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  • How to rate-limit concurrent sessions with nginx or haproxy?

    - by bantic
    I'm currently using nginx to reverse-proxy requests from web clients that are doing long-polling to an upstream. Since we're doing long polling (as opposed to websockets), when a client connects it will make multiple http connections to the server in serial, re-establishing a connection every time the server sends it some data (or timing out and re-establishing if the server has nothing to say for 10 seconds). What I'd like to do is limit the number of concurrent web clients. Since the clients are constantly making new HTTP requests instead of keeping a single request open, it's a little tricky to count the total number of web clients (because it's not the same as total number of concurrently connected http clients). The method I've come up with is to track http requests by the originating IP address, and store the IP address somewhere with a TTL of 20 seconds. If a request comes in whose IP isn't recognized, then we check the total number of unexpired stored IP addresses; if that's less than the maximum then we allow this request through. And if a request comes in with an IP address that we can find in the look-up table that hasn't yet expired, then it is allowed through as well. All requests that are allowed through have their IPs added to the table (if not there before) and the TTL refreshed to 20 seconds again. I had actually whipped something together that worked correctly this way using nginx along with the Redis 2.0 Nginx Module (and the nginx lua module to simplify the conditional branching), using redis to store my IP addresses with a TTL (the SETEX command), and checking the table size with the DBSIZE command. This worked but the performance was horrible. nginx and redis ended up using lots of cpu and the machine could only handle a very small number of concurrent requests. The new stick-table and tracking counters that were added to Haproxy in version 1.5 (via a commission from serverfault) seem like they might be ideal to implement exactly this sort of rate limiting, because the stick-table can track IP addresses and automatically expire entries. However, I don't see an easy way to get a total count of the unexpired entries in the stick table, which would be necessary to know the number of connected web clients. I'm curious if anyone has any suggestions, for nginx or haproxy or even for something else not mentioned here that I haven't thought of yet.

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  • BizTalk and SQL: Alternatives to the SQL receive adapter. Using Msmq to receive SQL data

