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  • sql server deadlock issue on a single table..................

    - by devendra
    I have one table let's say "xxx "in sql server 2000 . One .exe is inserting data into that table "xxx" through sql job. But once data is inserted , one stored procedure is reading the data from that "xxx table "and inserting/updating into other two tables and updating back the status into the same "xxx" table. Now, client says that multiple deadlocks are occuring on that "xxx" table . please kindly anyone sdvice me the resolution steps to be taken to resolve this deadlock issue and how to identify it step by step............. Thanks in advance..... XXX

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  • Deadlock between select and truncate (postgresql)

    - by valodzka
    Table output_values_center1 (and some other) inherits output_values. Periodically I truncate table output_values_center1 and load new data (in one transaction). In that time user can request some data and he got error message. Why it ever happens (select query requests only one record) and how to avoid such problem: 2010-05-19 14:43:17 UTC ERROR: deadlock detected 2010-05-19 14:43:17 UTC DETAIL: Process 25972 waits for AccessShareLock on relation 2495092 of database 16385; blocked by process 26102. Process 26102 waits for AccessExclusiveLock on relation 2494865 of database 16385; blocked by process 25972. Process 25972: SELECT * FROM "output_values" WHERE ("output_values".id = 122312) LIMIT 1 Process 26102: TRUNCATE TABLE "output_values_center1"

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  • why single SQL delete statement will cause deadlock?

    - by George2
    Hello everyone, I am using SQL Server 2008 Enterprise. I am wondering why even a single delete statement of this store procedure will cause deadlock if executed by multiple threads at the same time? For the delete statement, Param1 is a column of table FooTable, Param1 is a foreign key of another table (refers to another primary key clustered index column of the other table). There is no index on Param1 itself for table FooTable. FooTable has another column which is used as clustered primary key, but not Param1 column. create PROCEDURE [dbo].[FooProc] ( @Param1 int ,@Param2 int ,@Param3 int ) AS DELETE FooTable WHERE Param1 = @Param1 INSERT INTO FooTable ( Param1 ,Param2 ,Param3 ) VALUES ( @Param1 ,@Param2 ,@Param3 ) DECLARE @ID bigint SET @ID = ISNULL(@@Identity,-1) IF @ID > 0 BEGIN SELECT IdentityStr FROM FooTable WHERE ID = @ID END thanks in advance, George

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  • SendMessage to window created by AllocateHWND cause deadlock

    - by user2704265
    In my Delphi project, I derive a thread class TMyThread, and follow the advice from forums to use AllocateHWnd to create a window handle. In TMyThread object, I call SendMessage to send message to the window handle. When the messages sent are in small volume, then the application works well. However, when the messages are in large volume, the application will deadlock and lose responses. I think may be the message queue is full as in LogWndProc, there are only codes to process the message, but no codes to remove the messages from the queue, that may cause all the processed messages still exist in the queue and the queue becomes full. Is that correct? The codes are attached below: var hLogWnd: HWND = 0; procedure TForm1.FormCreate(Sender: TObject); begin hLogWnd := AllocateHWnd(LogWndProc); end; procedure TForm1.FormDestroy(Sender: TObject); begin if hLogWnd <> 0 then DeallocateHWnd(hLogWnd); end; procedure TForm1.LogWndProc(var Message: TMessage); var S: PString; begin if Message.Msg = WM_UPDATEDATA then begin S := PString(msg.LParam); try List1.Items.Add(S^); finally Dispose(S); end; end else Message.Result := DefWindowProc(hLogWnd, Message.Msg, Message.WParam, Message.LParam); end; procedure TMyThread.SendLog(I: Integer); var Log: PString; begin New(Log); Log^ := 'Log: current stag is ' + IntToStr(I); SendMessage(hLogWnd, WM_UPDATEDATA, 0, LPARAM(Log)); Dispose(Log); end;

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  • how avoids deadlock condition

    - by rima
    Hi I try to write a program like a compiler.In this case I must simulate these codes of SQLPL(This one can be just for example).for example in command prompt i wana do these: c:\> sqlplus .... Enter User-Name:(here we must enter username) xxxx Enter password:(same up)yyyyy ... sql>(now i want to send my sql command to shell)prompt "rima"; "rima" [<-output] sql> prompt "xxxx" sql> exit very simple. I try to use this code: ProcessStartInfo psi = new ProcessStartInfo( @"sqlplus"); psi.UseShellExecute = false; psi.CreateNoWindow = true; psi.RedirectStandardInput = true; psi.RedirectStandardOutput = true; //psi.RedirectStandardError = true; Process process = new Process(); process.StartInfo = psi; bool started = process.Start(); if (started) { process.StandardInput.WriteLine("user/password"); process.StandardInput.Flush(); string ret = process.StandardOutput.ReadLine(); // <-- stalls here System.Console.WriteLine("sqlplus says :" + ret + "\"."); } i find out it form here but as if u read this code has problem!DEADLOCK Condition problem! this is my second time i ask my question,every time my knowledge growing,but i cant get how I can solve my problem at last!!! So I kindly kiss your hand,please help me,these process is not clear for me.any one can give me a code that handle my problem?Already i look at all codes,also I try to use ProcessRunner that in my last post some one offer me,but I cant use it also,i receive an error. I hope by first example u find out what i want,and solve the second code problem... thanks I use C# for implemantation

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  • Resolve php "deadlock"

    - by Matt
    Hey all, I'm currently running into a situation that I guess would be called deadlock. I'm implementing a message service that calls various object methods.. it's quite similar to observer pattern.. Here's whats going on: Dispatcher.php Dispatcher.php <? class Dispatcher { ... public function message($name, $method) { // Find the object based on the name $object = $this->findObjectByName($name); // Slight psuedocode.. for ease of example if($this->not_initialized($object)) $object = new $object(); // This is where it locks up. } return $object->$method(); ... } class A { function __construct() { $Dispatcher->message("B", "getName"); } public function getName() { return "Class A"; } } class B { function __construct() { // Assume $Dispatcher is the classes $Dispatcher->message("A", "getName"); } public function getName() { return "Class B"; } } ?> It locks up when neither object is initialized. It just goes back and forth from message each other and no one can be initialized. Any help would be immensely helpful.. Thanks! Matt Mueller

