6500 strict priority queue size ???

Hi guys,
Is it possible to adjust the 6500 line cards strict priority queue size? Most cards assign 85% of thebandwdith to the oridinary queues and 15% to the strict priority queue. It seems that it is not possible to adjust the size of the strict priority queue.
I have a customer who has numerous T1's encapsulated into IP and the gross amount of traffic is about 200Meg, all of which is real time. If I were to mark this as DSCP 46 (COS 5) it would saturate the strict priorty queue leading not only to performance problems on the T1's but would also starve the rest of the traffic on the 1Gig WAN link.
Any thoughts guys?
Regards, Steve

Hi Paresh,
Thanks for your reply. I think I didn't explain myself properly. There is a bandwidth allocation of memory for each port. The priority queue gets 15%by default. I have so much priority queue traffic that I want to increase this to 25% because all of it is strict priority (its voice after all). If this canot be done then I will be losing packets of voice since the priorty queue will not be able to accomdate the amount of traffic.
Best regards, Steve

Similar Messages

7600 QoS Strict-Priority

Hello,
I'm testing in a LAB QoS configuration for 7600 (SUP720-3B) with 12.2-18.SXF3 with many diffenents cards.
Following Cisco documentation, I have two diferent scenarios:
1. OSM and WAN interfaces supports CBWFQ and LLC and it works fine, as I understand it should work. We could create a priority queue and many standard queues to clasify the traffic and assign differents BW.
2. LAN interfaces don't support CBWFQ and LLC and we should use the Queue Architecture of the card and WRR and WRED, which are implemented on the ASICs. This is what Cisco calls Hardware-Switched Traffic.
Here it depends of the card you use what Queue Architecture you could use. But most cards have a Strict-Priority Queue and one or more standard queues.
My question is regarding about the diferent behavior of the priority queue (LLC) and the Strict-Priority queue in case of congestion on the interface.
From my testings I got:
+ 1st scenario (Priotity Queue - LLC)
In case of congestion of the interface, QoS provide to the Priority Queue just the BW configured. If the BW offered in this queue is higher than the BW configured, there're packet drops.
The rest of the standard queues shares the rest of the BW available on the interface.
+ 2nd scenario (Hardware-Switched Traffic)
Even with or without congestion, I get almost the same behavior. The router always try to transmit the traffic of the strict-priority queue first. So it doesn't matter how much BW you allocate to the strict-priority queue and the standard queues. The card always try to transmit the traffic of strict-priority queue first.
Is this the desired behavior or there's something wrong?
The behavior of the priority queue should be the same in both scenarios?
I got the following answers from Cisco Web Site which doesn't answer my question completely (See attached file).
Anyone tried this before???
Thanks.
Paco

Hello Baley,
Thanks for your reply. I read this link before but it doesn't explain exactly what happens in the scenario described before.
Few days ago I got an answer from Cisco which confirms what I read from the FAQ: Till Strict-Priority Queue isn't empty, packets on the WRR queues aren't send. This behavior is completely different from the well known LLQ.
Catalyst 6500/6000 QoS FAQ
Q. On egress queuing, if the strict priority queue is saturated, will traffic eventually be served in the weighted round-robin (WRR) queues?
A. No, the WRR queues are not served until the priority queue is completely empty.

Does the priority queue always work?

Hi
I have a 8Mbp of wan link which sometime gets saturated and I have shaped average this to 8Mbps but i am running vocie on this WAN link and have defined priority for voice with 850kbps under voice class. My question is when the link is not fully utilized, Will the packets from priority queue are always dequeued first as compared to packets sent from from other queus or will the QoS will not do anything here since the link utilization is lot less than what is sepecified in shape average. I am asking this to confirm if the priority queue always help to overcome the issue of jitter if either the link is saturated or not?
Thanks

