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  • Message Buffers in cloud

    - by kaleidoscope
    Message Buffer is WCF queue in the cloud (although currently it does not provide all features of WCF queue). With on-premise WCF, you can take advantage of MSMQ, so that a message is sent to MSMQ by one endpoint, and another endpoint can get the message in a later time. The message is usually a SOAP message so that you can generate a client proxy and invoke the service operations just as invoking a normal WCF operation. Message Buffer is similar, but it also provides a REST API for you to work with the messages. Use it when you need a reliable WCF service. Message buffers can be consumed by non-azure components, "Message  buffers are accessible to applications using HTTP and do not require the Windows Azure platform AppFabric SDK"              How to: Configure an AppFabric Service Bus Message Buffer :    please find below link for more details: http://msdn.microsoft.com/en-us/library/ee794877.aspx http://msdn.microsoft.com/en-us/library/ee794877.aspx   Chandraprakash, S

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  • The Message Queuing service failed to join the computer's domain 'DOMAIN' Error 0xc00e0025

    - by SimonGoldstone
    Struggling to get MSMQ installed in Domain Integration mode on Windows 2012 (Azure). So far, I've provisioned a brand new Windows Server 2012 (R2) machine on the Azure platform and installed the Active Directory role and promoted the machine to a domain controller. Once the AD was in place, I then added the MSMQ feature, along with the Directory Integration add on. However, it will not install in AD integration mode. It will only work in Workgroup mode. I can verify this by running the following powershell command: New-MSMQQueue -name Queue1 -queuetype Public When I run this command, I get the following error: New-MsmqQueue : A workgroup installation computer does not support the operation. The event viewer reveals to errors in the Application log: 1. The Message Queuing service failed to join the computer's domain 'DOMAIN'. Error 0xc00e0025: 2. Message Queuing was unable to create the msmq (MSMQ Configuration) object in Active Directory Domain Services. Error c00e0025h: I'm struggling here. Any advice?

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  • Windows XP error message: "Windows cannot find 'explorer.exe'"

    - by Meysam
    In Windows XP I can open "My Computer" and see all the hard drives. I can also see the explorer.exe process running among other processes in Task Manager. But after opening "My Computer", when I double click on one of the drives to open it, I get the following error message: Windows cannot find 'explorer.exe'. Make sure you typed the name correctly, and then try again. To search for a file, click the start button, and then click search. Although I could detect and remove several suspicious files using Malwarebytes & Microsoft Security Essentials, the problem still remains. The interesting point is that if I right click on one folder and select Open or Explore from the menu bar, I can open the folder! but if I double click on the folder, it does not open and I get the above error message. How can I fix this problem? Any advice would be appreciated! Update: I formatted the C: drive (NTFS), a deep format, and installed a fresh Windows XP on it. I am not getting this error when I double click on C drive icon anymore. But the same error appears when I double click on other drive names. Maybe I should format them too!

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  • Go - Using a container/heap to implement a priority queue