    - by Leonid Ganeline
    If we have to get data from the SQL database, the standard way is to use a receive port with SQL adapter. SQL receive adapter is a solicit-response adapter. It periodically polls the SQL database with queries. That’s only way it can work. Sometimes it is undesirable. With new WCF-SQL adapter we can use the lightweight approach but still with the same principle, the WCF-SQL adapter periodically solicits the database with queries to check for the new records. Imagine the situation when the new records can appear in very broad time limits, some - in a second interval, others - in the several minutes interval. Our requirement is to process the new records ASAP. That means the polling interval should be near the shortest interval between the new records, a second interval. As a result the most of the poll queries would return nothing and would load the database without good reason. If the database is working under heavy payload, it is very undesirable. Do we have other choices? Sure. We can change the polling to the “eventing”. The good news is the SQL server could issue the event in case of new records with triggers. Got a new record –the trigger event is fired. No new records – no the trigger events – no excessive load to the database. The bad news is the SQL Server doesn’t have intrinsic methods to send the event data outside. For example, we would rather use the adapters that do listen for the data and do not solicit. There are several such adapters-listeners as File, Ftp, SOAP, WCF, and Msmq. But the SQL Server doesn’t have methods to create and save files, to consume the Web-services, to create and send messages in the queue, does it? Can we use the File, FTP, Msmq, WCF adapters to get data from SQL code? Yes, we can. The SQL Server 2005 and 2008 have the possibility to use .NET code inside SQL code. See the SQL Integration. How it works for the Msmq, for example: ·         New record is created, trigger is fired ·         Trigger calls the CLR stored procedure and passes the message parameters to it ·         The CLR stored procedure creates message and sends it to the outgoing queue in the SQL Server computer. ·         Msmq service transfers message to the queue in the BizTalk Server computer. ·         WCF-NetMsmq adapter receives the message from this queue. For the File adapter the idea is the same, the CLR stored procedure creates and stores the file with message, and then the File adapter picks up this file. Using WCF-NetMsmq adapter to get data from SQL I am describing the full set of the deployment and development steps for the case with the WCF-NetMsmq adapter. Development: 1.       Create the .NET code: project, class and method to create and send the message to the MSMQ queue. 2.       Create the SQL code in triggers to call the .NET code. Installation and Deployment: 1.       SQL Server: a.       Register the CLR assembly with .NET (CLR) code b.      Install the MSMQ Services 2.       BizTalk Server: a.       Install the MSMQ Services b.      Create the MSMQ queue c.       Create the WCF-NetMsmq receive port. The detailed description is below. Code .NET code … using System.Xml; using System.Xml.Linq; using System.Xml.Serialization;   //namespace MyCompany.MySolution.MyProject – doesn’t work. The assembly name is MyCompany.MySolution.MyProject // I gave up with the compound namespace. Seems the CLR Integration cannot work with it L. Maybe I’m wrong.     public class Event     {         static public XElement CreateMsg(int par1, int par2, int par3)         {             XNamespace ns = "http://schemas.microsoft.com/Sql/2008/05/TypedPolling/my_storedProc";             XElement xdoc =                 new XElement(ns + "TypedPolling",                     new XElement(ns + "TypedPollingResultSet0",                         new XElement(ns + "TypedPollingResultSet0",                             new XElement(ns + "par1", par1),                             new XElement(ns + "par2", par2),                             new XElement(ns + "par3", par3),                         )                     )                 );             return xdoc;         }     }   //////////////////////////////////////////////////////////////////////// … using System.ServiceModel; using System.ServiceModel.Channels; using System.Transactions; using System.Data; using System.Data.Sql; using System.Data.SqlTypes;   public class MsmqHelper {     [Microsoft.SqlServer.Server.SqlProcedure]     // msmqAddress as "net.msmq://localhost/private/myapp.myqueue";     public static void SendMsg(string msmqAddress, string action, int par1, int par2, int par3)     {         using (TransactionScope scope = new TransactionScope(TransactionScopeOption.Suppress))         {             NetMsmqBinding binding = new NetMsmqBinding(NetMsmqSecurityMode.None);             binding.ExactlyOnce = true;             EndpointAddress address = new EndpointAddress(msmqAddress);               using (ChannelFactory<IOutputChannel> factory = new ChannelFactory<IOutputChannel>(binding, address))             {                 IOutputChannel channel = factory.CreateChannel();                 try                 {                     XElement xe = Event.CreateMsg(par1, par2, par3);                     XmlReader xr = xe.CreateReader();                     Message msg = Message.CreateMessage(MessageVersion.Default, action, xr);                     channel.Send(msg);                     //SqlContext.Pipe.Send(…); // to test                 }                 catch (Exception ex)                 { …                 }             }             scope.Complete();         }     }   SQL code in triggers   -- sp_SendMsg was registered as a name of the MsmqHelper.SendMsg() EXEC sp_SendMsg'net.msmq://biztalk_server_name/private/myapp.myqueue', 'Create', @par1, @par2, @par3   Installation and Deployment On the SQL Server Registering the CLR assembly 1.       Prerequisites: .NET 3.5 SP1 Framework. It could be the issue for the production SQL Server! 2.       For more information, please, see the link http://nielsb.wordpress.com/sqlclrwcf/ 3.       Copy files: >copy “\Windows\Microsoft.net\Framework\v3.0\Windows Communication Foundation\Microsoft.Transactions.Bridge.dll” “\Program Files\Reference Assemblies\Microsoft\Framework\v3.0 \Microsoft.Transactions.Bridge.dll” If your machine is a 64-bit, run two commands: >copy “\Windows\Microsoft.net\Framework\v3.0\Windows Communication Foundation\Microsoft.Transactions.Bridge.dll” “\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.0 \Microsoft.Transactions.Bridge.dll” >copy “\Windows\Microsoft.net\Framework64\v3.0\Windows Communication Foundation\Microsoft.Transactions.Bridge.dll” “\Program Files\Reference Assemblies\Microsoft\Framework\v3.0 \Microsoft.Transactions.Bridge.dll” 4.       Execute the SQL code to register the .NET assemblies: -- For x64 OS: CREATE ASSEMBLY SMdiagnostics AUTHORIZATION dbo FROM 'C:\Windows\Microsoft.NET\Framework\v3.0\Windows Communication Foundation\SMdiagnostics.dll' WITH permission_set = unsafe CREATE ASSEMBLY [System.Web] AUTHORIZATION dbo FROM 'C:\Windows\Microsoft.NET\Framework64\v2.0.50727\System.Web.dll' WITH permission_set = unsafe CREATE ASSEMBLY [System.Messaging] AUTHORIZATION dbo FROM 'C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Messaging.dll' WITH permission_set = unsafe CREATE ASSEMBLY [System.ServiceModel] AUTHORIZATION dbo FROM 'C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.0\System.ServiceModel.dll' WITH permission_set = unsafe CREATE ASSEMBLY [System.Xml.Linq] AUTHORIZATION dbo FROM 'C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.5\System.Xml.Linq.dll' WITH permission_set = unsafe   -- For x32 OS: --CREATE ASSEMBLY SMdiagnostics AUTHORIZATION dbo FROM 'C:\Windows\Microsoft.NET\Framework\v3.0\Windows Communication Foundation\SMdiagnostics.dll' WITH permission_set = unsafe --CREATE ASSEMBLY [System.Web] AUTHORIZATION dbo FROM 'C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Web.dll' WITH permission_set = unsafe --CREATE ASSEMBLY [System.Messaging] AUTHORIZATION dbo FROM 'C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Messaging.dll' WITH permission_set = unsafe --CREATE ASSEMBLY [System.ServiceModel] AUTHORIZATION dbo FROM 'C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.0\System.ServiceModel.dll' WITH permission_set = unsafe 5.       Register the assembly with the external stored procedure: CREATE ASSEMBLY [HelperClass] AUTHORIZATION dbo FROM ’<FilePath>MyCompany.MySolution.MyProject.dll' WITH permission_set = unsafe where the <FilePath> - the path of the file on this machine! 6. Create the external stored procedure CREATE PROCEDURE sp_SendMsg (        @msmqAddress nvarchar(100),        @Action NVARCHAR(50),        @par1 int,        @par2 int,        @par3 int ) AS EXTERNAL NAME HelperClear.MsmqHelper.SendMsg   Installing the MSMQ Services 1.       Check if the MSMQ service is NOT installed. To check:  Start / Administrative Tools / Computer Management, on the left pane open the “Services and Applications”, search to the “Message Queuing”. If you cannot see it, follow next steps. 2.       Start / Control Panel / Programs and Features 3.       Click “Turn Windows Features on or off” 4.       Click Features, click “Add Features” 5.       Scroll down the feature list; open the “Message Queuing” / “Message Queuing Services”; and check the “Message Queuing Server” option  6.       Click Next; Click Install; wait to the successful finish of the installation Creating the MSMQ queue We don’t need to create the queue on the “sender” side. On the BizTalk Server Installing the MSMQ Services The same is as for the SQL Server. Creating the MSMQ queue 1.       Start / Administrative Tools / Computer Management, on the left pane open the “Services and Applications”, open the “Message Queuing”, and open the “Private Queues”. 2.       Right-click the “Private Queues”; choose New; choose “Private Queue”. 3.       Type the Queue name as ’myapp.myqueue'; check the “Transactional” option. Creating the WCF-NetMsmq receive port I will not go through this step in all details. It is straightforward. URI for this receive location should be 'net.msmq://localhost/private/myapp.myqueue'. Notes ·         The biggest problem is usually on the step the “Registering the CLR assembly”. It is hard to predict where are the assemblies from the assembly list, what version should be used, x86 or x64. It is pity of such “rude” integration of the SQL with .NET. ·         In couple cases the new WCF-NetMsmq port was not able to work with the queue. Try to replace the WCF- NetMsmq port with the WCF-Custom port with netMsmqBinding. It was working fine for me. ·         To test how messages go through the queue you can turn on the Journal /Enabled option for the queue. I used the QueueExplorer utility to look to the messages in Journal. The Computer Management can also show the messages but it shows only small part of the message body and in the weird format. The QueueExplorer can do the better job; it shows the whole body and Xml messages are in good color format.

