garbage collection in java interview questions

object GC () instance method: Runtime.getruntime (). GC ();The Finalize () method has the following four characteristics:3. When the JVM executes a finalize () party of a recoverable object, it may make the object or other object reachable to a state.4. When the JVM executes the Finalize () method exception, the garbage collection mechanism does not report and the program continues execution.For most objec

threshold by controlling the object lift ratio and the reduced value. For details on all options and their related tradeoffs, check out the Java garbage collection and Java garbage Collection Essentials for Web services.We observ

Chapter Source: https://zhuanlan.zhihu.com/p/25539690Java performance optimization, sorting out an article for later restudying.JVM GC (garbage collection Mechanism)Before we learn the Java GC, we need to remember one word: Stop-the-world. It will occur in any GC algorithm. Stop-the-world means that the JVM stops executing the application because it needs to perf

(len = fis.read (buffer)) >0){Fos.write (Buffer,0,len);}}Did you find any specific reasons for this?Cause: If you upload a file using the above code, open the uploaded file to indicate that the file is being consumed by another application. But after a while, you can open it.Remember to close the input and output stream when the file is read and write, and if the input and output stream is not closed, the file is being consumed by other applications. But why, for a while,can also open the file,

The ToString () method turns it back into a string at once. Tip #5: Using a specific collection of native types The Java standard Collection library is simple and supports generics, allowing semi-static binding of types when using collections. For example, if you want to create a Set or storage map Map, this is a great way to

I have written a lot of small programs, but I still know little about memory allocation. I learned Java, and I have some basic knowledge about it, so I can write it out and forget it. For some primitive types, we call them value types. Normally, the allocated memory space is in the stack, while for the types created through new, they are in the heap. It is better to use code to explain. Public String cursor; Public int teachage; visitor = new visi

1. The core idea of garbage collection algorithmThe Java language establishes a garbage collection mechanism for tracking objects that are in use and for discovering and reclaiming objects that are no longer in use (references). This mechanism can effectively guard against t

In C + +, allocating objects on the heap is more expensive than allocating objects on the stack. The program needs to find the appropriate memory block and return the memory address. In Java, however, the garbage collector significantly increases the speed at which objects are allocated on the heap. It may sound strange, but that's how the Java

Original addressObjective See a question on Segmentfault: Java has a well-developed GC mechanism, so whether there will be a memory leak in Java, and can give a case of a memory leak. This problem view gives a complete answer to this question. Introduction to garbage collection mechanism Dur

Garbage collection is a large knowledge point in Java, but also a well-known knowledge point, after all, Java claims that its own advanced time will always take garbage collection. So it's also a regular interview, and the intervi

Recently read some articles about the garbage collection mechanism, summarize.To go back to Java garbage collection mechanism, answer from the following three aspects:1. What memory will be recovered? 2. When is it withdrawn? 3, how to recover? First, talk about which object

time, and it is appropriate to run programs in real time. However, the reference counter increases the cost of executing the program because each time the object is assigned to a new variable, the counter adds 1, and each time the existing object is scoped, the counter is reduced by 1."Java Learning materials Free Collection: tangniu520666, Notes" 4 "need to come soon"The Tracing algorithm (tracing Collec

the system (System.GC (), after which the method of the object is executed) Recycle method Area: The garbage collection of the permanent generation mainly reclaims two parts: discarded constants and useless classes. Discarded constants such as the string "ABC" entered the constant pool, the current system does not have any string object is "ABC", and there is no other place to refer to the literal, when th

improve the scalability of Java applications.Finally, a very simple example of a tracking collector is posted so that you can deepen your understanding of the collector:Trace collector LegendWhere to pay attention to using the garbage collectorHere are some things to note about the garbage collector, the garbage colle

this almost unique method of knowing how the JVM garbage collector works in a production environment. The generally acceptable GC overhead is capped at 5%, which is trivial if you know the cost of the system for GC pauses and can take action to minimize the cost.Conclusion: In the capacity range, as much as possible to obtain the system in the production environment of the operational data, you will find that it is a new world.SummarizeHopefully the

A, who is doing garbage Collection? A popular saying: in C + +, the system is doing garbage collection, and in Java, Java itself is doing. In C + +, freeing the memory is handled manually, using the delete operator to free the a

, and almost all objects are allocated in that region. Java heap is the main area of memory recovery, from the perspective of memory recovery, because the current collectors are mostly using generational collection algorithm, so the Java heap can be subdivided into: the new generation and the old age, then subdivide a point can be divided into Eden space, from Su

Objective See a problem on the Segmentfault: Java has a perfect GC mechanism, then in Java will be a memory leak problem, and can give a memory leak case. The full answer to this question is given in the view of this question. Introduction to garbage collection mechanism In the process of running a program, each obj

phase can also be done concurrently with the user program, but because only a portion of the region is reclaimed, time is user-controllable, and a pause in the user thread will significantly improve collection efficiency. Has the following characteristics: Spatial integration: As a whole, a collector based on the "mark-and-organize" algorithm, from a local (two region), is based on the "copy" algorithm, which means that no memory space

74.12 of the data in the O zone.View the Java Virtual machine memory situation, or use this command: Java-statHere are the principles, thanks to http://jefferent.iteye.com/blog/1123677 here for easy viewing, you can also directly copy the URL on his blog to viewThe total of the virtual machines is divided into three generations: young Generation, Old Generation, and persistent (Permanent Generation). The p