    - by Seth Hoenig
    In the big picture, I'm trying to implement Dijkstra's algorithm using a priority queue. According to members of golang-nuts, the idiomatic way to do this in Go is to use the heap interface with a custom underlying data structure. So I have created Node.go and PQueue.go like so: //Node.go package pqueue type Node struct { row int col int myVal int sumVal int } func (n *Node) Init(r, c, mv, sv int) { n.row = r n.col = c n.myVal = mv n.sumVal = sv } func (n *Node) Equals(o *Node) bool { return n.row == o.row && n.col == o.col } And PQueue.go: // PQueue.go package pqueue import "container/vector" import "container/heap" type PQueue struct { data vector.Vector size int } func (pq *PQueue) Init() { heap.Init(pq) } func (pq *PQueue) IsEmpty() bool { return pq.size == 0 } func (pq *PQueue) Push(i interface{}) { heap.Push(pq, i) pq.size++ } func (pq *PQueue) Pop() interface{} { pq.size-- return heap.Pop(pq) } func (pq *PQueue) Len() int { return pq.size } func (pq *PQueue) Less(i, j int) bool { I := pq.data.At(i).(Node) J := pq.data.At(j).(Node) return (I.sumVal + I.myVal) < (J.sumVal + J.myVal) } func (pq *PQueue) Swap(i, j int) { temp := pq.data.At(i).(Node) pq.data.Set(i, pq.data.At(j).(Node)) pq.data.Set(j, temp) } And main.go: (the action is in SolveMatrix) // Euler 81 package main import "fmt" import "io/ioutil" import "strings" import "strconv" import "./pqueue" const MATSIZE = 5 const MATNAME = "matrix_small.txt" func main() { var matrix [MATSIZE][MATSIZE]int contents, err := ioutil.ReadFile(MATNAME) if err != nil { panic("FILE IO ERROR!") } inFileStr := string(contents) byrows := strings.Split(inFileStr, "\n", -1) for row := 0; row < MATSIZE; row++ { byrows[row] = (byrows[row])[0 : len(byrows[row])-1] bycols := strings.Split(byrows[row], ",", -1) for col := 0; col < MATSIZE; col++ { matrix[row][col], _ = strconv.Atoi(bycols[col]) } } PrintMatrix(matrix) sum, len := SolveMatrix(matrix) fmt.Printf("len: %d, sum: %d\n", len, sum) } func PrintMatrix(mat [MATSIZE][MATSIZE]int) { for r := 0; r < MATSIZE; r++ { for c := 0; c < MATSIZE; c++ { fmt.Printf("%d ", mat[r][c]) } fmt.Print("\n") } } func SolveMatrix(mat [MATSIZE][MATSIZE]int) (int, int) { var PQ pqueue.PQueue var firstNode pqueue.Node var endNode pqueue.Node msm1 := MATSIZE - 1 firstNode.Init(0, 0, mat[0][0], 0) endNode.Init(msm1, msm1, mat[msm1][msm1], 0) if PQ.IsEmpty() { // make compiler stfu about unused variable fmt.Print("empty") } PQ.Push(firstNode) // problem return 0, 0 } The problem is, upon compiling i get the error message: [~/Code/Euler/81] $ make 6g -o pqueue.6 Node.go PQueue.go 6g main.go main.go:58: implicit assignment of unexported field 'row' of pqueue.Node in function argument make: *** [all] Error 1 And commenting out the line PQ.Push(firstNode) does satisfy the compiler. But I don't understand why I'm getting the error message in the first place. Push doesn't modify the argument in any way.

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  • Implementing Java Priority Queue

    - by Kay
    public class PriorityQueue<T> { private PriorityNode<T> head, tail; private int numItems; public PriorityQueue(){ numItems = 0; head=null; tail=null; } public void add(int priority, T value){ PriorityNode<T> newNode = new PriorityNode<T>(priority,value); if(numItems == 0){ head = newNode; tail = newNode; } else{ head.setNext(newNode); head = newNode; } } } Where PriorityNode is defined as: public class PriorityNode<T> implements Comparable<T> { private T value; private PriorityNode<T> next; private int priority; public PriorityNode(int priority,T newValue){ value = newValue; next = null; priority = 0; } public PriorityNode(T newValue){ value = newValue; next = null; priority = 0; } public void setPriority(int priority){ this.priority = priority; } public int getPriority(){ return this.priority; } public T getValue(){ return value; } public PriorityNode<T> getNext(){ return next; } public void setNext(PriorityNode<T> nextNode){ this.next = nextNode; } public void setValue(T newValue){ value = newValue; } public int compareTo(int pri) { // TODO Auto-generated method stub if(this.priority<pri){ return -1; } else if(this.priority == pri){ return 0; } else{ return 1; } } } I'm having a lot of difficulty using the Comparator here and implementing a priority queue - please point me in the right direction.