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  • How to get local ActiveMQ broker to "mirror" a queue on a remote ActiveMQ broker?

    - by T.K.
    I have a local ActiveMQ broker which is on an unreliable internet connection, and also a remote ActiveMQ broker in a reliable datacenter. I have already sorted out a "store and forward" setup so that outgoing messages are sent to the remote broker when the Internet connection is available. That alone works great, but when messages are outbound. However, now I have to do the reverse. Here is the scenario: A new message appears in the remote ActiveMQ broker. The message is put into a specific queue. In a few minutes, the Internet connection becomes available to the local ActiveMQ broker. The local broker should then be able to pull the message from the remote broker, and place it in its own local queue. Local consumers will then be able to see the message. So in essence, I need the local broker to become a subscribed consumer to the remote queue. I have looked through the ActiveMQ documentations but I can't find anything yet about how to do this in the .xml configuration file. Is this what I should be looking for? See: "ActiveMQ: JMS to JMS Bridge". Any advice and tips would be highly appreciated.

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  • How (and if) to write a single-consumer queue using the task parallel library?

    - by Eric
    I've heard a bunch of podcasts recently about the TPL in .NET 4.0. Most of them describe background activities like downloading images or doing a computation, using tasks so that the work doesn't interfere with a GUI thread. Most of the code I work on has more of a multiple-producer / single-consumer flavor, where work items from multiple sources must be queued and then processed in order. One example would be logging, where log lines from multiple threads are sequentialized into a single queue for eventual writing to a file or database. All the records from any single source must remain in order, and records from the same moment in time should be "close" to each other in the eventual output. So multiple threads or tasks or whatever are all invoking a queuer: lock( _queue ) // or use a lock-free queue! { _queue.enqueue( some_work ); _queueSemaphore.Release(); } And a dedicated worker thread processes the queue: while( _queueSemaphore.WaitOne() ) { lock( _queue ) { some_work = _queue.dequeue(); } deal_with( some_work ); } It's always seemed reasonable to dedicate a worker thread for the consumer side of these tasks. Should I write future programs using some construct from the TPL instead? Which one? Why?

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  • Mocking successive calls of similar type via sequential mocking