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Posting
You describe PQ and shaping, but the former is usually a part of doing QoS on L2/L3 switches, and the latter on routers. What device(s) and their IOS versions and the WAN media are you working with?
On "routers", interfaces generally have FIFO tx-rings, only when they overflow, are packets placed in CBWFQ queues. Within CBWFQ, LLQ will be dequeued first, but such packets might have already been queued behind other non-LLQ traffic within the interface tx-ring. (NB: for routers, with tx-rings, when supporting VoIP, you may want to minimize the size of the tx-ring.)
Shapers, in my experience, are "interesting". First, I believe many shapers don't account for L2 overhead, but provider CIRs often do. So unless you shape slower than the nomimal CIR rate, you can send faster than the available bandwidth. (Often I've found shaping 10 to 15% slower allows for average L2 overhead.)
Second, shapers work on averages over time intervals. For VoIP, you'll often want to insure the shaper is using a small Tc, otherwise it will allow FIFO bursts. (I've found a Tc of 10ms seems to support VoIP fairly well.)
Third, I suspect some shapers might have their own queues between the interface and the defined policy queues. If they do, unknown what their queuing organization is or their supported queuing depths. If this is the case, makes it difficult to engineer QoS.
Whenever possible, I've found it beneficial to work to avoid using shapers especially for timing sensitive traffic, like VoIP. In your case, I would suggest, if possible, obtaining 10 Mbps of WAN bandwidth and somewhere passing the traffic through a physical 10 Mbps interface, with a QoS policy.
But to more directly answer your question, PQ (or LQ) will dequeue its packets next compared to other "peer" queues. This should always help VoIP for delay and jitter, but there's more involved whether this is necessary and/or whether it's helpful enough when necessary.
You ask about when a link is saturated, but a link is 100% saturated everytime a packet is being transmitted. Often link usage is represented in percentages of usage of possible maximum transmission rate over some time period, but when it comes to QoS, 100% utilization might be just fine while 1% utilization is not. Much, much more information, about your situation, might be needed to offer truly constructive recommendations.

Priority Queues

hi iam a beginner in java, could you please help me with this code. thanks
Implement (provide complete Java code) a priority queue using a singly linked list. You may call this class LinkedPriorityQueue. The use of classes contained in the Java Collections framework in the above implementing is strictly forbidden.
You may need to write a second class, PQNode, which defines the nodes in your linked list. Feel free to implement the PQNode class in anyway that you see fit. However, the LinkedPriorityQueue class should implement all methods and constructors

Here is the search of the forums
http://search.java.sun.com/search/java/index.jsp?qp=&nh=10&qt=%22singly+linked+list%22&col=javaforums&x=23&y=16
Here is a google search
http://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&q=%22singly+linked+list%22+java
Due tomorrow???