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  • Minimal "Task Queue" with stock Linux tools to leverage Multicore CPU

    - by Manuel
    What is the best/easiest way to build a minimal task queue system for Linux using bash and common tools? I have a file with 9'000 lines, each line has a bash command line, the commands are completely independent. command 1 > Logs/1.log command 2 > Logs/2.log command 3 > Logs/3.log ... My box has more than one core and I want to execute X tasks at the same time. I searched the web for a good way to do this. Apparently, a lot of people have this problem but nobody has a good solution so far. It would be nice if the solution had the following features: can interpret more than one command (e.g. command; command) can interpret stream redirects on the lines (e.g. ls > /tmp/ls.txt) only uses common Linux tools Bonus points if it works on other Unix-clones without too exotic requirements.

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  • Task Queue stopped working

    - by pocoa
    I was playing with Goole App Engine Task Queue API to learn how to use it. But I couldn't make it trigger locally. My application is working like a charm when I upload to Google servers. But it doesn't trigger locally. All I see from the admin is the list of the tasks. But when their ETA comes, they just pass it. It's like they runs but they fails and waiting for the retries. But I can't see these events on command line. When I try to click "Run" on admin panel, it runs successfuly and I can see these requests from the command line. I'm using App Engine SDK 1.3.4 on Linux with google-app-engine-django. I'm trying to find the problem from 3 hours now and I couldn't find it. It's also very hard to debug GAE applications. Because debug messages do not appear on console screen. Thanks.