    - by mehfuzh
    In this post , i show how you can benefit from  sequential mocking feature[In JustMock] for setting up expectations with successive calls of same type.  To start let’s first consider the following dummy database and entity class. public class Person {     public virtual string Name { get; set; }     public virtual int Age { get; set; } }   public interface IDataBase {     T Get<T>(); } Now, our test goal is to return different entity for successive calls on IDataBase.Get<T>(). By default, the behavior in JustMock is override , which is similar to other popular mocking tools. By override it means that the tool will consider always the latest user setup. Therefore, the first example will return the latest entity every-time and will fail in line #12: Person person1 = new Person { Age = 30, Name = "Kosev" }; Person person2 = new Person { Age = 80, Name = "Mihail" };   var database = Mock.Create<IDataBase>();   Queue<Person> queue = new Queue<Person>();   Mock.Arrange(() => database.Get<Person>()).Returns(() => queue.Dequeue()); Mock.Arrange(() => database.Get<Person>()).Returns(person2);   // this will fail Assert.Equal(person1.GetHashCode(), database.Get<Person>().GetHashCode());   Assert.Equal(person2.GetHashCode(), database.Get<Person>().GetHashCode()); We can solve it the following way using a Queue and that removes the item from bottom on each call: Person person1 = new Person { Age = 30, Name = "Kosev" }; Person person2 = new Person { Age = 80, Name = "Mihail" };   var database = Mock.Create<IDataBase>();   Queue<Person> queue = new Queue<Person>();   queue.Enqueue(person1); queue.Enqueue(person2);   Mock.Arrange(() => database.Get<Person>()).Returns(queue.Dequeue());   Assert.Equal(person1.GetHashCode(), database.Get<Person>().GetHashCode()); Assert.Equal(person2.GetHashCode(), database.Get<Person>().GetHashCode()); This will ensure that right entity is returned but this is not an elegant solution. So, in JustMock we introduced a  new option that lets you set up your expectations sequentially. Like: Person person1 = new Person { Age = 30, Name = "Kosev" }; Person person2 = new Person { Age = 80, Name = "Mihail" };   var database = Mock.Create<IDataBase>();   Mock.Arrange(() => database.Get<Person>()).Returns(person1).InSequence(); Mock.Arrange(() => database.Get<Person>()).Returns(person2).InSequence();   Assert.Equal(person1.GetHashCode(), database.Get<Person>().GetHashCode()); Assert.Equal(person2.GetHashCode(), database.Get<Person>().GetHashCode()); The  “InSequence” modifier will tell the mocking tool to return the expected result as in the order it is specified by user. The solution though pretty simple and but neat(to me) and way too simpler than using a collection to solve this type of cases. Hope that helps P.S. The example shown in my blog is using interface don’t require a profiler  and you can even use a notepad and build it referencing Telerik.JustMock.dll, run it with GUI tools and it will work. But this feature also applies to concrete methods that includes JM profiler and can be implemented for more complex scenarios.

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  • Are there any "traps" in cloning a VirtualBox VM for concurrent use on the same Host/LAN?

    - by fred.bear
    With Ubuntu as the Host, I want to run two similar/identical(?) instances of a VirtualBox Guest on the same Host, or perhaps on another Host which is on the same LAN... I have set up a Guest as a "base" for the two clones. I have exported it as an ovf appliance. I've imported this "base" guest OS back into VirtualBox, with a unique name and .vdk ... and I have started them both on the same Host, and all seems okay, but I do wonder if I have missed some significant point. ...eg. Is the virtual NIC the same? this would throw the LAN into confusion (I think)... and what about UUIDs? I haven't actually tried 2 clones together, yet... only the original and one clone, but I haven't gone beyond a simple startup ...

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  • How to get Messages Pending Count from a Queue using WLST?

    - by lmestre
    WLST is a scripting Language that helps to achieve similar functionality as the ones you have in WebLogic console, but in a command line fashion.You can develop your WLST Scripts using Eclipse OEPE, read more here:https://blogs.oracle.com/oepe/entry/new_oracle_enterprise_pack_forFinally, here is an example to get Messages Pending Count using WLST: . ./setDomainEnv.sh java weblogic.WLST connect('weblogic','welcome1','t3://localhost:7001') domainRuntime() jms= getMBean ('ServerRuntimes/MyManagedServer/JMSRuntime/MyManagedServer.jms/JMSServers/MyJMSServer/Destinations/MyModule!MyQueue') jms.getMessagesPendingCount() Enjoy!WLST documentation:http://docs.oracle.com/middleware/1212/wls/WLSTG/index.html

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  • How to resolve concurrent ramp collisions in 2d platformer?

    - by Shaun Inman
    A bit about the physics engine: Bodies are all rectangles. Bodies are sorted at the beginning of every update loop based on the body-in-motion's horizontal and vertical velocity (to avoid sticky walls/floors). Solid bodies are resolved by testing the body-in-motion's new X with the old Y and adjusting if necessary before testing the new X with the new Y, again adjusting if necessary. Works great. Ramps (rectangles with a flag set indicating bottom-left, bottom-right, etc) are resolved by calculating the ratio of penetration along the x-axis and setting a new Y accordingly (with some checks to make sure the body-in-motion isn't attacking from the tall or flat side, in which case the ramp is treated as a normal rectangle). This also works great. Side-by-side ramps, eg. \/ and /\, work fine but things get jittery and unpredictable when a top-down ramp is directly above a bottom-up ramp, eg. < or > or when a bottom-up ramp runs right up to the ceiling/top-down ramp runs right down to the floor. I've been able to lock it down somewhat by detecting whether the body-in-motion hadFloor when also colliding with a top-down ramp or hadCeiling when also colliding with a bottom-up ramp then resolving by calculating the ratio of penetration along the y-axis and setting the new X accordingly (the opposite of the normal behavior). But as soon as the body-in-motion jumps the hasFloor flag becomes false, the first ramp resolution pushes the body into collision with the second ramp and collision resolution becomes jittery again for a few frames. I'm sure I'm making this more complicated than it needs to be. Can anyone recommend a good resource that outlines the best way to address this problem? (Please don't recommend I use something like Box2d or Chipmunk. Also, "redesign your levels" isn't an answer; the body-in-motion may at times be riding another body-in-motion, eg. a platform, that pushes it into a ramp so I'd like to be able to resolve this properly.) Thanks!

