Write a short note on garbage collection and compaction meaning

This is a very personal and subjective opinion of mine, but I believe that a person well versed in GC tends to be a better Java developer. If you are interested in the GC process, that means you have experience in developing applications of certain size. If you have thought carefully about choosing the right GC algorithm, that means you completely understand the features of the application you have developed.

Write a short note on garbage collection and compaction meaning

Sustainability, Resource Depletion

Other Extensions Introduction The Common Lisp standard allows considerable latitude in the details of an implementation, and each particular Common Lisp system has some idiosyncrasies. This chapter describes ordinary user-level features of Clozure CL, including features that may be part of the Common Lisp standard, but which may have quirks or details in the Clozure CL implementation that are not described by the standard.

It also describes extensions to the standard; that is, features of Clozure CL that are not part of the Common Lisp standard at all.

Memory-mapped Files In release 1. On operating systems that support memory-mapped files including Mac OS X, Linux, and FreeBSDthe operating system can arrange for a range of virtual memory addresses to refer to the contents of an open file.

As long as the file remains open, programs can read values from the file by reading addresses in the mapped range. Using memory-mapped files may in some cases be more efficient than reading the contents of a file into a data structure in memory.

Clozure CL provides the functions map-file-to-ivector and map-file-to-octet-vector to support memory-mapping. These functions return vectors whose contents are the contents of memory-mapped files. Reading an element of such a vector returns data from the corresponding position in the file.

Without memory-mapped files, a common idiom for reading the contents of files might be something like this: It differs in that the above example creates a new vector in memory and copies the file's contents into it; using a memory-mapped file instead arranges for the vector's elements to point to the file's contents on disk directly, without copying them into memory first.

The vectors returned by map-file-to-ivector and map-file-to-octet-vector are read-only; any attempt to change an element of a vector returned by these functions results in a memory-access error. Clozure CL does not currently support writing data to memory-mapped files.

Vectors created by map-file-to-ivector and map-file-to-octet-vector are required to respect Clozure CL's limit on the total size of an array. That means that you cannot use these functions to create a vector longer than array-total-size-limit, even if the filesystem supports file sizes that are larger.

4/26/2004 News: YV12 is b0rked

The value of array-total-size-limit is expt 2 24 on but platforms; and expt 2 56 on bit platforms. If successful, the function maps the file's contents to a range of virtual addresses.

If successful, it returns a read-only vector whose element-type is given by element-type, and whose contents are the contents of the memory-mapped file.

Specified as a type-specifier that names a subtype of either signed-byte or unsigned-byte.


Because of alignment issues, the mapped file's contents start a few bytes 4 bytes on bit platforms, 8 bytes on bit platforms into the vector. The displaced array returned by map-file-to-ivector hides this overhead, but it's usually more efficient to operate on the underlying simple 1-dimensional array.

Given a displaced array like the value returned by map-file-to-ivectorthe function array-displacement returns the underlying array and the displacement index in elements.

write a short note on garbage collection and compaction meaning

Currently, Clozure CL supports only read operations on memory-mapped files. If you try to change the contents of an array returned by map-file-to-ivectorClozure CL signals a memory error. The value of a static variable is thus the same across all threads; changing the value in one thread changes it for all threads.

Static variables are shared global resources; a dynamic binding is private to a single thread. Static variables therefore provide a simple way to share mutable state across threads.

They also provide a simple way to introduce race conditions and obscure bugs into your code, since every thread reads and writes the same instance of a given static variable.Garbage Collection, Lecture Notes - Computer Science - Prof Jonathan pfmlures.com, Computer Science, University of California, USA, Prof.

Jonathan Shewchuk, Computer Science, Garbage Collection, Roots and Reachability, Mark and Sweep Garbage Collection, Memory Addresses.

write a short note on garbage collection and compaction meaning

Understanding Memory Management pausetime, which optimizes the garbage collector for short and even pause times. depending on the garbage collection mode used.

Debugging ART Garbage Collection | Android Open Source Project

Compaction is performed at the beginning of or during the sweep phase and while all Java threads are paused. contamination of air, water, or soil by substances that are harmful to living organisms.

Pollution can occur naturally, for example through volcanic eruptions, or as the result of human activities, such as the spilling of oil or disposal of industrial waste.

Supported. In the context of Apache HBase, /supported/ means that HBase is designed to work in the way described, and deviation from the defined behavior or functionality should be reported as a bug. Realm Java is the first database built for mobile.

An alternative to SQLite and ORMs that's fast, easy to use, and open source. * NUES. The student will submit a synopsis at the beginning of the semester for approval from the departmental committee in a specified format. The student will have to present the progress of the work through seminars and progress reports.

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