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  • mysterical error

    - by Görkem Buzcu
    i get "customer_service_simulator.exe stopped" error, but i dont know why? this is my c programming project and i have limited time left before deadline. the code is: #include <stdio.h> #include <stdlib.h> #include<time.h> #define FALSE 0 #define TRUE 1 /*A Node declaration to store a value, pointer to the next node and a priority value*/ struct Node { int priority; //arrival time int val; //type int wait_time; int departure_time; struct Node *next; }; Queue Record that will store the following: size: total number of elements stored in the list front: it shows the front node of the queue (front of the queue) rear: it shows the rare node of the queue (rear of the queue) availability: availabity of the teller struct QueueRecord { struct Node *front; struct Node *rear; int size; int availability; }; typedef struct Node *niyazi; typedef struct QueueRecord *Queue; Queue CreateQueue(int); void MakeEmptyQueue(Queue); void enqueue(Queue, int, int); int QueueSize(Queue); int FrontOfQueue(Queue); int RearOfQueue(Queue); niyazi dequeue(Queue); int IsFullQueue(Queue); int IsEmptyQueue(Queue); void DisplayQueue(Queue); void sorteddequeue(Queue); void sortedenqueue(Queue, int, int); void tellerzfunctionz(Queue *, Queue, int, int); int main() { int system_clock=0; Queue waitqueue; int exit, val, priority, customers, tellers, avg_serv_time, sim_time,counter; char command; waitqueue = CreateQueue(0); srand(time(NULL)); fflush(stdin); printf("Enter number of customers, number of tellers, average service time, simulation time\n:"); scanf("%d%c %d%c %d%c %d",&customers, &command,&tellers,&command,&avg_serv_time,&command,&sim_time); fflush(stdin); Queue tellerarray[tellers]; for(counter=0;counter<tellers;counter++){ tellerarray[counter]=CreateQueue(0); //burada teller sayisi kadar queue yaratiyorum } for(counter=0;counter<customers;counter++){ priority=1+(int)rand()%sim_time; //this will generate the arrival time sortedenqueue(waitqueue,1,priority); //here i put the customers in the waiting queue } tellerzfunctionz(tellerarray,waitqueue,tellers,customers); DisplayQueue(waitqueue); DisplayQueue(tellerarray[0]); DisplayQueue(tellerarray[1]); // waitqueue-> printf("\n\n"); system("PAUSE"); return 0; } /*This function initialises the queue*/ Queue CreateQueue(int maxElements) { Queue q; q = (struct QueueRecord *) malloc(sizeof(struct QueueRecord)); if (q == NULL) printf("Out of memory space\n"); else MakeEmptyQueue(q); return q; } /*This function sets the queue size to 0, and creates a dummy element and sets the front and rear point to this dummy element*/ void MakeEmptyQueue(Queue q) { q->size = 0; q->availability=0; q->front = (struct Node *) malloc(sizeof(struct Node)); if (q->front == NULL) printf("Out of memory space\n"); else{ q->front->next = NULL; q->rear = q->front; } } /*Shows if the queue is empty*/ int IsEmptyQueue(Queue q) { return (q->size == 0); } /*Returns the queue size*/ int QueueSize(Queue q) { return (q->size); } /*Shows the queue is full or not*/ int IsFullQueue(Queue q) { return FALSE; } /*Returns the value stored in the front of the queue*/ int FrontOfQueue(Queue q) { if (!IsEmptyQueue(q)) return q->front->next->val; else { printf("The queue is empty\n"); return -1; } } /*Returns the value stored in the rear of the queue*/ int RearOfQueue(Queue q) { if (!IsEmptyQueue(q)) return q->rear->val; else { printf("The queue is empty\n"); return -1; } } /*Displays the content of the queue*/ void DisplayQueue(Queue q) { struct Node *pos; pos=q->front->next; printf("Queue content:\n"); printf("-->Priority Value\n"); while (pos != NULL) { printf("--> %d\t %d\n", pos->priority, pos->val); pos = pos->next; } } void enqueue(Queue q, int element, int priority){ if(IsFullQueue(q)){ printf("Error queue is full"); } else{ q->rear->next=(struct Node *)malloc(sizeof(struct Node)); q->rear=q->rear->next; q->rear->next=NULL; q->rear->val=element; q->rear->priority=priority; q->size++; } } void sortedenqueue(Queue q, int val, int priority) { struct Node *insert,*temp; insert=(struct Node *)malloc(sizeof(struct Node)); insert->val=val; insert->priority=priority; temp=q->front; if(q->size==0){ enqueue(q, val, priority); } else{ while(temp->next!=NULL && temp->next->priority<insert->priority){ temp=temp->next; } //printf("%d",temp->priority); insert->next=temp->next; temp->next=insert; q->size++; if(insert->next==NULL){ q->rear=insert; } } } niyazi dequeue(Queue q) { niyazi del; niyazi deli; del=(niyazi)malloc(sizeof(struct Node)); deli=(niyazi)malloc(sizeof(struct Node)); if(IsEmptyQueue(q)){ printf("Queue is empty!"); return NULL; } else { del=q->front->next; q->front->next=del->next; deli->val=del->val; deli->priority=del->priority; free(del); q->size--; return deli; } } void sorteddequeue(Queue q) { struct Node *temp; struct Node *min; temp=q->front->next; min=q->front; int i; for(i=1;i<q->size;i++) { if(temp->next->priority<min->next->priority) { min=temp; } temp=temp->next; } temp=min->next; min->next=min->next->next; free(temp); if(min->next==NULL){ q->rear=min; } q->size--; } void tellerzfunctionz(Queue *a, Queue b, int c, int d){ int i; int value=0; int priority; niyazi temp; temp=(niyazi)malloc(sizeof(struct Node)); if(c==1){ for(i=0;i<d;i++){ temp=dequeue(b); sortedenqueue((*(a)),temp->val,temp->priority); } } else{ for(i=0;i<d;i++){ while(b->front->next->val==1){ if((*(a+value))->availability==1){ temp=dequeue(b); sortedenqueue((*(a+value)),temp->val,temp->priority); (*(a+value))->rear->val=2; } else{ value++; } } } } } //end of the program

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  • How to display custom processing message in JQuery datatables