D-ary heap with Priority Queue implementation

I have to construct a program that find the k-th smallest integer in a given set S of numbers; read from the standard input a first line containing positive integers N, k, and d separated by spaces. Each of the following N lines contains a positive integer of the set S. I have to implement a generic d-ary heap class that implements all methods of the priority queue interface.
i have the following code...but the inserting bubbling doesnt seem to wokr right...
any help would be great:
import java.util.*;
public class Heap {
    static Element[] heap;
    int N;
    static int k;
    int d;
    static int size = 0;
    Compare comp;
    public Heap(int nodes, int max, Compare c)
        N = max;
        d = nodes;
        heap = new Element[N];
        comp = c;
    public static void main(String args[])
        Scanner _scan = new Scanner(System.in);
//      String Nkd = _scan.nextLine();
   //     Scanner _scanNkd = new Scanner(Nkd);
        int _N = 0;
        int _d = 0;
        Compare _c = new Compare();
            _N = _scan.nextInt();
            k = _scan.nextInt();
            _d = _scan.nextInt();
        Heap _heap = new Heap(_d,_N,_c);
        int i=0;
        int num=0;
        while(_scan.hasNextLine()&&num<_N)
            System.out.println("test" + _scan.nextInt());
            _heap.insert(i, _scan.nextInt());
            i++;
            size++;
            num++;
        for(int z=0;z<_N;z++)
        //    System.out.println(heap[z].getKey());
        Element kth = null;
        for(int j = 1; j <=k; j++)
            kth = _heap.removeMin();
        System.out.print(kth.getKey());
        System.out.print('\n');
        /*System.out.print(k);
        System.out.print('\n');
        System.out.print(_heap.size());
        System.out.print('\n');
        System.out.print('\n');
        System.out.print(heap[0].getKey());
        System.out.print('\n');
        System.out.print(heap[1].getKey());
        System.out.print('\n');
        System.out.print(heap[2].getKey());
        System.out.print('\n');
        System.out.print(heap[3].getKey());
        System.out.print('\n');
        System.out.print(heap[4].getKey());
        System.out.print('\n');
        System.out.print(heap[5].getKey());*/
    public void insert(int i, int e)
        heap[i] = new Element(e,i);
        this.bubbleUp(heap);
public int size() {return size;}
public boolean isEmpty() {return(size == 0);}
public int min(){return heap[0].getKey();}
public Element remove()
int i = size-1;
size--;
return heap[i];
public Element removeMin()
Element min = this.root();
if(size == 1)
this.remove();
else
this.replace(this.root(), this.remove());
this.bubbleDown(this.root());
return min;
public Element replace(Element a, Element b)
a.setIndex(b.getIndex());
a.setKey(b.getKey());
return a;
public void bubbleUp(Element e)
Element f;
while(!e.isRoot(e.getIndex()))
f = this.getParent(e.getIndex());
if(comp.compare(f,e) <= 0)
break;
else
int temp = f.getIndex();
f.setIndex(e.getIndex());
e.setIndex(temp);
swap(f,e);
System.out.println("bubbling");
e=f;
public void bubbleDown(Element e)
int i = e.getIndex();
while(e.isInternal(i, size))
Element s;
if(!e.hasRight(i, size))
s = this.getLeft(i);
else if(comp.compare(this.getLeft(i), this.getRight(i)) <= 0)
s = this.getLeft(i);
else
s = this.getRight(i);
if(comp.compare(s,e) < 0)
swap(e,s);
e = s;
else
break;
public void swap(Element x, Element y)
int temp = x.getIndex();
x.setIndex(y.getIndex());
y.setIndex(temp);
public Element root() {return heap[0];}
public Element getLeft(int i) {return heap[i*2];}
public Element getRight(int i) {return heap[i*2+1];}
public Element getParent(int i) {return heap[i/2];}
class Element
private int key;
private int index;
public Element(int k, int i)
key = k;
index = i;
public int getKey() {return key;}
public void setKey(int k) {key = k;}
public int getIndex() {return index;}
public void setIndex(int i) {index = i;}
public boolean isRoot(int i) {
if (i == 0)
return true;
else
return false;
//return i == 1;
public boolean hasLeft(int i, int size) {return 2*i <= size;}
public boolean hasRight(int i, int size) {return 2*i+1 <= size;}
public boolean isInternal(int i, int size) {return hasLeft(i, size);}
public boolean isExternal(int i, int size) {return !isInternal(i, size);}
class Compare implements Comparator<Element>
public Compare(){}
public int compare(Element a, Element b)
int x=0;
if(a.getKey() < b.getKey())
x = -1;
else if(a.getKey() == b.getKey())
x = 0;
else if(a.getKey() > b.getKey())
x = 1;
return x;

Well, this might be a swifty thing to do, unfortunately the Java Dudes in their infinite wisdom decided that asynchronous servlets were a bad thing. I disagree mind you. So while you could do what you wanted, you still have all these threads hangin' out waiting for their work to be done, which is just really lamo.
Anyhoo, to do this, just add a reference to the socket in the entry class, and when you pick up an entry from the heap, you can fetch the socket again, and send the results back to that socket. Of course you're probably going to moof up session info, and timeouts et. cetera, but it might work.