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  • What are the recommended resources for learning about the Actor model of concurrent systems?

    - by Larry OBrien
    The Actor concurrency model is clearly gaining favor. Is there a good book that presents the patterns and pitfalls of the model? I am thinking about something that would discuss, for instance, the problems of consistency and correctness in the context of hundreds or thousands of independent Actors. It would be okay if it were associated with a specific language (Erlang, I would imagine, since that seems universally regarded as the proven implementation of Actors), but I am hoping for something more than an introductory chapter or two. I'm actually most interested in Actors as they are implemented in Scala, if there are any such resources available.

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  • Les conditions de travail chez Foxconn toujours aussi mauvaises d'après une ONG, un concurrent d'Apple pourrait en profiter

    Les conditions de travail chez Foxconn seraient toujours aussi mauvaises D'après le China Labour Bulletin, la polémique autour du fournisseur d'Apple peut-elle affecter la marque ? Le sous-traitant informatique Foxconn continue de faire parler de lui. Ce géant taïwanais, qui emploie plus de 1.2 millions de collaborateurs, assemble les produits de grands noms de l'électronique à l'instar de Apple, HP, Nintendo, Sony, Microsoft ou encore Amazon. Une vague de suicides à répétition avait placé Foxconn sous le feu des projecteurs en 2010 et 3 employés ont trouvé la mort en juin dernier dans une explosion à l'usine de Chengdu. Foxconn a vu sa réputation s'écrouler aux Etats-Unis ...

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  • Microsoft apporte le support du H.264 à Firefox avec une extension qui permet de gérer le codec propriétaire concurrent du WebM

    Microsoft publie une extension pour Firefox Qui permet le support de la vidéo H.264 Microsoft confirme une fois de plus son soutien au nouveau standard du web le HTML5. Après le support de la norme dans son future navigateur Internet Explorer 9 et son moteur de recherche Bing, la firme de Redmond vient de publier une extension en rapport avec ce standard pour... FireFox. Cette extension permettant aux utilisateurs de Firefox sur Windows 7 de regarder des vidéos au format H.264, un codec p...

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  • How to limit concurrent file access on a Samba share?

    - by JPbuntu
    I have a Ubuntu 12.04 file server running Samba. There are 6 windows machines that access the server, as well as two people that will occasionally access files remotely. The problem that I am having is that the CAD/CAM software we are using doesn't seem to request file locks, meaning if two people open a file at the same time, the first person to close the file will get their changes overwritten if the second person saves the file. I tried changing the smb.conf to strict locking = yes but this doesn't seem to have any effect. File locking with excel seems to work fine, so I know that Samba is using the file locks...if they were put on the file in the first place. Is there a way (either in Samba or Ubuntu) to only allow one user to have a file open at a time? If not does anyone have any suggestions for managing a problem like this?

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  • Microsoft préparerait son concurrent des Google Glass, la montre connectée de la société serait en phase de test

    Bientôt des "Microsoft Glass" ? C'est ce qu'affirme un billet sur le blog du Wall Street Journal. La firme de Redmond aurait dans les cartons un projet de lunette connectée comparable aux Google Glass.Le Wall Street Journal affirme que plusieurs fournisseurs chinois auraient été contactés pour mettre au point ces lunettes.Une montre connectée serait également dans les cartons de Microsoft, qui tente de rattraper son retard dans le virage du mobile. Source : Wall Street Journal Microsoft...

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  • How do you manage private queue permissions on a windows server 2008 cluster?

    - by David
    On windows server 2003 there was an option to allow a resource to interact with the desktop, this allowed you to run computer management mmc snap-in on the virtual name of the cluster, allowing you to manage permissions of the private message queues on the cluster. Windows Server 2008 failover clustering has removed that checkbox, so applications can no longer interact with the desktop. My question is then how does one go about managing private queue permissions on the clustered (the virtual name) server?

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  • Server compromised. Bounce message contains many email addresses message was not sent to

