shareMySoftwareExperience()

How to add nameservers in Ubuntu

2012-10-23T01:16:00.001-07:00

Ubuntu (I dont exactly know on which version its started to do so ) overwrites manual changes made to resolv.conf. Here is what you can

sudo vi /etc/resolvconf/resolv.conf.d/tail

Enter the below nameservers:

nameserver 10.34.34.221
nameserver 10.34.34.222

and run

resolvconf -u

Done.

while IFS='|' read -r

2012-09-23T04:31:00.002-07:00

I really fancy the performance achieved while reading a stream line by line using file separator IFS and read -r option. For example assume you have a phone list like the below:

NAME SURNAME PHONE
john|smith|+44.............
ali|veli|+90..........

...

carlos|suarez|+34..............

You can process the file with the below script line by line having name surname and phone numbers separated.

cat phonelist | while IFS="|" read -r V1 V2 V3; do echo "Name:$V1 Surname:$V2 Phone:$V3";done

Its really fast compared to reading line by line and using awk for processing the lines.

2012-01-23T10:50:00.003-08:00

Is MySQL usage really declining?

2012-01-23T10:50:00.001-08:00

Is MySQL usage really declining?

Be aware HP or other brand Network Printer holders.

2012-01-09T04:33:00.001-08:00

http://boingboing.net/2011/12/30/printer-malware-print-a-malic.html

2012-01-04T10:47:00.001-08:00

FuseOverAmazon - s3fs - FUSE-based file system backed by Amazon S3 - Google Project Hosting

2011-11-15T08:20:00.001-08:00

5 Apache Hadoop Use Cases

2011-11-15T08:19:00.001-08:00

Anonymous Post: Don't Use MongoDB

Viva open source

2011-10-14T09:21:00.001-07:00

Are There More Acquisitions to Come From Google?

Open source software for building private and public clouds

2011-10-10T22:47:00.000-07:00

Worth looking at. Led by very strong companies, collobration is high and license is Apache!

http://www.openstack.org/

Best Practices for Scaling Java Applications with Distributed Caching

2011-10-02T22:22:00.001-07:00

Best Practices for Scaling Java Applications with Distributed Caching

Yet another build system...

2011-09-29T22:45:00.001-07:00

buildr — Apache Buildr

Microsoft Says It Will Give Your Data to the U.S

2011-06-30T22:27:00.001-07:00

Microsoft Says It Will Give Your Data to the U.S. Government, Even If It's Not in the U.S.

List of Tools for REST Web Services in Java | Javalobby

2011-06-30T08:30:00.001-07:00

List of Tools for REST Web Services in Java | Javalobby

Blogger available for android

2011-06-29T08:17:00.001-07:00

And this is my first test

Information about Red-Hat 32-bit kernels from Memory Management Perspective

2011-06-02T01:07:00.000-07:00

Until today Red-Hat had support for 3 types of kernels no-smp,, smp (pae) and hugemem kernels. Of these 3 kernels hugemem kernel was released for Red-Hat 3 and 4 versions but dropped after that. I will explain the reason I found for that below but first of all lets try to understand the need for hugemem kernel. Lets look at the limitations of kernels:

NO-SMP kernels, memory space usage
* Generally 16MB DMA, 896MB low memory and rest is high memory.
* Max supported phy. memory is 4GB

1.0 GB Text/code
1.7 GB available process memory for mmap, malloc / address space
(e.g. usable by shared Pool)
0.3 GB Stack
1.0 GB Kernel space (all low memory + some portion of high memory)

SMP kernels, memory space usage is same as NO-SMP except that the total mem is increased upto

* Still 16MB DMA, 896MB low memory and rest is high memory.
* Max supported phy. memory is 64GB. Although 16GB is recommended; this is because kernel-space should know and hold reference for user-space resources and because of this when user-space usage increases over 16GB the kernel space's starts to consume all the low memory part thus OOM killer tries to kill user-space processes to free up space in the kernel space and the system can fall into a hang state finally.
* CPU's address extension and kernels pae support together provide more User space for the processes but kernel space and memory space partitioning

1.0 GB Text/code
1.7 GB available process memory for mmap, malloc / address space
(e.g. usable by shared Pool)
0.3 GB Stack
1.0 GB Kernel space

Hugemem kernels, memory space usage
* It is memtioned that low memory configuration changed but I could not find a definite number yet. As far as the kernel space increased upto 4GB 4 times larger than before low memory should also have been increased. If I can find a hugemem kernel installed I will cat /proc/meminfo
* Hugemem kernel support was introduced in RedHat 3-4 but droped later. This is because highmem patches were never accepted upstream. The guys in the Red Hat team assumed that 64bit architecture is wide spreading and the hugemem effort to cure the 32+4 bit architecture sickness should not be carried on.