Implemeting a priority queue

Hi all,
i have written a priority queue which implements a priority queue interface however i'm getting a liitle stuck. I'm pretty new to Java programming, i'm trying to write a hosptial simulation where ill people arrive and are given a priority to be seen by a medic.
Every patient that is added to the queue has an int prioriy and the patient that is serviced next is the one with the highest priority. There are three priorities, low, medium, high. If more than one patient has the same highest priority, the patient with that priority that has been longest in the queue will be serviced.
Could you please help me out to see where my mistakes are?
Thanks
The priority queue interface
import java.util.Iterator;
public interface PriorityQueue
* Adds element to the priority queue
* @param element - the element to be added to the queue.
public void add (Priority element);
* Removes the next element from the priority queue
* Precondition: size() != 0
public void remove ();
* The next element to be serviced. This is the element in the queue that has
* the highest priority. If more than one element has the highest priority,
* the one which was added to the queue earliest is returned.
* Note that this has no effect on the queue - you must call remove as well to
* change the queue state.
* Precondition: size() != 0
* @return the next element to be serviced.
public Priority next();
* @return the number of elements in the priority queue
public int size();
* @return an Iterator for the priority queue.
public Iterator iterator
The priority queue
import java.util.ArrayList;
import java.util.Iterator;
public class PriorityQueueImpl implements PriorityQueue
private final static int DEFAULT_PRIORITY_COUNT = 3;
private ArrayList elements = new ArrayList();
public void add (Priority element)
elements.add (element);
public void remove ()
Iterator it = elements.iterator();
it.remove();
public Priority next()
Iterator it = elements.iterator();
Priority p, highestPriority;
while (it.hasNext())
p = it.next();
if (p.priority > highestPriority.priority)
highestPriority = p;
else if (p.priority == highestPriority.priority &&
p.admissionTime < highestPriority.admissionTime)
highestPriority = p;
public Iterator iterator()
Iterator it = new Iterator()
int size = size();
int priority = priority;
return it;
public int size()
int size = 0;
if (queue[i] !=null)
size += queue.size();
return size;

Hi there,
I guess you are on the Herts uni course like myself, right? Have you had any luck with getting this to work, or are you still stuck like me?!
cheers
Matt Brett

Generic priority queue

i have to make a priority queue that uses generics. i already had written a priority queue, and making the key, which was a Comparable, generic was easy, but i don't know how to do it for the data, which is an object. If someone could tell me how that'd be great. here is my code:
public class PriorityQueue<K>{
private int size;
Node first;
//Post: A class to store data, key and next to be used in the PriorityQueue
protected class Node{
Comparable key;
Object data;
Node next;
Node(Comparable k, Object d, Node n){
key = k;
data = d;
next = n;
//Post: Creates an empty queue.
PriorityQueue(){
first = new Node(null, null, null);
//Pre: size() >= 1
//Post: returns the highest priority data item
public Object peekData(){
return first.next.data;
//Pre: size() >= 1
//Post: returns the highest priority key
public Comparable <K> peekKey(){
return first.next.key;
//Post: Inserts the data into the queue at the correct spot based on
// priority determined by its key
public void insert(Comparable <K> key, Object data){
Node newNode = new Node(key, data, null);
Node current = first;
          size++;
while(current.next != null && (newNode.key.compareTo(current.next.key)) > 0){
current = current.next;
newNode.next = current.next;
current.next = newNode;
//Pre: size() >= 1
//Post: Deletes the highest priority key and data item
public void remove(){
first.next = first.next.next;
size--;
//Post: returns the number of elements in the queue
public int size(){
return size;
}