    - by Tim Duncklee
    This is not a dupe. Please read and understand the issue before marking this as a duplicate question that has been answered already. Several customers are reporting bounce messages like the one below. At first I thought their computers had a virus but then I received one that was server generated so the problem is with the server. I've inspected the logs and these email addresses do not appear in the logs. The only thing I see that I do not remember seeing in the past are entries like this: Apr 30 13:34:49 psa86 qmail-queue-handlers[20994]: hook_dir = '/var/qmail//handlers/before-queue' Apr 30 13:34:49 psa86 qmail-queue-handlers[20994]: recipient[3] = '[email protected]' Apr 30 13:34:49 psa86 qmail-queue-handlers[20994]: handlers dir = '/var/qmail//handlers/before-queue/recipient/[email protected]' I've searched here and the web and maybe I'm just not entering the right search terms but I find nothing on this issue. Does anyone know how a hacker would attach additional email addresses to a message at the server and have them not appear in the logs? CentOS release 5.4, Plesk 8.6, QMail 1.03 Hi. This is the qmail-send program at psa.aaaaaa.com. I'm afraid I wasn't able to deliver your message to the following addresses. This is a permanent error; I've given up. Sorry it didn't work out. <[email protected]>: 82.201.133.227 does not like recipient. Remote host said: 550 #5.1.0 Address rejected. Giving up on 82.201.133.227. <[email protected]>: 64.18.7.10 does not like recipient. Remote host said: 550 No such user - psmtp Giving up on 64.18.7.10. <[email protected]>: 173.194.68.27 does not like recipient. Remote host said: 550-5.1.1 The email account that you tried to reach does not exist. Please try 550-5.1.1 double-checking the recipient's email address for typos or 550-5.1.1 unnecessary spaces. Learn more at 550 5.1.1 http://support.google.com/mail/bin/answer.py?answer=6596 w8si1903qag.18 - gsmtp Giving up on 173.194.68.27. <[email protected]>: 207.115.36.23 does not like recipient. Remote host said: 550 5.2.1 <[email protected]>... Addressee unknown, relay=[174.142.62.210] Giving up on 207.115.36.23. <[email protected]>: 207.115.37.22 does not like recipient. Remote host said: 550 5.2.1 <[email protected]>... Addressee unknown, relay=[174.142.62.210] Giving up on 207.115.37.22. <[email protected]>: 207.115.37.20 does not like recipient. Remote host said: 550 5.2.1 <[email protected]>... Addressee unknown, relay=[174.142.62.210] Giving up on 207.115.37.20. <[email protected]>: 207.115.37.23 does not like recipient. Remote host said: 550 5.2.1 <[email protected]>... Addressee unknown, relay=[174.142.62.210] Giving up on 207.115.37.23. <[email protected]>: 207.115.36.22 does not like recipient. Remote host said: 550 5.2.1 <[email protected]>... Addressee unknown, relay=[174.142.62.210] Giving up on 207.115.36.22. <[email protected]>: 74.205.16.140 does not like recipient. Remote host said: 553 sorry, that domain isn't in my list of allowed rcpthosts; no valid cert for gatewaying (#5.7.1) Giving up on 74.205.16.140. <[email protected]>: 207.115.36.20 does not like recipient. Remote host said: 550 5.2.1 <[email protected]>... Addressee unknown, relay=[174.142.62.210] Giving up on 207.115.36.20. <[email protected]>: 207.115.37.21 does not like recipient. Remote host said: 550 5.2.1 <[email protected]>... Addressee unknown, relay=[174.142.62.210] Giving up on 207.115.37.21. <[email protected]>: 192.169.41.23 failed after I sent the message. Remote host said: 554 qq Sorry, no valid recipients (#5.1.3) --- Below this line is a copy of the message. Return-Path: <[email protected]> Received: (qmail 15962 invoked from network); 1 May 2013 06:49:34 -0400 Received: from exprod6mo107.postini.com (64.18.1.18) by psa.aaaaaa.com with (DHE-RSA-AES256-SHA encrypted) SMTP; 1 May 2013 06:49:34 -0400 Received: from aaaaaa.com (exprod6lut001.postini.com [64.18.1.199]) by exprod6mo107.postini.com (Postfix) with SMTP id 47F80B8CA4 for <[email protected]>; Wed, 1 May 2013 03:49:33 -0700 (PDT) From: "Support" <[email protected]> To: [email protected] Subject: Detected Potential Junk Mail Date: Wed, 1 May 2013 03:49:33 -0700 Dear [email protected], junk mail protection service has detected suspicious email message(s) since your last visit and directed them to your Message Center. You can inspect your suspicious email at: ... UPDATE: After not seeing this problem for a while, I personally sent a message and immediately got a bounce with several bad addresses that I know I did not send to. These are addresses that are not on my system or on the server. This problem happens with both Mac and Windows clients and with messages generated from Postini and sent to users on my system. This is NOT backscatter. If it was backscatter it would not have the contents of my message in it. UPDATE #2 Here is another bounce. This one was sent by me and the bounce