    - by Sukhi
    i am using datatables api to display data in my asp.net4.0 application; datatables I have one column [ Delete ] to delete the row data.when i click on this link i send a jquery ajax request to delete the row from database. I want to display a message such as [ Deleting record... ] to the end user until data deleted by server side processing. I put a div on my page and write a message [ Deleting record... ] in a div when i click on delete link i display that message but when delete operation complete it also display a message [ Processing... ](which is inbuilt message of datatables) which looks like odd as two message are displaying. What can i do better to display message to the end user. JSCode $('#tblVideoList .delete').live('click', function (e) { e.preventDefault(); var oTable = $('#tblVideoList').dataTable(); var aPos = oTable.fnGetPosition(this.parentNode); var aData = oTable.fnGetData(aPos[0]); if (confirm('Are you sure want to delete the record.')) { $("#divDelete").show(); var today = new Date(); $.ajax({ type: "GET", cache: false, url: "samplepage.aspx", success: function (msg) { $("#divDelete").hide(); oTable.fnDraw(); } }); } return false; }); Thanks

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  • Changing the BizTalk message output file name

    - by Bill Osuch
    By default, BizTalk creates the filename of the message dropped to a send port as %MessageID%, which is the unique identifier (GUID) of the message. What if you want to create your own filename? To start, create a simple schema, and a basic orchestration that will receive the message and send it right back out, like this: If you deploy this and wire up the ports, you can drop an xml file into your receive port and have it come out at your send port named something like {7A63CAF8-317B-49D5-871F-9FD57910C3A0}.xml. Now, we'll create a new message with a custom filename. First, create a new orchestration variable called NewFileName, of the type System.String. Next, create a second message using the same schema as the message you're receiving in the Receive shape. Now, drag a Construct Message shape to the orchestration. In the shape's properties, set Messages Constructed to be the new message you just created. Double click the Message Assignment shape (inside the Construct shape...) and paste in the following code: Message_2 = Message_1;   NewFileName = Message_1(FILE.ReceivedFileName); NewFileName = NewFileName.Replace(".xml","_"); NewFileName = NewFileName + "output_" + System.DateTime.Now.Year.ToString() + "-" + System.DateTime.Now.Month.ToString();   Message_2(FILE.ReceivedFileName) = NewFileName; Here we make a copy of the received message, get it's original file name (ReceivedFileName), replace its extension with an underscore, and date-stamp it. Finally, add a Send shape and a Port to the surface, and configure them to send the message you just created. You should wind up with an orchestration like this: Deploy it, and create a new send port. It should be just about identical to the first send port, except this time the file name will be "%SourceFileName%.xml" (without the quotes of course). Fire up the application, drop in a test file, and you should now get both the xml file named with a GUID, and a second file named something along the lines of "MySchemaTestFile_output_2011-6.xml".

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  • Job queue manager with RPC interface

    - by admr
    I need a job queue manager that I can control over the Internet. It should be able to execute and stop processes, check on their status (ideally notice and execute some code when a process exits), respond to commands and also be able to report back to a server. Background: I have a GWT application that allows to create jobs to execute on a cloud instance (currently EC2). I want to push a "job packet" (data for a process to operate on etc) to S3, start a Linux EC2 instance (or use one that's already running), and tell a job manager on the instance to execute that job (possibly parallel to other jobs). It should then pull the "job packet" from S3, run a process that operates on that data and report back to the server that is running the server part of my GWT application with some information (e.g. exit code, stdout, stderr). If I have to write e.g. stdour/err to a file from the process and read that file, that's OK too. I would really like the manager to be "close" to the processes it runs, meaning I want to avoid using something like Runtime.exec from the JDK. It seems like I would have to do that if I used Quartz for example. I'm fine with the calls in both directions being asynchronous. I'm fine with any reasonable technology for the calls as long as I can easily build an interface for that in my GWT server side (e.g. HTTP requests to a servlet over SSL would be nice and trivial). The job manager does not need to have a very sophisticated queueing system. Running several processes either sequentially or in parallel should be fine. Determining how much compute time a process received during its lifetime would be nice (AFAIK, this might be challenging). I did not yet find any existing software that does this, including http://java-source.net/open-source/job-schedulers. I suspect I might have to build an RPC interface (with authentication etc, of course) around a job manager; maybe use something like Apache Commons Exec. In that case, I would prefer Java or Python for the job manager part. I would be happy to hear suggestions for either the former or latter scenario!