1.0 GB Text/code
2.7 GB available process memory for mmap, malloc / address
space (e.g. usable by shared Pool)
0.3 GB Stack
4.0 GB Kernel

Conclusion:
So if you take a look at the official Red Hat Enterprise Linux Technology capabilities and limits page you will see that max phy memory support drops 16GB from 64GB for Redhat 5 and later on 32-bit architecture. You should remember that 64GB still possible for SMP PAE kernel but dangerous for consuming kernel resources and bringing the system in a hang state.

Remember that 64-bit arch treats all memory as low memory and memory limit is theoretically upto 8TB and practically 250GB-1TB for linux kernels. And I think its important to align the development strategies for 32-bit or 64-bit with RedHat teams strategic decisions; if you are developing software for this platform.

rsync with ssh for resumable scp behaviour

2011-05-09T13:43:00.000-07:00

Dont you get annoyed when you have a fragile vpn or internet connection to a site where you are trying to download a large file via scp and the transfer is broken on the half way or even when you are about to finish %99 lol.

So this happened to me these days so I discovered rsync with ssh option to continue downloading from where just the download was interrupted.

sudo rsync --partial --progress --rsh=ssh username@ipaddress:/path_to_file /path_to_target_folder

If you have a different port than default ssh port

sudo rsync --partial --progress --rsh='ssh -p12321' username@ipaddress:/path_to_file /path_to_target_folder

Note: This also works after when scp transfer was broken. You still continue to download from where you remained.

How to extend a Virtual Box Image Hard Disk Size

2011-04-18T13:27:00.000-07:00

1-) Use clonezilla latest.iso and boot from Virtual Machine the iso.

2-) Copy the source disk to target disk with Expert mode and k1 mode selected which is for scaling up the existing virtual disk to target virtual disk.

3-) When finished open the virtual machine with a latest gparted.iso image.

4-) Enter the commmand line mode and pvscan the virtual hard disk and Note your virtual harddisk path such as /dev/sda2

5-) sudo pvresize /dev/sda2 This is done for resizing the outer LVM2 type Virtual Disk partition.

6-) lvscan to discover internally mapped virtual ext3 or ext2 linux partitions such as /dev/mapper/virtual-disk-name

7-) sudo lvresize -L /dev/mapper/virtual-disk-name This will extend your inner mapped linux partition.

8-) resize2fs /dev/mapper/virtual-disk-name This will resize the filesystem.

Robolectric: Test-Drive Your Android Code

2011-03-24T13:06:00.000-07:00

What does Roboelectric do?

Graph Visualization tool for Ant makefiles.

2011-03-05T06:37:00.000-08:00

I recommend Grand as a graph visualization tool for Ant files.

Reach from here

Tips for installing memcached on Red-Hat 4

2011-01-17T07:23:00.000-08:00

1-) web access :)

2-) rpm -ihv ftp://ftp.pbone.net/mirror/ftp.pramberger.at/systems/linux/contrib/rhel4/archive/x86_64/libevent-1.3e-4.el4.pp.i386.rpm

3-) rpm -ihv htp://ftp.pbone.net/mirror/ftp.pramberger.at/systems/linux/contrib/rhel4/archive/i386/memcached-1.4.5-1.el4.pp.i386.rpm

Dont install memcached 1.2 versio0n and the stupid libevent 1.3b beta release than you will get EAGAIN resource temporyliy unavailable erro when trying to asyncroushly write to memcached server.

Our Coreopsis Rota Video Monitoring Deprecated Latest release

2011-01-11T14:10:00.000-08:00

We stopped developing the Coreopsis Project on 2007. This is the latest release of our Windows Based Ip Camera management system (2007). From the below link download Setup1_05.zip. Only Windows XP Windows 2000 and Windows 2003 servers are supported. The software is for free....

http://code.google.com/p/barisergunexperimentalstuff/downloads/list?can=1&q=

Memcached Performance Tests and Source Code (Java Source, Ant Project)

2010-12-22T05:56:00.000-08:00

What is Memcached?

I have prepared some test cases in order to test the performance of Memcached distributed caching library. You can get them from my code repository with the following mercurial script.

hg clone https://barisergunexperimentalstuff.googlecode.com/hg/ barisergunexperimentalstuff

For your information if you don't have a mercurial rep client than you can get it with your favorite package manager. I use "sudo apt-get install tortoisehg" on my Ubuntu.

A-) Local tests:

Local tests are done with a sample DataObject. when you run the tests 8 different memcached instances are started on 8 consequent ports.

Steps to follow

- Install memcached (eg. sudo apt-get install memcached). On my previous post I also have information about on installing memcached on Centos 5.5

- Then, run tests with below ant script

ant local.test -Dentry.count=10000 -Dttl=60

Dentry.count is used to configure number of objects to cache. Dttl is used to configure TTL for each object in the cache.

A-) Distributed tests:

Local tests automatically starts and terminates the memcached servers on local machine. For distributed tests you will have to start the memcached servers on remote machines and give the server_ip:server_port combinations with a specific format as shown below.

Steps to follow:

- Install memcached on remote servers

- Start memcached servers.