came back immediately. Hi. This is the qmail-send program at psa.aaaaaa.com. I'm afraid I wasn't able to deliver your message to the following addresses. This is a permanent error; I've given up. Sorry it didn't work out. <[email protected]>: 71.74.56.227 does not like recipient. Remote host said: 550 5.1.1 <[email protected]>... User unknown Giving up on 71.74.56.227. <[email protected]>: Connected to 208.34.236.3 but sender was rejected. Remote host said: 550 5.7.1 This system is configured to reject mail from 174.142.62.210 [174.142.62.210] (Host blacklisted - Found on Realtime Black List server 'bl.mailspike.net') <[email protected]>: 66.96.80.22 failed after I sent the message. Remote host said: 552 sorry, mailbox [email protected] is over quota temporarily (#5.1.1) <[email protected]>: 83.145.109.52 does not like recipient. Remote host said: 550 5.1.1 <[email protected]>: Recipient address rejected: User unknown in virtual mailbox table Giving up on 83.145.109.52. <[email protected]>: 69.49.101.234 does not like recipient. Remote host said: 550 5.7.1 <[email protected]>... H:M12 [174.142.62.210] Connection refused due to abuse. Please see http://mailspike.org/anubis/lookup.html or contact your E-mail provider. Giving up on 69.49.101.234. <[email protected]>: 212.55.154.36 does not like recipient. Remote host said: 550-The account has been suspended for inactivity 550 A conta do destinatario encontra-se suspensa por inactividade (#5.2.1) Giving up on 212.55.154.36. <[email protected]>: 199.168.90.102 failed after I sent the message. Remote host said: 552 Transaction [email protected] failed, remote said "550 No such user" (#5.1.1) <[email protected]>: 98.136.217.192 failed after I sent the message. Remote host said: 554 delivery error: dd Sorry your message to [email protected] cannot be delivered. This account has been disabled or discontinued [#102]. - mta1210.sbc.mail.gq1.yahoo.com --- Below this line is a copy of the message. Return-Path: <[email protected]> Received: (qmail 2618 invoked from network); 2 Jun 2013 22:32:51 -0400 Received: from 75-138-254-239.dhcp.jcsn.tn.charter.com (HELO ?192.168.0.66?) (75.138.254.239) by psa.aaaaaa.com with SMTP; 2 Jun 2013 22:32:48 -0400 User-Agent: Microsoft-Entourage/12.34.0.120813 Date: Sun, 02 Jun 2013 21:32:39 -0500 Subject: Refinance From: Tim Duncklee <[email protected]> To: Scott jones <[email protected]> Message-ID: <CDD16A79.67344%[email protected]> Thread-Topic: Reference Thread-Index: Ac5gAp2QmTs+LRv0SEOy7AJTX2DWzQ== Mime-version: 1.0 Content-type: multipart/mixed; boundary="B_3453053568_12034440" > This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --B_3453053568_12034440 Content-type: multipart/related; boundary="B_3453053568_11982218" --B_3453053568_11982218 Content-type: multipart/alternative; boundary="B_3453053568_12000660" --B_3453053568_12000660 Content-type: text/plain; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Scott, ... email body here ... Here are the relevant log entries: Jun 2 22:32:50 psa qmail-queue[2616]: mail: all addreses are uncheckable - need to skip scanning (by deny mode) Jun 2 22:32:50 psa qmail-queue[2616]: scan: the message(drweb.tmp.i2SY0n) sent by [email protected] to [email protected] should be passed without checks, because contains uncheckable addresses Jun 2 22:32:50 psa qmail-queue-handlers[2617]: Handlers Filter before-queue for qmail started ... Jun 2 22:32:50 psa qmail-queue-handlers[2617]: [email protected] Jun 2 22:32:50 psa qmail-queue-handlers[2617]: [email protected] Jun 2 22:32:50 psa qmail-queue-handlers[2617]: hook_dir = '/var/qmail//handlers/before-queue' Jun 2 22:32:50 psa qmail-queue-handlers[2617]: recipient[3] = '[email protected]' Jun 2 22:32:50 psa qmail-queue-handlers[2617]: handlers dir = '/var/qmail//handlers/before-queue/recipient/[email protected]' Jun 2 22:32:51 psa qmail: 1370226771.060211 starting delivery 57: msg 1540285 to remote [email protected] Jun 2 22:32:51 psa qmail: 1370226771.060402 status: local 0/10 remote 1/20 Jun 2 22:32:51 psa qmail: 1370226771.060556 new msg 4915232 Jun 2 22:32:51 psa qmail: 1370226771.060671 info msg 4915232: bytes 687899 from <[email protected]> qp 2618 uid 2020 Jun 2 22:32:51 psa qmail-remote-handlers[2619]: Handlers Filter before-remote for qmail started ... Jun 2 22:32:51 psa qmail-queue-handlers[2617]: starter: submitter[2618] exited normally Jun 2 22:32:51 psa qmail-remote-handlers[2619]: from= Jun 2 22:32:51 psa qmail-remote-handlers[2619]: [email protected] Jun 2 22:32:51 psa qmail: 1370226771.078732 starting delivery 58: msg 4915232 to remote [email protected] Jun 2 22:32:51 psa qmail: 1370226771.078825 status: local 0/10 remote 2/20 Jun 2 22:32:51 psa qmail-remote-handlers[2621]: Handlers Filter before-remote for qmail started ... Jun 2 22:32:51 psa qmail-remote-handlers[2621]: [email protected] Jun 2 22:32:51 psa qmail-remote-handlers[2621]: [email protected]