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  • SQL Error Log Message- 'ACCESS_METHODS_SCAN_RANGE_GENERATOR'

    - by Chirag
    One of our SQL2005 Enterprise Servers running on Win2003 became unresponsive and on reboot I saw these errors logged before it went down. Date 17/09/2009 10:16:22 Log SQL Server (Archive #1 - 17/09/2009 10:17:00) Source spid111 Message Timeout occurred while waiting for latch: class 'ACCESS_METHODS_SCAN_RANGE_GENERATOR', id 000000002A761760, type 4, Task 0x000000000E609EB8 : 14, waittime 600, flags 0x1a, owning task 0x000000000E6129B8. Continuing to wait. Anyone know what this error points or relates to? Many thanks in advance.

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  • Stack Over Flow Message

    - by atul
    I have created an image of my original hard disk, now i have started my pc by image hard disk, windows xp is working fine. but when we are running an other application programm, we are receiving an error message of Stack Over Flow. While my original hard disk is working fine. We don't know that programm is written in which language. I have only exe file of that. Can any one suggest, what may be the reason.

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  • Suppress "running out of disk space" Message (per drive) on Windows Server 2003

    - by Shoeless
    We have a database server with separate drives for OS, various data files and the transaction log. Our transaction log spills over onto other volumes as well- this is expected behavior. The problem is that we are constantly getting popups that our transaction log drive is out of space (and that I can free space by deleting old or unnecessary files). Is there some way to prevent this message from popping up for this particular drive?

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  • Altq limits not being applied to UDP transfers

    - by overkordbaever
    I have a OpenBSD server acting as a router/firewall with yhr packet filter ruleset shown below, a linux server, and a linux client. When transferring files (using netcat) by TCP, the limits are applied (for example the 100mbit limit in the example), though when transferring data by UDP, the limits aren't applied; the file always takes the same amount of time no matter the queue bandwidth limit I set (I can even turn off the queues completely, and will still get the same result). Why aren't the queuing rules applied to UDP packages? The rules used: #queue rules altq on { $int_if, $ext_if } cbq bandwidth 100Mb queue { def, low } queue def bandwidth 0Mb cbq(default) queue low bandwidth 100Mb cbq #Passrules test pass out quick from $int_if to $ext_if queue low pass in quick from $ext_if to $int_if queue low pass out quick from $ext_if to $int_if queue low pass in quick from $int_if to $ext_if queue low I suppose this may be related a question I've previously asked, though since it's more of a separate question, I suppose a separate question should be used for this

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  • Need suggestion for implementing Message alert in Client server application

    - by sandip-mcp
    My requrement is like, i have to display message alert like if you sign in yahoo messanger and once u got any message a alert box will display corner of the page.Like wise when i sign in my website and if anybody send me any message then message will store in database and symultaneously a alert should display in my site. I am using .net framework3.5 using wcf service.So i will appreciate ur suggestion.Thanks in advance

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  • Testing a Non-blocking Queue