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  • java - question about thread abortion and deadlock - volatile keyword

    - by Tiyoal
    Hello all, I am having some troubles to understand how I have to stop a running thread. I'll try to explain it by example. Assume the following class: public class MyThread extends Thread { protected volatile boolean running = true; public void run() { while (running) { synchronized (someObject) { while (someObject.someCondition() == false && running) { try { someObject.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } // do something useful with someObject } } } public void halt() { running = false; interrupt(); } } Assume the thread is running and the following statement is evaluated to true: while (someObject.someCondition() == false && running) Then, another thread calls MyThread.halt(). Eventhough this function sets 'running' to false (which is a volatile boolean) and interrupts the thread, the following statement is still executed: someObject.wait(); We have a deadlock. The thread will never be halted. Then I came up with this, but I am not sure if it is correct: public class MyThread extends Thread { protected volatile boolean running = true; public void run() { while (running) { synchronized (someObject) { while (someObject.someCondition() == false && running) { try { someObject.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } // do something useful with someObject } } } public void halt() { running = false; synchronized(someObject) { interrupt(); } } } Is this correct? Is this the most common way to do this? This seems like an obvious question, but I fail to come up with a solution. Thanks a lot for your help.

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  • Deadlock problem

    - by DoomStone
    Hello i'm having a deadlock problem with the following code. It happens when i call the function getMap(). But i can't reealy see what can cause this. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Drawing; using System.Drawing.Imaging; using System.Threading; using AForge; using AForge.Imaging; using AForge.Imaging.Filters; using AForge.Imaging.Textures; using AForge.Math.Geometry; namespace CDIO.Library { public class Polygon { List<IntPoint> hull; public Polygon(List<IntPoint> hull) { this.hull = hull; } public bool inPoly(int x, int y) { int i, j = hull.Count - 1; bool oddNodes = false; for (i = 0; i < hull.Count; i++) { if (hull[i].Y < y && hull[j].Y >= y || hull[j].Y < y && hull[i].Y >= y) { try { if (hull[i].X + (y - hull[i].X) / (hull[j].X - hull[i].X) * (hull[j].X - hull[i].X) < x) { oddNodes = !oddNodes; } } catch (DivideByZeroException e) { if (0 < x) { oddNodes = !oddNodes; } } } j = i; } return oddNodes; } public Rectangle getRectangle() { int x = -1, y = -1, width = -1, height = -1; foreach (IntPoint item in hull) { if (item.X < x || x == -1) x = item.X; if (item.Y < y || y == -1) y = item.Y; if (item.X > width || width == -1) width = item.X; if (item.Y > height || height == -1) height = item.Y; } return new Rectangle(x, y, width-x, height-y); } public Point[] getMap() { List<Point> points = new List<Point>(); lock (hull) { Rectangle rect = getRectangle(); for (int x = rect.X; x <= rect.X + rect.Width; x++) { for (int y = rect.Y; y <= rect.Y + rect.Height; y++) { if (inPoly(x, y)) points.Add(new Point(x, y)); } } } return points.ToArray(); } public float calculateArea() { List<IntPoint> list = new List<IntPoint>(); list.AddRange(hull); list.Add(hull[0]); float area = 0.0f; for (int i = 0; i < hull.Count; i++) { area += list[i].X * list[i + 1].Y - list[i].Y * list[i + 1].X; } area = area / 2; if (area < 0) area = area * -1; return area; } } }

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  • Java deadlock problem....

    - by markovuksanovic
    I am using java sockets for communication. On the client side I have some processing and at this point I send an object to the cient. The code is as follows: while (true) { try { Socket server = new Socket("localhost", 3000); OutputStream os = server.getOutputStream(); InputStream is = server.getInputStream(); CommMessage commMessage = new CommMessageImpl(); ByteArrayOutputStream bos = new ByteArrayOutputStream(); ObjectOutputStream oos = new ObjectOutputStream(bos); oos.writeObject(commMessage); os.write(bos.toByteArray()); os.flush(); byte[] buff = new byte[512]; int bytesRead = 0; ByteArrayOutputStream receivedObject = new ByteArrayOutputStream(); while ((bytesRead = is.read(buff)) > -1) { receivedObject.write(buff, 0, bytesRead); System.out.println(receivedObject); } os.close(); Thread.sleep(10000); } catch (IOException e) { } catch (InterruptedException e) { } } Next on the server side I have the following code to read the object and write the response (Which is just an echo message) public void startServer() { Socket client = null; try { server = new ServerSocket(3000); logger.log(Level.INFO, "Waiting for connections."); client = server.accept(); logger.log(Level.INFO, "Accepted a connection from: " + client.getInetAddress()); os = new ObjectOutputStream(client.getOutputStream()); is = new ObjectInputStream(client.getInputStream()); // Read contents of the stream and store it into a byte array. byte[] buff = new byte[512]; int bytesRead = 0; ByteArrayOutputStream receivedObject = new ByteArrayOutputStream(); while ((bytesRead = is.read(buff)) > -1) { receivedObject.write(buff, 0, bytesRead); } // Check if received stream is CommMessage or not contents. CommMessage commMessage = getCommMessage(receivedObject); if (commMessage != null) { commMessage.setSessionState(this.sessionManager.getState().getState()); ByteArrayOutputStream bos = new ByteArrayOutputStream(); ObjectOutputStream oos = new ObjectOutputStream(bos); oos.writeObject(commMessage); os.write(bos.toByteArray()); System.out.println(commMessage.getCommMessageType()); } else { processData(receivedObject, this.sessionManager); } os.flush(); } catch (IOException e) { } finally { try { is.close(); os.close(); client.close(); server.close(); } catch (IOException e) { } } } The above code works ok if I do not try to read data on the client side (If i exclude the code related to reading). But if I have that code, for some reason, I get some kind of deadlock when accessing input streams. Any ideas what I might have done wrong? Thanks in advance.