Eg:

memcached -d -u root -m 1024 10.34.3.13 -p 1121

- Run distributed tests with following arguments(just a sample)

ant distributed.test -Dentry.count=10000 -Dget.timeout=10 -Dttl=300 -Dservers="10.34.3.11:1121 10.34.3.12:1121 10.34.3.13:1121"

Dget.timeout is for timeout for reading from cache
Dservers is list of memcached servers.

Tips for installing memcached on Centos 5.5

2010-12-22T01:12:00.000-08:00

1-) Get the below memcached rpm file

wget ftp://ftp.pbone.net/mirror/ftp.pramberger.at/systems/linux/contrib/rhel5/i386/memcached-1.4.5-2.el5.pp.i386.rpm

My architecture was i386 you find yours an get the appropriate one.

2-) rpm -ihv memcached-1.4.5-2.el5.pp.i386.rpm

There you go....

Performance of inserting data on Jboss Cache compared to ConcurrentHashMap.

2010-12-14T04:19:00.000-08:00

You can use the below Beanshell script directly with the Jboss Cache 3.2.5 GUI Demo with embedded Beanshell. Just copy the below code piece to a file eg trial.bsh. And to run it from the embedded Beanshell of JBoss Cache GUI Demo do -> source("trial.bsh"). You should see some tps and performance related text output. The below beanshell script file is for ENTRY_COUNT = 120000; You can play with different number of entries. Also do not forget to play with Xms arguments not to get a stack overflow for large entries.


import org.jboss.cache.Fqn;
import java.util.Date;
import java.io.*;
import java.util.concurrent.ConcurrentHashMap;
import java.lang.instrument.*;



public class LocationDataObject implements Externalizable {

 private static final long serialVersionUID = 3383966388917008053L;

 private Double xCoord;
 private Double yCoord;
 private  Date timeStamp;

 public Double getXCoord(){
  return xCoord;
  
 }
 public Double getYCoord(){
  return yCoord;
 }
 public Date getTimeStamp(){
  return timeStamp;
 }

 public void setXCoord(Double xCoord){
  this.xCoord =xCoord ;
  
 }
 public void setYCoord(Double yCoord){
  this.yCoord = yCoord;
 }
 public void setTimeStamp(Date timeStamp){
  this.timeStamp = timeStamp;
 }

 
        public void readExternal(ObjectInput in) 
        throws IOException,ClassNotFoundException {

            xCoord = in.readDouble();
            yCoord = in.readDouble();
            timeStamp = (Date)in.readObject();
        }

        
        public void writeExternal(ObjectOutput out) 
        throws IOException {
            out.writeDouble(xCoord);
            out.writeDouble(yCoord);
            out.writeObject(timeStamp);
        }

};



public class TestJbossCachevsHasmap{
 private static final Long ENTRY_COUNT = 120000;

    private static Instrumentation instrumentation;

    public static void premain(String args, Instrumentation inst) {
        instrumentation = inst;
    }


 public static void main(String [] args){

  childFqn1 = Fqn.fromString("/Msisdn");

  tm = cache.getTransactionManager();

  tm.begin();
  msisdnMap = root.addChild(childFqn1);
  tm.commit();

  locData = new LocationDataObject();

  Long startTime = System.currentTimeMillis ();

  for(Long fakeMsIsdn=0; fakeMsIsdn < ENTRY_COUNT; fakeMsIsdn++){

   locData.setXCoord(10.00D);
   locData.setYCoord(20.00D);
   Date dateNow = new Date();
   locData.setTimeStamp(dateNow);
 
   tm.begin();
   msisdnMap.put(fakeMsIsdn.toString(), locData);
   tm.commit();
 
  }

  Long endTime = System.currentTimeMillis ();

  Long executionTime = (endTime - startTime);

  double tps = (ENTRY_COUNT*1000)/executionTime;

  System.out.println("Duration of Jboss Cache for inserting " + ENTRY_COUNT + " entries in " +  executionTime + " msec. Average tps is " +tps );

  //System.out.println(ObjectSizeFetcher.getObjectSize(root));

  concurrentMap = new ConcurrentHashMap ();

  Long startTime2 = System.currentTimeMillis ();

  for(Long fakeMsIsdn=0; fakeMsIsdn < ENTRY_COUNT; fakeMsIsdn++){


   locData.setXCoord(10.00D);
   locData.setYCoord(20.00D);
   Date dateNow = new Date();
   locData.setTimeStamp(dateNow);
   concurrentMap.put(fakeMsIsdn.toString(), locData);
 
  }

  Long endTime2 = System.currentTimeMillis ();

  Long executionTime2 = endTime2 - startTime2;

  double tps2 = (ENTRY_COUNT*1000)/executionTime2;

  System.out.println("Duration of ConcurrentHashMap for inserting " + ENTRY_COUNT + " entries in " +  executionTime2 + " msec.  Average tps is " +tps2 );


 }

    public static long getObjectSize(Object o) {
        return instrumentation.getObjectSize(o);
    }
 


}


TestJbossCachevsHasmap.main(null);