Pretty much as Stefan says. Here's some code:
public class PriorityQueue<K extends Comparable<K>, D> {
private int size;
private Node first;
// Post: A class to store data, key and next to be used in the PriorityQueue
protected class Node {
    K key;
    D data;
    Node next;
    Node(K k, D d, Node n) {
      key = k;
      data = d;
      next = n;
// Post: Creates an empty queue.
PriorityQueue() {
    first = new Node(null, null, null);
// Pre: size() >= 1
// Post: returns the highest priority data item
public D peekData() {
    return first.next.data;
// Pre: size() >= 1
// Post: returns the highest priority key
public K peekKey() {
    return first.next.key;
// Post: Inserts the data into the queue at the correct spot based on
// priority determined by its key
public void insert(K key, D data) {
    Node newNode = new Node(key, data, null);
    Node current = first;
    size++;
    while (current.next != null
           && (newNode.key.compareTo(current.next.key)) > 0) {
      current = current.next;
    newNode.next = current.next;
    current.next = newNode;
// Pre: size() >= 1
// Post: Deletes the highest priority key and data item
public void remove() {
    first.next = first.next.next;
    size--;
//Post: returns the number of elements in the queue
public int size() {
    return size;
}

Priority Queue using Vector

I am trying to develop Priority Queue using vector. For inserting elements I need to check if the inserted objects have greater key I want to shift them. In short, I want to store objects in vector in sorted manner (sort by key). I need help for that.
The code I have created so far is like this:
import PriorityQueue;
import java.util.*;
import java.io.*;
public class PQItem
     private Object e;
     private int k;
     public PQItem(int key, Object element)
          k=key;
          e=element;
     public int key(){ return k;}
     public Object elelment(){ return e;}
     public void setkey(int key){k=key;}
     public void setElement(Object element){e=element;}
     public static void main(String args[])
          FileReader fr;
          fr = openfile();
     public static FileReader openfile()
          String line,name,file="test.txt";
          int vsize,k1,i1=0;
          boolean flag;
          Object e1,e2;
          //Vector v = new Vector();
          PriorityQueue q=new PriorityQueue();
          try
               FileReader fr=new FileReader(file);
               BufferedReader inFile = new BufferedReader(fr);
               String del=",";
               line=inFile.readLine();
               StringTokenizer tokenizer=new StringTokenizer(line,del);
               while(line!=null)
                    tokenizer = new StringTokenizer(line,del);
                    k1 = Integer.parseInt(tokenizer.nextToken());
                    e1 = tokenizer.nextToken();
                    //System.out.println(line);
                    q.InsertItem(line,i1);
                    line=inFile.readLine();
                    i1++;
               flag=q.isEmpty();
               System.out.println(flag);
               vsize=q.size();
               System.out.println(+vsize);
               e2=q.last();
               System.out.println(e2);
          }//try
          catch(FileNotFoundException exception)
               System.out.println("The File "+file+" was not found");
          catch(IOException exception)
               System.out.println(exception);
          return null;
     }//filereader
//The other file is
import java.util.*;
public class PriorityQueue
     private Object[] a;
     Vector v = new Vector();
     //Constructor
     public PriorityQueue()
     public int size() {return v.size();}
     public boolean isEmpty() { return (v.size())==0;}
     public void InsertItem(Object e,int k)
          v.insertElementAt(e,k);
          //new code
          //for(int i=0;i<size;i++)
     public Object last()
          return v.lastElement();

Why not let Java do the work - use a java.util.TreeSet instead of a Vector.
Make your PQItem implement Comparable, write a compareTo(Object o) method (and an equals method for completeness) and you're golden. Then when you add(pqItem) it goes in the exact spot it belongs.

Priority Queue add help?

ok, I'm making a priority queue from a List and I'm trying to figure out how to add to the queue so that the items are stored in the queue in order and this is what I have.
On the line that starts if(newItem.compareTo... eclipse is giving me a warning:
Type safety: The method compareTo(Object) belongs to the raw type Comparable. References to generic type Comparable<T> should be parameterized
And I dont know what that means? will my add method work as planned?
Also, my List class has a max size (that is private) and I want it so that if the priority queue tries to add over the max size it will throw an exception but the commented out line just causes an error...any ideas?
Thanks
     public void enqueue(Comparable newItem) throws QueueException
          //if(aList.size() == MAXLIST) throws Exception
          if(aList.size() == 0) aList.add(1, newItem);
          else
               for(int i = 1; i <= aList.size(); i++)
                    if(newItem.compareTo(aList.get(i)) == -1) aList.add(i, newItem);
     }