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  • Deadlock Analysis in NetBeans 8

    - by Geertjan
    Lock contention profiling is very important in multi-core environments. Lock contention occurs when a thread tries to acquire a lock while another thread is holding it, forcing it to wait. Lock contentions result in deadlocks. Multi-core environments have even more threads to deal with, causing an increased likelihood of lock contentions. In NetBeans 8, the NetBeans Profiler has new support for displaying detailed information about lock contention, i.e., the relationship between the threads that are locked. After all, whenever there's a deadlock, in any aspect of interaction, e.g., a political deadlock, it helps to be able to point to the responsible party or, at least, the order in which events happened resulting in the deadlock. As an example, let's take the handy Deadlock sample code from the Java Tutorial and look at the tools in NetBeans IDE for identifying and analyzing the code. The description of the deadlock is nice: Alphonse and Gaston are friends, and great believers in courtesy. A strict rule of courtesy is that when you bow to a friend, you must remain bowed until your friend has a chance to return the bow. Unfortunately, this rule does not account for the possibility that two friends might bow to each other at the same time. To help identify who bowed first or, at least, the order in which bowing took place, right-click the file and choose "Profile File". In the Profile Task Manager, make the choices below: When you have clicked Run, the Threads window shows the two threads are blocked, i.e., the red "Monitor" lines tell you that the related threads are blocked while trying to enter a synchronized method or block: But which thread is holding the lock? Which one is blocked by the other? The above visualization does not answer these questions. New in NetBeans 8 is that you can analyze the deadlock in the new Lock Contention window to determine which of the threads is responsible for the lock: Here is the code that simulates the lock, very slightly tweaked at the end, where I use "setName" on the threads, so that it's even easier to analyze the threads in the relevant NetBeans tools. Also, I converted the anonymous inner Runnables to lambda expressions. package org.demo; public class Deadlock { static class Friend { private final String name; public Friend(String name) { this.name = name; } public String getName() { return this.name; } public synchronized void bow(Friend bower) { System.out.format("%s: %s" + " has bowed to me!%n", this.name, bower.getName()); bower.bowBack(this); } public synchronized void bowBack(Friend bower) { System.out.format("%s: %s" + " has bowed back to me!%n", this.name, bower.getName()); } } public static void main(String[] args) { final Friend alphonse = new Friend("Alphonse"); final Friend gaston = new Friend("Gaston"); Thread t1 = new Thread(() -> { alphonse.bow(gaston); }); t1.setName("Alphonse bows to Gaston"); t1.start(); Thread t2 = new Thread(() -> { gaston.bow(alphonse); }); t2.setName("Gaston bows to Alphonse"); t2.start(); } } In the above code, it's extremely likely that both threads will block when they attempt to invoke bowBack. Neither block will ever end, because each thread is waiting for the other to exit bow. Note: As you can see, it really helps to use "Thread.setName", everywhere, wherever you're creating a Thread in your code, since the tools in the IDE become a lot more meaningful when you've defined the name of the thread because otherwise the Profiler will be forced to use thread names like "thread-5" and "thread-6", i.e., based on the order of the threads, which is kind of meaningless. (Normally, except in a simple demo scenario like the above, you're not starting the threads in the same class, so you have no idea at all what "thread-5" and "thread-6" mean because you don't know the order in which the threads were started.) Slightly more compact: Thread t1 = new Thread(() -> { alphonse.bow(gaston); },"Alphonse bows to Gaston"); t1.start(); Thread t2 = new Thread(() -> { gaston.bow(alphonse); },"Gaston bows to Alphonse"); t2.start();

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  • Troubleshooting a COM+ application deadlock

    - by Chris Karcher
    I'm trying to troubleshoot a COM+ application that deadlocks intermittently. The last time it locked up, I was able to take a usermode dump of the dllhost process and analyze it using WinDbg. After inspecting all the threads and locks, it all boils down to a critical section owned by this thread: ChildEBP RetAddr Args to Child 0deefd00 7c822114 77e6bb08 000004d4 00000000 ntdll!KiFastSystemCallRet 0deefd04 77e6bb08 000004d4 00000000 0deefd48 ntdll!ZwWaitForSingleObject+0xc 0deefd74 77e6ba72 000004d4 00002710 00000000 kernel32!WaitForSingleObjectEx+0xac 0deefd88 75bb22b9 000004d4 00002710 00000000 kernel32!WaitForSingleObject+0x12 0deeffb8 77e660b9 000a5cc0 00000000 00000000 comsvcs!PingThread+0xf6 0deeffec 00000000 75bb21f1 000a5cc0 00000000 kernel32!BaseThreadStart+0x34 The object it's waiting on is an event: 0:016> !handle 4d4 f Handle 000004d4 Type Event Attributes 0 GrantedAccess 0x1f0003: Delete,ReadControl,WriteDac,WriteOwner,Synch QueryState,ModifyState HandleCount 2 PointerCount 4 Name <none> No object specific information available As far as I can tell, the event never gets signaled, causing the thread to hang and hold up several other threads in the process. Does anyone have any suggestions for next steps in figuring out what's going on? Now, seeing as the method is called PingThread, is it possible that it's trying to ping another thread in the process that's already deadlocked? UPDATE This actually turned out to be a bug in the Oracle 10.2.0.1 client. Although, I'm still interested in ideas on how I could have figured this out without finding the bug in Oracle's bug database.