    - by jsw
    I've ported the non-blocking queue psuedocode here to C#. The code below is meant as a near verbatim copy of the paper. What approach would you take to test the implementation? Note: I'm running in VS2010 so I don't have CHESS support yet. using System.Threading; #pragma warning disable 0420 namespace ConcurrentCollections { class QueueNodePointer<T> { internal QueueNode<T> ptr; internal QueueNodePointer() : this(null) { } internal QueueNodePointer(QueueNode<T> ptr) { this.ptr = ptr; } } class QueueNode<T> { internal T value; internal QueueNodePointer<T> next; internal QueueNode() : this(default(T)) { } internal QueueNode(T value) { this.value = value; this.next = new QueueNodePointer<T>(); } } public class ConcurrentQueue<T> { private volatile int count = 0; private QueueNodePointer<T> qhead = new QueueNodePointer<T>(); private QueueNodePointer<T> qtail = new QueueNodePointer<T>(); public ConcurrentQueue() { var node = new QueueNode<T>(); node.next.ptr = null; this.qhead.ptr = this.qtail.ptr = node; } public int Count { get { return this.count; } } public void Enqueue(T value) { var node = new QueueNode<T>(value); node.next.ptr = null; QueueNodePointer<T> tail; QueueNodePointer<T> next; while (true) { tail = this.qtail; next = tail.ptr.next; if (tail == this.qtail) { if (next.ptr == null) { var newtail = new QueueNodePointer<T>(node); if (Interlocked.CompareExchange(ref tail.ptr.next, newtail, next) == next) { Interlocked.Increment(ref this.count); break; } else { Interlocked.CompareExchange(ref this.qtail, new QueueNodePointer<T>(next.ptr), tail); } } } } Interlocked.CompareExchange(ref this.qtail, new QueueNodePointer<T>(node), tail); } public T Dequeue() { T value; while (true) { var head = this.qhead; var tail = this.qtail; var next = head.ptr.next; if (head == this.qhead) { if (head.ptr == tail.ptr) { if (next.ptr == null) { return default(T); } Interlocked.CompareExchange(ref this.qtail, new QueueNodePointer<T>(next.ptr), tail); } else { value = next.ptr.value; var newhead = new QueueNodePointer<T>(next.ptr); if (Interlocked.CompareExchange(ref this.qhead, newhead, head) == head) { Interlocked.Decrement(ref this.count); break; } } } } return value; } } } #pragma warning restore 0420

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  • Lockless queue implementation ends up having a loop under stress

    - by Fozi
    I have lockless queues written in C in form of a linked list that contains requests from several threads posted to and handled in a single thread. After a few hours of stress I end up having the last request's next pointer pointing to itself, which creates an endless loop and locks up the handling thread. The application runs (and fails) on both Linux and Windows. I'm debugging on Windows, where my COMPARE_EXCHANGE_PTR maps to InterlockedCompareExchangePointer. This is the code that pushes a request to the head of the list, and is called from several threads: void push_request(struct request * volatile * root, struct request * request) { assert(request); do { request->next = *root; } while(COMPARE_EXCHANGE_PTR(root, request, request->next) != request->next); } This is the code that gets a request from the end of the list, and is only called by a single thread that is handling them: struct request * pop_request(struct request * volatile * root) { struct request * volatile * p; struct request * request; do { p = root; while(*p && (*p)->next) p = &(*p)->next; // <- loops here request = *p; } while(COMPARE_EXCHANGE_PTR(p, NULL, request) != request); assert(request->next == NULL); return request; } Note that I'm not using a tail pointer because I wanted to avoid the complication of having to deal with the tail pointer in push_request. However I suspect that the problem might be in the way I find the end of the list. There are several places that push a request into the queue, but they all look generaly like this: // device->requests is defined as struct request * volatile requests; struct request * request = malloc(sizeof(struct request)); if(request) { // fill out request fields push_request(&device->requests, request); sem_post(device->request_sem); } The code that handles the request is doing more than that, but in essence does this in a loop: if(sem_wait_timeout(device->request_sem, timeout) == sem_success) { struct request * request = pop_request(&device->requests); // handle request free(request); } I also just added a function that is checking the list for duplicates before and after each operation, but I'm afraid that this check will change the timing so that I will never encounter the point where it fails. (I'm waiting for it to break as I'm writing this.) When I break the hanging program the handler thread loops in pop_request at the marked position. I have a valid list of one or more requests and the last one's next pointer points to itself. The request queues are usually short, I've never seen more then 10, and only 1 and 3 the two times I could take a look at this failure in the debugger. I thought this through as much as I could and I came to the conclusion that I should never be able to end up with a loop in my list unless I push the same request twice. I'm quite sure that this never happens. I'm also fairly sure (although not completely) that it's not the ABA problem. I know that I might pop more than one request at the same time, but I believe this is irrelevant here, and I've never seen it happening. (I'll fix this as well) I thought long and hard about how I can break my function, but I don't see a way to end up with a loop. So the question is: Can someone see a way how this can break? Can someone prove that this can not? Eventually I will solve this (maybe by using a tail pointer or some other solution - locking would be a problem because the threads that post should not be locked, I do have a RW lock at hand though) but I would like to make sure that changing the list actually solves my problem (as opposed to makes it just less likely because of different timing).

