operation (while if we've concatenated iterators via
++ operation it would be O(n))
Note: While streams are lazily evaluated, Stream memoization may still cause memory blow up, and memory management gets tricky. Changing from
def to define the Stream in
def pages = readAllPages below doesn't seem to have any effect
ANSWERAnswered 2021-Jan-17 at 19:04
You can try implement such logic:
No vulnerabilities reported
You can use Memory-Leaks like any standard Java library. Please include the the jar files in your classpath. You can also use any IDE and you can run and debug the Memory-Leaks component as you would do with any other Java program. Best practice is to use a build tool that supports dependency management such as Maven or Gradle. For Maven installation, please refer maven.apache.org. For Gradle installation, please refer gradle.org .
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