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  • A deadlock was detected while trying to lock variables in SSIS

    Error: 0xC001405C at SQL Log Status: A deadlock was detected while trying to lock variables "User::RowCount" for read/write access. A lock cannot be acquired after 16 attempts. The locks timed out. Have you ever considered variable locking when building your SSIS packages? I expect many people haven’t just because most of the time you never see an error like the one above. I’ll try and explain a few key concepts about variable locking and hopefully you never will see that error. First of all, what is all this variable locking all about? Put simply SSIS variables have to be locked before they can be accessed, and then of course unlocked once you have finished with them. This is baked into SSIS, presumably to reduce the risk of race conditions, but with that comes some additional overhead in that you need to be careful to avoid lock conflicts in some scenarios. The most obvious place you will come across any hint of locking (no pun intended) is the Script Task or Script Component with their ReadOnlyVariables and ReadWriteVariables properties. These two properties allow you to enter lists of variables to be used within the task, or to put it another way, these lists of variables to be locked, so that they are available within the task. During the task pre-execute phase the variables and locked, you then use them during the execute phase when you code is run, and then unlocked for you during the post-execute phase. So by entering the variable names in one of the two list, the locking is taken care of for you, and you just read and write to the Dts.Variables collection that is exposed in the task for the purpose. As you can see in the image above, the variable PackageInt is specified, which means when I write the code inside that task I don’t have to worry about locking at all, as shown below. public void Main() { // Set the variable value to something new Dts.Variables["PackageInt"].Value = 199; // Raise an event so we can play in the event handler bool fireAgain = true; Dts.Events.FireInformation(0, "Script Task Code", "This is the script task raising an event.", null, 0, ref fireAgain); Dts.TaskResult = (int)ScriptResults.Success; } As you can see as well as accessing the variable, hassle free, I also raise an event. Now consider a scenario where I have an event hander as well as shown below. Now what if my event handler uses tries to use the same variable as well? Well obviously for the point of this post, it fails with the error quoted previously. The reason why is clearly illustrated if you consider the following sequence of events. Package execution starts Script Task in Control Flow starts Script Task in Control Flow locks the PackageInt variable as specified in the ReadWriteVariables property Script Task in Control Flow executes script, and the On Information event is raised The On Information event handler starts Script Task in On Information event handler starts Script Task in On Information event handler attempts to lock the PackageInt variable (for either read or write it doesn’t matter), but will fail because the variable is already locked. The problem is caused by the event handler task trying to use a variable that is already locked by the task in Control Flow. Events are always raised synchronously, therefore the task in Control Flow that is raising the event will not regain control until the event handler has completed, so we really do have un-resolvable locking conflict, better known as a deadlock. In this scenario we can easily resolve the problem by managing the variable locking explicitly in code, so no need to specify anything for the ReadOnlyVariables and ReadWriteVariables properties. public void Main() { // Set the variable value to something new, with explicit lock control Variables lockedVariables = null; Dts.VariableDispenser.LockOneForWrite("PackageInt", ref lockedVariables); lockedVariables["PackageInt"].Value = 199; lockedVariables.Unlock(); // Raise an event so we can play in the event handler bool fireAgain = true; Dts.Events.FireInformation(0, "Script Task Code", "This is the script task raising an event.", null, 0, ref fireAgain); Dts.TaskResult = (int)ScriptResults.Success; } Now the package will execute successfully because the variable lock has already been released by the time the event is raised, so no conflict occurs. For those of you with a SQL Engine background this should all sound strangely familiar, and boils down to getting in and out as fast as you can to reduce the risk of lock contention, be that SQL pages or SSIS variables. Unfortunately we cannot always manage the locking ourselves. The Execute SQL Task is very often used in conjunction with variables, either to pass in parameter values or get results out. Either way the task will manage the locking for you, and will fail when it cannot lock the variables it requires. The scenario outlined above is clear cut deadlock scenario, both parties are waiting on each other, so it is un-resolvable. The mechanism used within SSIS isn’t actually that clever, and whilst the message says it is a deadlock, it really just means it tried a few times, and then gave up. The last part of the error message is actually the most accurate in terms of the failure, A lock cannot be acquired after 16 attempts. The locks timed out.  Now this may come across as a recommendation to always manage locking manually in the Script Task or Script Component yourself, but I think that would be an overreaction. It is more of a reminder to be aware that in high concurrency scenarios, especially when sharing variables across multiple objects, locking is important design consideration. Update – Make sure you don’t try and use explicit locking as well as leaving the variable names in the ReadOnlyVariables and ReadWriteVariables lock lists otherwise you’ll get the deadlock error, you cannot lock a variable twice!

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  • How should I debug a vb.net website in iis6 that is throwing 'Deadlock detected' errors and becomes

    - by jskunkle
    A few times a day, our vb.net (IIS 6.0) website is randomly throwing the following error and becomes completely unavailable for 5-15 minutes at a time while the application is recycled: ISAPI 'c:\windows\microsoft.net\framework\v2.0.50727\aspnet_isapi.dll' reported itself as unhealthy for the following reason: 'Deadlock detected'. The website ran for months on the exact same server in beta without problem - but the problem started over the weekend when we made the site live. The live site is under some load but less than many of our other production websites. How should I attack this problem? I've looked into orphaning the worker process and creating a dump file - but I'm not sure how to analyze that. Any advice or information is appreciated. Thanks, Shane

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  • SQL 2005 Transaction Rollback Hung–unresolved deadlock