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  • Can't insert cells in Excel 2010 - "operation not allowed" error message

    - by Force Flow
    I was working on a spreadsheet in Excel 2010, and all of a sudden when I attempted to insert a new row of cells, I saw that the insert and delete options were grayed out. I attempted to copy a different row and insert it as a new row, but I got the error message: "This operation is not allowed. The operation is attempting to shift cells in a table on your worksheet." I have not merged or hidden any cells/rows/columns. There are no formulas. There is no data verification. I tried closing and re-opening the spreadsheet. Searching for answers brings up nothing useful.

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  • Cash Application Work Queue in Oracle Receivables Release 12.1.1

    - by Robert Story
    Upcoming WebcastTitle: Cash Application Work Queue in Oracle Receivables Release 12.1.1Date: March 24, 2010Time: 10:00 am EDT, 7:00 am PDT, 14:00 GMT Product Family: E-Business Suite Receivables 12.1.1 Receipts Summary Understand the setups and processes for the Cash Application Work Queue in Release 12.1.1 and learn how to diagnose basic functional issues. This one-hour session is recommended for technical and functional users. We will be covering topics related to processing receipts efficiently, managing the work load of cash application owners and diagnosing issues. Topics will include: Description of Cash Application Work Queue Setup and Work Queue Process Dependencies and Interactions Basic Troubleshooting Steps A short, live demonstration (only if applicable) and question and answer period will be included. Click here to register for this session....... ....... ....... ....... ....... ....... .......The above webcast is a service of the E-Business Suite Communities in My Oracle Support.For more information on other webcasts, please reference the Oracle Advisor Webcast Schedule.Click here to visit the E-Business Communities in My Oracle Support Note that all links require access to My Oracle Support.

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  • how to make a queue in php with mysql

    - by robert
    hy, in my script i run a exec() function to make a movie file with ffmpeg. the problem is ffmpeg can run only 1 time on the server, if 2 people are online on server and first one already run ffmpeg i want the second to wait until the first end the process how to code this? thank you

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  • Any other kinds of "Task Queue" APIs ?

    - by sork
    I'm curious if it's common practice outside of the GAE platform to be able to defer tasks to background workers via webhooks. I find it particularly useful to speed up the front-end of webapps, by delegating any long process to background tasks. I'd like to hear about open source software allowing to implement a TaskQueue-like API, with webhooks preferably, if anyone has some experience in this area. Thanks!

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  • Which persistent & lightweight queue messaging for cross domain (> 2) data exchange with rails integ

    - by Erwan
    Hi all, I'm looking for the right messaging system for my needs. Can you help me ? For now, there won't be a huge amount of data to process, but I don't want to be limited later ... The machines are not just web servers, so the messaging tool should be lightweight, even if processing is not very speed. When some data change on a server, all servers should have the information and process it locally. (should I create one channel per server on each of them ?) The frontend is written on Rails, so it is important, in order to simplify the development, that there is a gem / plugin to manage communications and data sent. At this time : RabbitMQ + workling seems to fit my needs. Could this be a right choice ? ActiveMQ make me afraid, because of Java (I really don't know very well Java, but it seems to me to be big CPU consumer) Others don't seem to be as mature as them. There might be lot of development using this kind of technology, so I can't go to the wrong way ! Thank you for help.

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