And I dont know what that means? The warning is referring to generics: http://java.sun.com/docs/books/tutorial/extra/generics/index.html

Here's A Question Using A Priority Queue and a DLL

Ifm trying to make a method that compares two objects that go into a DLL using a priority Queue. SO in other words lets say i have "5" go ino the DLL and then i have "2" that goes in i need to swap the 2 and the 5. And this goes on for any other objects inserted
     private Comparable minPosition() throws EmptyPriorityQueueException {
     if (size() == 0)
     throw new EmptyPriorityQueueException ("No Elements In The Queue");
     else
now this is what i got so far....but i know that i have toi make to vaiables and compare them? little help please?
Thanks

Um, well im using the adapter class, List. so ive gone a bit further, but im not sure on what to do.....
     private Comparable minPosition() throws EmptyPriorityQueueException {
     if (size() == 0)
     throw new EmptyPriorityQueueException ("No Elements In The Queue");
     while (isEmpty()==false)
     r = ((Comparable)elements.first());
     s = ((Comparable)elements.next(elements));
then i can make r=s and make s serach for the next element,?
Can the experienced programmers help me out? Doesn't seem to be a tuff question.

MPLS QoS - SUP720BXL GE Port not supporting Strict Priority & Priority %

Hi Sir,
My customer have few C7609s with SUP720 3BXL and running IOS image s72033-advipservicesk9_wan-mz.122-18.SXF6.bin within the MPLS network.
What I experienced is that I can't configured the built-in GE port of the SUP720 for Strict Priority & Priority Percent QoS.
Is there anyone outside there know what is the equivalent or alternative to above mentioned two QoS features ? This is mainly to priortize the voice traffic.
Thanks in advance.
Ray.

The below has been recommended for a customer using 7600 in the
Core with GiGs as normal core facing links.
The implementation goes as below:
i) Enabling the MLS on the 7600 chassis.
mls qos
ii) Configuring Trust Boundary on all Interfaces.
interface GigabitEthernet1/1
mls qos trust
<--By default the Trust Command trusts the incoming DSCP/TOS.
When the ports are configured with the Trust Boundary as given above,
all incoming packets are mapped into Initial Internal DSCP values.
These values are used purely as a reference MAP for Internal QOS
processing on the 7600.
Internal DSCP Output COS
DSCP 0 7 COS 0
DSCP 8 15 COS 1
DSCP 16 23 COS 2
DSCP 24 31 COS 3
DSCP 32 39 COS 4
DSCP 40 47 COS 5
DSCP 48 55 COS 6
DSCP 56 63 COS 7
This deafault mapping can be modified by modifying the DSCP-COS MAP
within the MLS QOS. The the default mapping are as per standards,
and hence it is not recommended to change the mapping.
iii) Directing Traffic into the appropriate Egress Queue.
Once the incoming traffic is mapped to the Initial Internal DSCP,
and the same gets mapped to the Output COS, these values need to
be directed to the appropriate Queues for the desired QOS behavior
on the MPLS EXP packets.
interface x/x
wrr-queue cos-map
priority-queue cos-map
For Eg:
interface gigabitethernet 1/10
wrr-queue cos-map 2 threshold 2 0
wrr-queue cos-map 3 threshold 2 1 2
wrr-queue cos-map 4 threshold 2 3 4
priority-queue cos-map 1 5 6 7
iv) Defining Queue Bandwidth Limits.
After directing the COS to appropriate queues and then assigning them
to appropriate drop threshold values, it is required to define the
bandwidth allocation per queue. This can be done as below.
!<-- To Set minimum assured bandwidth to COS Queue 1,2 & 3
Use the Bandwdith Percentage command as below.
interface GigabitEthernet 1/1
wrr-queue bandwidth percent !
<--Total of Queue Weights should be =100%
To evenly distribute the available bandwidth during congestion for
all the 4 queues, it is required to set the Queue Scheduling Weights
between all the four Queues. This is done by assigning the queues
weights which are used during WRR scheduling.
!<--Set the Queue-Limit Weights of WRR Scheduling as below
interface GigabitEthernet 1/1
wrr-queue queue-limit
priority-queue queue-limit xx
!<--For Example:
interface GigabitEthernet 1/1
wrr-queue queue-limit 25 20 22
priority-queue queue-limit 33
!<-- The example above does a Queue scheduling for Queue 1 for 25% of BW,
Queue 2 for 20% and Queue 3 for 22 % and Priority Queue has 33 %.
To conclude if you want to use the conventional MQC based toggles,
you will need to use FlexWans with WAN ports or OSM's. Where you can
apply the conventional MQC based toggles.
FOr all the LAN ports in 7600 only hardware queues are supported which
can be controlled using MLS, the difference between SUP and Module based
LAN ports is withing the Scheduling alogirthms supported, the Egress and Ingress
buffers, and the number of queues and drop thresholds available.
For Reference use this link:
http://www.cisco.com/univercd/cc/td/doc/product/core/cis7600/software/122sr/swcg/qos.htm
HTH-Cheers,
Swaroop
PS:
Policy Map Class Command Restrictions
PFC QoS does not support these policy map class commands:
?bandwidth
?priority
?queue-limit
?random-detect
?set qos-group
?service-policy