    - by steveh99999
    Encountered an interesting issue recently with a SQL 2005 sp3 Enterprise Edition system. Every weekend, a full database reindex was being run on this system – normally this took around one and a half hours. Then, one weekend, the job ran for over 17 hours  - and had yet to complete... At this point, DBA cancelled the job. Job status is now cancelled – issue over…   However, cancelling the job had not killed the reindex transaction – DBCC OPENTRAN was still showing the transaction being open. The oldest open transaction in the database was now over 17 hours old.  Consequently, transaction log % used growing dramatically and locks still being held in the database... Further attempts to kill the transaction did nothing. ie we had a transaction which could not be killed. In sysprocesses, it was apparent the SPID was in rollback status, but the spid was not accumulating CPU or IO. Was the SPID stuck ? On examination of the SQL errorlog – shortly after the reindex had started, a whole bunch of deadlock output had been produced by trace flag 1222. Then this :- spid5s      ***Stack Dump being sent to   xxxxxxx\SQLDump0042.txt spid5s      * ******************************************************************************* spid5s      * spid5s      * BEGIN STACK DUMP: spid5s      *   12/05/10 01:04:47 spid 5 spid5s      * spid5s      * Unresolved deadlock spid5s      * spid5s      *   spid5s      * ******************************************************************************* spid5s      * ------------------------------------------------------------------------------- spid5s      * Short Stack Dump spid5s      Stack Signature for the dump is 0x000001D7 spid5s      External dump process return code 0x20000001. Unresolved deadlock – don’t think I’ve ever seen one of these before…. A quick call to Microsoft support confirmed the following bug had been hit :- http://support.microsoft.com/kb/961479 So, only option to get rid of the hung spid – to restart SQL Server… Fortunately SQL Server restarted without any issues. I was pleasantly surprised to see that recovery on this particular database was fast. However, restarting SQL Server to fix an issue is not something I would normally rush to do... Short term fix – the reindex was changed to use MAXDOP of 1. Longer term fix will be to apply the correct CU, or wait for SQL 2005 sp 4 ?? This should be released any day soon I hope..

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  • Why are these two sql statements deadlocking? (Deadlock graph + details included).

    - by Pure.Krome
    Hi folks, I've got the following deadlock graph that describes two sql statements that are deadlocking each other. I'm just not sure how to analyse this and then fix up my sql code to prevent this from happening. Main deadlock graph Click here for a bigger image. Left side, details Click here for a bigger image. Right side, details Click here for a bigger image. What is the code doing? I'm reading in a number of files (eg. lets say 3, for this example). Each file contains different data BUT the same type of data. I then insert data into LogEntries table and then (if required) I insert or delete something from the ConnectedClients table. Here's my sql code. using (TransactionScope transactionScope = new TransactionScope()) { _logEntryRepository.InsertOrUpdate(logEntry); // Now, if this log entry was a NewConnection or an LostConnection, then we need to make sure we update the ConnectedClients. if (logEntry.EventType == EventType.NewConnection) { _connectedClientRepository.Insert(new ConnectedClient { LogEntryId = logEntry.LogEntryId }); } // A (PB) BanKick does _NOT_ register a lost connection .. so we need to make sure we handle those scenario's as a LostConnection. if (logEntry.EventType == EventType.LostConnection || logEntry.EventType == EventType.BanKick) { _connectedClientRepository.Delete(logEntry.ClientName, logEntry.ClientIpAndPort); } _unitOfWork.Commit(); transactionScope.Complete(); } Now each file has it's own UnitOfWork instance (which means it has it's own database connection, transaction and repository context). So i'm assuming this means there's 3 different connections to the db all happening at the same time. Finally, this is using Entity Framework as the repository, but please don't let that stop you from having a think about this problem. Using a profiling tool, the Isolation Level is Serializable. I've also tried ReadCommited and ReadUncommited, but they both error :- ReadCommited: same as above. Deadlock. ReadUncommited: different error. EF exception that says it expected some result back, but got nothing. I'm guessing this is the LogEntryId Identity (scope_identity) value that is expected but not retrieve because of the dirty read. Please help! PS. It's Sql Server 2008, btw.

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  • Working around MySQL error "Deadlock found when trying to get lock; try restarting transaction"

    - by Anon Guy
    Hi all: I have a MySQL table with about 5,000,000 rows that are being constantly updated in small ways by parallel Perl processes connecting via DBI. The table has about 10 columns and several indexes. One fairly common operation gives rise to the following error sometimes: DBD::mysql::st execute failed: Deadlock found when trying to get lock; try restarting transaction at Db.pm line 276. The SQL statement that triggers the error is something like this: UPDATE file_table SET a_lock = 'process-1234' WHERE param1 = 'X' AND param2 = 'Y' AND param3 = 'Z' LIMIT 47 The error is triggered only sometimes. I'd estimate in 1% of calls or less. However, it never happened with a small table and has become more common as the database has grown. Note that I am using the a_lock field in file_table to ensure that the four near-identical processes I am running do not try and work on the same row. The limit is designed to break their work into small chunks. I haven't done much tuning on MySQL or DBD::mysql. MySQL is a standard Solaris deployment, and the database connection is set up as follows: my $dsn = "DBI:mysql:database=" . $DbConfig::database . ";host=${DbConfig::hostname};port=${DbConfig::port}"; my $dbh = DBI->connect($dsn, $DbConfig::username, $DbConfig::password, { RaiseError => 1, AutoCommit => 1 }) or die $DBI::errstr; I have seen online that several other people have reported similar errors and that this may be a genuine deadlock situation. I have two questions: What exactly about my situation is causing the error above? Is there a simple way to work around it or lessen its frequency? For example, how exactly do I go about "restarting transaction at Db.pm line 276"? Thanks in advance.

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  • Identifying and Resolving Oracle ITL Deadlock

    - by Allan
    I have an Oracle DB package that is routinely causing what I believe is an ITL (Interested Transaction List) deadlock. The relevant portion of a trace file is below. Deadlock graph: ---------Blocker(s)-------- ---------Waiter(s)--------- Resource Name process session holds waits process session holds waits TM-0000cb52-00000000 22 131 S 23 143 SS TM-0000ceec-00000000 23 143 SX 32 138 SX SSX TM-0000cb52-00000000 30 138 SX 22 131 S session 131: DID 0001-0016-00000D1C session 143: DID 0001-0017-000055D5 session 143: DID 0001-0017-000055D5 session 138: DID 0001-001E-000067A0 session 138: DID 0001-001E-000067A0 session 131: DID 0001-0016-00000D1C Rows waited on: Session 143: no row Session 138: no row Session 131: no row There are no bit-map indexes on this table, so that's not the cause. As far as I can tell, the lack of "Rows waited on" plus the "S" in the Waiter waits column likely indicates that this is an ITL deadlock. Also, the table is written to quite often (roughly 8 insert or updates concurrently, as often as 240 times a minute), so and ITL deadlock seems like a strong possibility. I've increased the INITRANS parameter of the table and it's indexes to 100 and increased the PCT_FREE on the table from 10 to 20 (then rebuilt the indexes), but the deadlocks are still occurring. The deadlock seems to happen most often during an update, but that could just be a coincidence, as I've only traced it a couple of times. My questions are two-fold: 1) Is this actually an ITL deadlock? 2) If it is an ITL deadlock, what else can be done to avoid it?

