what's the overhead when allocating objects/arrays in Java?

Posted by Gnijuohz on Programmers See other posts from Programmers or by Gnijuohz
Published on 2012-08-28T03:15:59Z Indexed on 2012/08/28 3:51 UTC
Read the original article Hit count: 282

Filed under:

java

|

memory

How many bytes an array occupies in Java? Assume It's a 64bit machine and also assume there are N elements in an array, so all these elements would take up 2*N, 4*N or 8*N bytes for different types of array.

And a lecture in Coursera says that it would occupy 2*N+24, 4*N+24 or 8*N+24 bytes for a N element array and the 24 byte is called overhead, but didn't explain it.

Also objects have overheads, which is 16 bytes.

What exactly are these overheads? Also, do these overheads only exist in Java? How about C, C++ and Python?

© Programmers or respective owner

Related posts about java

Tomcat 6: Access Control Exception?

as seen on Server Fault - Search for 'Server Fault'
I'm trying to setup a tomcat6 server, and I'm trying to match another setup someone else established. However, my deployment (default Ubuntu install) uses a policy.d/ directory structure, and the established server just uses a catalina.policy file. I've tried setting every entry in policy.d to match… >>> More
Problem in creation MDB Queue connection at Jboss StartUp

as seen on Stack Overflow - Search for 'Stack Overflow'
I am not able to create a Queue connection in JBOSS4.2.3GA Version & Java1.5, as I am using MDB as per the below details. I am putting this MDB in a jar file(named utsJar.jar) and copied it in deploy folder of JBOSS, In the test env. this MDB works well but in another env. [ env settings and… >>> More
failing to establish connection between Postgres db and gwt

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am using Postgres and gwt 2.0 for one of my applications. I am facing problem connecting to the database. When I try to connect it gives "ClassNotFoundException". Here is what I get when I try to connect to database: java.lang.ClassNotFoundException: org.postgresql.Driver at java.net… >>> More
failing to establish connection between postgre db and gwt

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, For i am using postgre and gwt 2.0 for one of my applications. I am facing problem connecting to the database. When i try to connect it gives "ClassNotFoundException". Here is what i get when i try to connect to database: java.lang.ClassNotFoundException: org.postgresql.Driver at java.net… >>> More
Migration and deployement problems JBoss 4.2.2.GA to JBoss 6.0.0.M2

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I'm trying to migrate an application running on JBoss 4.2.2.GA to JBoss 6.0.0.M2 I give you some log to explain my problem : boot.log : 2010-03-16 09:59:29,406 ERROR [org.jboss.system.server.profileservice.ProfileServiceBootstrap] (Thread-2) Failed to load profile: Summary of incomplete deployments… >>> More

Related posts about memory

SQL Server and Hyper-V Dynamic Memory Part 2

as seen on SQL Blog - Search for 'SQL Blog'
Part 1 of this series was an introduction and overview of Hyper-V Dynamic Memory. This part looks at SQL Server memory management and how the SQL engine responds to changing OS memory conditions. Part 2: SQL Server Memory Management As with any Windows process, sqlserver.exe has a virtual… >>> More
SQL Server and Hyper-V Dynamic Memory - Part 1

as seen on SQL Blog - Search for 'SQL Blog'
SQL and Dynamic Memory Blog Post Series Hyper-V Dynamic Memory is a new feature in Windows Server 2008 R2 SP1 that allows the memory assigned to guest virtual machines to vary according to demand. Using this feature with SQL Server is supported, but how well does it work in… >>> More
SQL Server and Hyper-V Dynamic Memory - Part 1

as seen on SQL Blog - Search for 'SQL Blog'
SQL and Dynamic Memory Blog Post Series Hyper-V Dynamic Memory is a new feature in Windows Server 2008 R2 SP1 that allows the memory assigned to guest virtual machines to vary according to demand. Using this feature with SQL Server is supported, but how well does it work in… >>> More
Python Memory leak - Solved, but still puzzled

as seen on Stack Overflow - Search for 'Stack Overflow'
Dear everyone, I have successfully debugged my own memory leak problems. However, I have noticed some very strange occurence. for fid, fv in freqDic.iteritems(): outf.write(fid+"\t") #ID for i, term in enumerate(domain): #Vector tfidf = self.tf(term… >>> More
SQL Server and Hyper-V Dynamic Memory Part 3

as seen on SQL Blog - Search for 'SQL Blog'
In parts 1 and 2 of this series we looked at the basics of Hyper-V Dynamic Memory and SQL Server memory management. In this part Serdar looks at configuration guidelines for SQL Server memory management. Part 3: Configuration Guidelines for Hyper-V Dynamic Memory and SQL Server Now that… >>> More