Java priority queue

Java provides PriorityQueue, and I have gone through its API.
The implementation of PriorityQueue in Java does not provide method for increase or decrease key,
and there must be a reason for it.
But, when i go through books on data strucutre, a lot of them talk about the increase/decrease key function
of the PriorityQueue.
So I am just wondering, why is it that increase/decrease function not provided in PriorityQueue. I cannot come up with a reason for it, but i think there must be. Does anybody have any thought on this. Or is it just
because the designers thought its not needed?
I checked the source for the Priority Queue and the heapify() method was declared private.

lupansansei wrote:
I have used Java's priority queue an I have written my own but I have never come accros the terms "increase or decrease key". Do you mean something like 'upheap' or 'downheap' in relation to a 'heap' implementation meaning move an entry to it correct position if the key changes? If so then one should make the 'key' immutable so that the functions are not needed.
Yes, i mean 'upheap' or 'downheap' by increase or decrease key. Sorry
maybe my choice of words was not correct.
I couldn't get what you mean by 'key' immutable. Can you please explain it. If the key cannot change (i.e. it is immutable) then there is no need to ever change the position of an element.
>
Correct. Since the PriorityQueue does not need to implemented using a 'heap' there is no need for the heapify() method to be exposed. If one implemented using a balanced tree or a skip list the heapify() method would not be applicable.I am using PriorityQueue and i need to update the priority of the elements and i was wondering whether to implement the whole queue
myself or look for a better way of using the PriorityQueue class.
Do you have any suggestions for efficiently updating the priority of element?I have a priority queue implementation where elements know they are in a heap and know where they are in the heap. By doing this I can modify 'keys' and then move a value to it's correct place in the queue in a very short time. The limitations this feature imposes on the elements and the possibility of corrupting the heap means I don't often use this these days. It is far too error prone.
These days in my simulations I normally remove an element from the queue, process the element and then create new elements and insert them back in the queue. This sometimes takes 2 lots of Log(n) operations where my specialized priority queue just takes Log(n) operations. The code is just so much more maintainable and I accept the hit.