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  • Reproducing a Conversion Deadlock

    - by Alexander Kuznetsov
    Even if two processes compete on only one resource, they still can embrace in a deadlock. The following scripts reproduce such a scenario. In one tab, run this: CREATE TABLE dbo.Test ( i INT ) ; GO INSERT INTO dbo.Test ( i ) VALUES ( 1 ) ; GO SET TRANSACTION ISOLATION LEVEL SERIALIZABLE ; BEGIN TRAN SELECT i FROM dbo.Test ; --UPDATE dbo.Test SET i=2 ; After this script has completed, we have an outstanding transaction holding a shared lock. In another tab, let us have that another connection have...(read more)

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  • Is it possible for competing file access to cause deadlock in Java?

    - by BlairHippo
    I'm chasing a production bug that's intermittent enough to be a real bastich to diagnose properly but frequent enough to be a legitimate nuisance for our customers. While I'm waiting for it to happen again on a machine set to spam the logfile with trace output, I'm trying to come up with a theory on what it could be. Is there any way for competing file read/writes to create what amounts to a deadlock condition? For instance, let's say I have Thread A that occasionally writes to config.xml, and Thread B that occasionally reads from it. Is there a set of circumstances that would cause Thread B to prevent Thread A from proceeding? My thanks in advance to anybody who helps with this theoretical fishing expedition. Edit: To answer Pyrolistical's questions: the code isn't using Filelock, and is running on a WinXP machine.

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  • Threads are facing deadlock in socket program [migrated]

    - by ankur.trapasiya
    I am developing one program in which a user can download a number of files. Now first I am sending the list of files to the user. So from the list user selects one file at a time and provides path where to store that file. In turn it also gives the server the path of file where does it exist. I am following this approach because I want to give stream like experience without file size limitation. Here is my code.. 1) This is server which gets started each time I start my application public class FileServer extends Thread { private ServerSocket socket = null; public FileServer() { try { socket = new ServerSocket(Utils.tcp_port); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } @Override public void run() { try { System.out.println("request received"); new FileThread(socket.accept()).start(); } catch (IOException ex) { ex.printStackTrace(); } } } 2) This thread runs for each client separately and sends the requested file to the user 8kb data at a time. public class FileThread extends Thread { private Socket socket; private String filePath; public String getFilePath() { return filePath; } public void setFilePath(String filePath) { this.filePath = filePath; } public FileThread(Socket socket) { this.socket = socket; System.out.println("server thread" + this.socket.isConnected()); //this.filePath = filePath; } @Override public void run() { // TODO Auto-generated method stub try { ObjectInputStream ois=new ObjectInputStream(socket.getInputStream()); try { //************NOTE filePath=(String) ois.readObject(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } File f = new File(this.filePath); byte[] buf = new byte[8192]; InputStream is = new FileInputStream(f); BufferedInputStream bis = new BufferedInputStream(is); ObjectOutputStream oos = new ObjectOutputStream( socket.getOutputStream()); int c = 0; while ((c = bis.read(buf, 0, buf.length)) > 0) { oos.write(buf, 0, c); oos.flush(); // buf=new byte[8192]; } oos.close(); //socket.shutdownOutput(); // client.shutdownOutput(); System.out.println("stop"); // client.shutdownOutput(); ois.close(); // Thread.sleep(500); is.close(); bis.close(); socket.close(); } catch (IOException ex) { ex.printStackTrace(); } } } NOTE: here filePath represents the path of the file where it exists on the server. The client who is connecting to the server provides this path. I am managing this through sockets and I am successfully receiving this path. 3) FileReceiverThread is responsible for receiving the data from the server and constructing file from this buffer data. public class FileReceiveThread extends Thread { private String fileStorePath; private String sourceFile; private Socket socket = null; public FileReceiveThread(String ip, int port, String fileStorePath, String sourceFile) { this.fileStorePath = fileStorePath; this.sourceFile = sourceFile; try { socket = new Socket(ip, port); System.out.println("receive file thread " + socket.isConnected()); } catch (IOException ex) { ex.printStackTrace(); } } @Override public void run() { try { ObjectOutputStream oos = new ObjectOutputStream( socket.getOutputStream()); oos.writeObject(sourceFile); oos.flush(); // oos.close(); File f = new File(fileStorePath); OutputStream os = new FileOutputStream(f); BufferedOutputStream bos = new BufferedOutputStream(os); byte[] buf = new byte[8192]; int c = 0; //************ NOTE ObjectInputStream ois = new ObjectInputStream( socket.getInputStream()); while ((c = ois.read(buf, 0, buf.length)) > 0) { // ois.read(buf); bos.write(buf, 0, c); bos.flush(); // buf = new byte[8192]; } ois.close(); oos.close(); // os.close(); bos.close(); socket.close(); //Thread.sleep(500); } catch (IOException ex) { ex.printStackTrace(); } } } NOTE : Now the problem that I am facing is at the first time when the file is requested the outcome of the program is same as my expectation. I am able to transmit any size of file at first time. Now when the second file is requested (e.g. I have sent file a,b,c,d to the user and user has received file a successfully and now he is requesting file b) the program faces deadlock at this situation. It is waiting for socket's input stream. I put breakpoint and tried to debug it but it is not going in FileThread's run method second time. I could not find out the mistake here. Basically I am making a LAN Messenger which works on LAN. I am using SWT as UI framework.

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  • What is causing this SQL 2005 Primary Key Deadlock between two real-time bulk upserts?

    - by skimania
    Here's the scenario: I've got a table called MarketDataCurrent (MDC) that has live updating stock prices. I've got one process called 'LiveFeed' which reads prices streaming from the wire, queues up inserts, and uses a 'bulk upload to temp table then insert/update to MDC table.' (BulkUpsert) I've got another process which then reads this data, computes other data, and then saves the results back into the same table, using a similar BulkUpsert stored proc. Thirdly, there are a multitude of users running a C# Gui polling the MDC table and reading updates from it. Now, during the day when the data is changing rapidly, things run pretty smoothly, but then, after market hours, we've recently started seeing an increasing number of Deadlock exceptions coming out of the database, nowadays we see 10-20 a day. The imporant thing to note here is that these happen when the values are NOT changing. Here's all the relevant info: Table Def: CREATE TABLE [dbo].[MarketDataCurrent]( [MDID] [int] NOT NULL, [LastUpdate] [datetime] NOT NULL, [Value] [float] NOT NULL, [Source] [varchar](20) NULL, CONSTRAINT [PK_MarketDataCurrent] PRIMARY KEY CLUSTERED ( [MDID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] - stackoverflow wont let me post images until my reputation goes up to 10, so i'll add them as soon as you bump me up, hopefully as a result of this question. ![alt text][1] [1]: http://farm5.static.flickr.com/4049/4690759452_6b94ff7b34.jpg I've got a Sql Profiler Trace Running, catching the deadlocks, and here's what all the graphs look like. stackoverflow wont let me post images until my reputation goes up to 10, so i'll add them as soon as you bump me up, hopefully as a result of this question. ![alt text][2] [2]: http://farm5.static.flickr.com/4035/4690125231_78d84c9e15_b.jpg Process 258 is called the following 'BulkUpsert' stored proc, repeatedly, while 73 is calling the next one: ALTER proc [dbo].[MarketDataCurrent_BulkUpload] @updateTime datetime, @source varchar(10) as begin transaction update c with (rowlock) set LastUpdate = getdate(), Value = t.Value, Source = @source from MarketDataCurrent c INNER JOIN #MDTUP t ON c.MDID = t.mdid where c.lastUpdate < @updateTime and c.mdid not in (select mdid from MarketData where LiveFeedTicker is not null and PriceSource like 'LiveFeed.%') and c.value <> t.value insert into MarketDataCurrent with (rowlock) select MDID, getdate(), Value, @source from #MDTUP where mdid not in (select mdid from MarketDataCurrent with (nolock)) and mdid not in (select mdid from MarketData where LiveFeedTicker is not null and PriceSource like 'LiveFeed.%') commit And the other one: ALTER PROCEDURE [dbo].[MarketDataCurrent_LiveFeedUpload] AS begin transaction -- Update existing mdid UPDATE c WITH (ROWLOCK) SET LastUpdate = t.LastUpdate, Value = t.Value, Source = t.Source FROM MarketDataCurrent c INNER JOIN #TEMPTABLE2 t ON c.MDID = t.mdid; -- Insert new MDID INSERT INTO MarketDataCurrent with (ROWLOCK) SELECT * FROM #TEMPTABLE2 WHERE MDID NOT IN (SELECT MDID FROM MarketDataCurrent with (NOLOCK)) -- Clean up the temp table DELETE #TEMPTABLE2 commit To clarify, those Temp Tables are being created by the C# code on the same connection and are populated using the C# SqlBulkCopy class. To me it looks like it's deadlocking on the PK of the table, so I tried removing that PK and switching to a Unique Constraint instead but that increased the number of deadlocks 10-fold. I'm totally lost as to what to do about this situation and am open to just about any suggestion. HELP!!

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  • Deadlock in SQL Server 2005! Two real-time bulk upserts are fighting. WHY?