Custom order of priority queue

I am a novice in Java. I intend to use a priority queue which holds objects. The objects have a string and two integers. I have to order the priority queue based on one of the integer.
I write syntax according to my understanding please correct me.
PriorityQueue<Object> pr = new PriorityQueue<Object>();
comparable(){
sort(Object.int2)// this is the place where I am confused
}

Here's an example:
public class Caller
    public static void main(String[] args)
        Flight f1 = new Flight( "java", 2, 34 );
        Flight f2 = new Flight( "java", 2, 3 );
        Flight f3 = new Flight( "java", 2, 4 );
        Flight f4 = new Flight( "java", 2, 64 );
        Flight f5 = new Flight( "java", 2, 22 );
        Flight f6 = new Flight( "java", 2, 12 );
        PriorityQueue pq = new PriorityQueue();
        pq.add(f1);
        pq.add(f2);
        pq.add(f3);
        pq.add(f4);
        pq.add(f5);
        pq.add(f6);
        System.out.println(pq.poll());
        System.out.println(pq.poll());
        System.out.println(pq.poll());
        System.out.println(pq.poll());
        System.out.println(pq.poll());
        System.out.println(pq.poll());
public class Flight implements Comparable
    private String airlinename;
    private int flightnumber;
    private int number;
    public int compareTo(Object o)
        Flight f = (Flight) o;
        return number - f.getNumber();
    public String toString()
        return airlinename + " - " + number;
    public Flight(String airname, int num1, int num2)
        airlinename = airname;
        flightnumber = num1;
        number = num2;
    public String getAirlinename()
        return airlinename;
    public void setAirlinename(String airlinename)
        this.airlinename = airlinename;
    public int getFlightnumber()
        return flightnumber;
    public void setFlightnumber(int flightnumber)
        this.flightnumber = flightnumber;
    public int getNumber()
        return number;
    public void setNumber(int number)
        this.number = number;
}Got it?

Queue size

I am supposed to write a program in java where a single queue is shared by multiple java programs.
I tried create a queue in super class and let sub classes access and update it.But when I run the program and check the size of queue in the sub classes it seems like the queue is initializing everytime the superclass is called in each sub class.
The code is as follow:
import java.util.*;
class Que
{public Que() {}
LinkedList<String> queue=new LinkedList<String>();
public void Qadd(String S){queue.addFirst(S);}
public void Qremove(){queue.remove();}
public ListIterator<String> QListiterator() {return queue.listIterator();}
public int Qsize(){int y=queue.size();return y;}}
class Que1 extends Que
{public static void main(String args[]){
Que q=new Que();q.Qadd("A");q.Qadd("B");q.Qadd("C"...
q.Qadd("D");q.Qremove();int size=q.Qsize();
System.out.println("size:"+size);}}
class Que2 extends Que{
public static void main(String args[])
Que q=new Que();q.Qadd("D");
int size=q.Qsize();
System.out.println("size:"+size);}}
Now the size output is 3 and then 0.But I need 3 and then 3.
Can some1 direct me to the right direction in solving my problem??

are you actually running these in separate java instances (you are running the java program multiple times?). if so, you have a lot more work ahead of you. java does not magically share data between different programs. if you need to share data across multiple programs, you need to start looking into remote protocols and distributed processing (or use JMS).
is it possible you just want multiple threads in the same program instead of multiple programs? if so, then things get a lot simpler (not necessarily easy per-se, but much, much simpler).

Priority Queue problem

Hi Everybody.
Can anyone tell me in which order elements of priority queue are sorted.
I have used following code
class Test{
PriorityQueue <strings> pq=new PriorityQueue <Strings>();
pq.add("silpa");
pq.add("swati");
pq.add("roopa");
pq.add("abc");
System.out.println(pq);
System.out.println(pq.poll());
System.out.println(pq.peak());
The output I got is
[abc silpa swathi roopa]
abc
roopa.
Can anybody explain why the collection elements are not sorted ?
I am getting correct output with peek() n poll().According that methods i should get
[abc roopa silpa swathi ]
Explain the reason?

System.out.println(pq);This line prints out the contents of the queue, by implicitly calling pq.toString(), whose behaviour is inherited from AbstractCollection, which therefore has nothing to do with sorting. So you have no valid reason for expecting any particular ordering.

6500 strict priority queue size ???

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