    - by skimania
    Here's the scenario: I've got a table called MarketDataCurrent (MDC) that has live updating stock prices. I've got one process called 'LiveFeed' which reads prices streaming from the wire, queues up inserts, and uses a 'bulk upload to temp table then insert/update to MDC table.' (BulkUpsert) I've got another process which then reads this data, computes other data, and then saves the results back into the same table, using a similar BulkUpsert stored proc. Thirdly, there are a multitude of users running a C# Gui polling the MDC table and reading updates from it. Now, during the day when the data is changing rapidly, things run pretty smoothly, but then, after market hours, we've recently started seeing an increasing number of Deadlock exceptions coming out of the database, nowadays we see 10-20 a day. The imporant thing to note here is that these happen when the values are NOT changing. Here's all the relevant info: Table Def: CREATE TABLE [dbo].[MarketDataCurrent]( [MDID] [int] NOT NULL, [LastUpdate] [datetime] NOT NULL, [Value] [float] NOT NULL, [Source] [varchar](20) NULL, CONSTRAINT [PK_MarketDataCurrent] PRIMARY KEY CLUSTERED ( [MDID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] - I've got a Sql Profiler Trace Running, catching the deadlocks, and here's what all the graphs look like. Process 258 is called the following 'BulkUpsert' stored proc, repeatedly, while 73 is calling the next one: ALTER proc [dbo].[MarketDataCurrent_BulkUpload] @updateTime datetime, @source varchar(10) as begin transaction update c with (rowlock) set LastUpdate = getdate(), Value = t.Value, Source = @source from MarketDataCurrent c INNER JOIN #MDTUP t ON c.MDID = t.mdid where c.lastUpdate < @updateTime and c.mdid not in (select mdid from MarketData where LiveFeedTicker is not null and PriceSource like 'LiveFeed.%') and c.value <> t.value insert into MarketDataCurrent with (rowlock) select MDID, getdate(), Value, @source from #MDTUP where mdid not in (select mdid from MarketDataCurrent with (nolock)) and mdid not in (select mdid from MarketData where LiveFeedTicker is not null and PriceSource like 'LiveFeed.%') commit And the other one: ALTER PROCEDURE [dbo].[MarketDataCurrent_LiveFeedUpload] AS begin transaction -- Update existing mdid UPDATE c WITH (ROWLOCK) SET LastUpdate = t.LastUpdate, Value = t.Value, Source = t.Source FROM MarketDataCurrent c INNER JOIN #TEMPTABLE2 t ON c.MDID = t.mdid; -- Insert new MDID INSERT INTO MarketDataCurrent with (ROWLOCK) SELECT * FROM #TEMPTABLE2 WHERE MDID NOT IN (SELECT MDID FROM MarketDataCurrent with (NOLOCK)) -- Clean up the temp table DELETE #TEMPTABLE2 commit To clarify, those Temp Tables are being created by the C# code on the same connection and are populated using the C# SqlBulkCopy class. To me it looks like it's deadlocking on the PK of the table, so I tried removing that PK and switching to a Unique Constraint instead but that increased the number of deadlocks 10-fold. I'm totally lost as to what to do about this situation and am open to just about any suggestion. HELP!! In response to the request for the XDL, here it is: <deadlock-list> <deadlock victim="processc19978"> <process-list> <process id="processaf0b68" taskpriority="0" logused="0" waitresource="KEY: 6:72057594090487808 (d900ed5a6cc6)" waittime="718" ownerId="1102128174" transactionname="user_transaction" lasttranstarted="2010-06-11T16:30:44.750" XDES="0xffffffff817f9a40" lockMode="U" schedulerid="3" kpid="8228" status="suspended" spid="73" sbid="0" ecid="0" priority="0" transcount="2" lastbatchstarted="2010-06-11T16:30:44.750" lastbatchcompleted="2010-06-11T16:30:44.750" clientapp=".Net SqlClient Data Provider" hostname="RISKAPPS_VM" hostpid="3836" loginname="RiskOpt" isolationlevel="read committed (2)" xactid="1102128174" currentdb="6" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056"> <executionStack> <frame procname="MKP_RISKDB.dbo.MarketDataCurrent_BulkUpload" line="28" stmtstart="1062" stmtend="1720" sqlhandle="0x03000600a28e5e4ef4fd8e00849d00000100000000000000"> UPDATE c WITH (ROWLOCK) SET LastUpdate = getdate(), Value = t.Value, Source = @source FROM MarketDataCurrent c INNER JOIN #MDTUP t ON c.MDID = t.mdid WHERE c.lastUpdate &lt; @updateTime and c.mdid not in (select mdid from MarketData where BloombergTicker is not null and PriceSource like &apos;Blbg.%&apos;) and c.value &lt;&gt; t.value </frame> <frame procname="adhoc" line="1" stmtstart="88" sqlhandle="0x01000600c1653d0598706ca7000000000000000000000000"> exec MarketDataCurrent_BulkUpload @clearBefore, @source </frame> <frame procname="unknown" line="1" sqlhandle="0x000000000000000000000000000000000000000000000000"> unknown </frame> </executionStack> <inputbuf> (@clearBefore datetime,@source nvarchar(10))exec MarketDataCurrent_BulkUpload @clearBefore, @source </inputbuf> </process> <process id="processc19978" taskpriority="0" logused="0" waitresource="KEY: 6:72057594090487808 (74008e31572b)" waittime="718" ownerId="1102128228" transactionname="user_transaction" lasttranstarted="2010-06-11T16:30:44.780" XDES="0x380be9d8" lockMode="U" schedulerid="5" kpid="8464" status="suspended" spid="248" sbid="0" ecid="0" priority="0" transcount="2" lastbatchstarted="2010-06-11T16:30:44.780" lastbatchcompleted="2010-06-11T16:30:44.780" clientapp=".Net SqlClient Data Provider" hostname="RISKBBG_VM" hostpid="4480" loginname="RiskOpt" isolationlevel="read committed (2)" xactid="1102128228" currentdb="6" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056"> <executionStack> <frame procname="MKP_RISKDB.dbo.MarketDataCurrentBlbgRtUpload" line="14" stmtstart="840" stmtend="1220" sqlhandle="0x03000600005f9d24c8878f00849d00000100000000000000"> UPDATE c WITH (ROWLOCK) SET LastUpdate = t.LastUpdate, Value = t.Value, Source = t.Source FROM MarketDataCurrent c INNER JOIN #TEMPTABLE2 t ON c.MDID = t.mdid; -- Insert new MDID </frame> <frame procname="adhoc" line="1" sqlhandle="0x010006004a58132228bf8d73000000000000000000000000"> MarketDataCurrentBlbgRtUpload </frame> </executionStack> <inputbuf> MarketDataCurrentBlbgRtUpload </inputbuf> </process> </process-list> <resource-list> <keylock hobtid="72057594090487808" dbid="6" objectname="MKP_RISKDB.dbo.MarketDataCurrent" indexname="PK_MarketDataCurrent" id="lock5ba77b00" mode="U" associatedObjectId="72057594090487808"> <owner-list> <owner id="processc19978" mode="U"/> </owner-list> <waiter-list> <waiter id="processaf0b68" mode="U" requestType="wait"/> </waiter-list> </keylock> <keylock hobtid="72057594090487808" dbid="6" objectname="MKP_RISKDB.dbo.MarketDataCurrent" indexname="PK_MarketDataCurrent" id="lock65dca340" mode="U" associatedObjectId="72057594090487808"> <owner-list> <owner id="processaf0b68" mode="U"/> </owner-list> <waiter-list> <waiter id="processc19978" mode="U" requestType="wait"/> </waiter-list> </keylock> </resource-list> </deadlock> </deadlock-list>

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