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  • Tuxedo Load Balancing

    - by Todd Little
    A question I often receive is how does Tuxedo perform load balancing.  This is often asked by customers that see an imbalance in the number of requests handled by servers offering a specific service. First of all let me say that Tuxedo really does load or request optimization instead of load balancing.  What I mean by that is that Tuxedo doesn't attempt to ensure that all servers offering a specific service get the same number of requests, but instead attempts to ensure that requests are processed in the least amount of time.   Simple round robin "load balancing" can be employed to ensure that all servers for a particular service are given the same number of requests.  But the question I ask is, "to what benefit"?  Instead Tuxedo scans the queues (which may or may not correspond to servers based upon SSSQ - Single Server Single Queue or MSSQ - Multiple Server Single Queue) to determine on which queue a request should be placed.  The scan is always performed in the same order and during the scan if a queue is empty the request is immediately placed on that queue and request routing is done.  However, should all the queues be busy, meaning that requests are currently being processed, Tuxedo chooses the queue with the least amount of "work" queued to it where work is the sum of all the requests queued weighted by their "load" value as defined in the UBBCONFIG file.  What this means is that under light loads, only the first few queues (servers) process all the requests as an empty queue is often found before reaching the end of the scan.  Thus the first few servers in the queue handle most of the requests.  While this sounds non-optimal, in fact it capitalizes on the underlying operating systems and hardware behavior to produce the best possible performance.  Round Robin scheduling would spread the requests across all the available servers and thus require all of them to be in memory, and likely not share much in the way of hardware or memory caches.  Tuxedo's system maximizes the various caches and thus optimizes overall performance.  Hopefully this makes sense and now explains why you may see a few servers handling most of the requests.  Under heavy load, meaning enough load to keep all servers that can handle a request busy, you should see a relatively equal number of requests processed.  Next post I'll try and cover how this applies to servers in a clustered (MP) environment because the load balancing there is a little more complicated. Regards,Todd LittleOracle Tuxedo Chief Architect

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  • More useful Sql Server Serivce Broker Queries

    - by ChrisD
    SELECT 'Checking Broker Service Status...' IF (select Top 1 is_broker_enabled from sys.databases where name = 'NWMESSAGE')=1     SELECT ' Broker Service IS Enabled'  -- Should return a 1. ELSE     SELECT '** Broker Service IS DISABLED ***' /* If Is_Broker_enabled returns 0, uncomment and run this code ALTER DATABASE NWMESSAGE SET SINGLE_USER WITH ROLLBACK IMMEDIATE GO Alter Database NWMESSAGE Set enable_broker GO ALTER DATABASE NWDataChannel SET MULTI_USER GO */ SELECT 'Checking For Disabled Queues....' -- ensure the queues are enabled --  0 indicates the queue is disabled. Select '** Receive Queue Disabled: '+name from sys.service_queues where is_receive_enabled = 0 --select [name], is_receive_enabled from sys.service_queues; /*If the queue is disabled, to enable it alter queue QUEUENAME with status=on; – replace QUEUENAME with the name of your queue */ -- Get General information about the queues --select * from sys.service_queues -- Get the message counts in each queue SELECT 'Checking Message Count for each Queue...' select q.name, p.rows from sys.objects as o join sys.partitions as p on p.object_id = o.object_id join sys.objects as q on o.parent_object_id = q.object_id join sys.service_queues sq on sq.name = q.name where p.index_id = 1 -- Ensure all the queue activiation sprocs are present SELECT 'Checking for Activation Stored Procedures....' SELECT  '** Missing Procedure:  '+q.name  From sys.service_queues q Where NOT Exists(Select * from sysobjects where xtype='p' and name='activation_'+q.name) and q.activation_procedure is not null DECLARE @sprocs Table (Name Varchar(2000)) Insert into @sprocs Values ('Echo') Insert into @sprocs Values ('HTTP_POST') Insert into @sprocs Values ('InitializeRecipients') Insert into @sprocs Values ('sp_EnableRecipient') Insert into @sprocs Values ('sp_ProcessReceivedMessage') Insert into @sprocs Values ('sp_SendXmlMessage') SELECT 'Checking for required stored procedures...' SELECT  '** Missing Procedure:  '+s.name  From @sprocs s Where NOT Exists(Select * from sysobjects where xtype='p' and name=s.name) GO -- Check the services Select 'Checking Recipient Message Services...' Select '** Missing Message Service:' + r.RecipientName +'MessageService' From Recipient r Where not exists (Select * from sys.services s where  s.name  COLLATE SQL_Latin1_General_CP1_CI_AS= r.RecipientName+'MessageService') DECLARE @svcs Table (Name Varchar(2000)) Insert into @svcs Values ('XmlMessageSendingService') SELECT  '** Missing Service:  '+s.name  From @svcs s Where NOT Exists(Select * from sys.services where name=s.name COLLATE SQL_Latin1_General_CP1_CI_AS) GO /*** To Test a message send Run: sp_SendXmlMessage  'TSQLTEST', 'CommerceEngine','<Root><Text>Test</Text></Root>' */ Select CAST(message_body as XML) as xml, * From XmlMessageSendingQueue /*** clean out all queues declare @handle uniqueidentifier declare conv cursor for   select conversation_handle from sys.conversation_endpoints open conv fetch next from conv into @handle while @@FETCH_STATUS = 0 Begin    END Conversation @handle with cleanup    fetch next from conv into @handle End close conv deallocate conv ***********************

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  • Offer me an ASP.NET & a SQL Server 2008 server specifications for about 2000 concurrent users, please.

    - by amkh
    We have a web application project wich will be created using ASP.NET 4.0, Entity Framework, and SQL Sever 2008 R2. To meet the needs, suppose a normal page of this application that has a query which it takes 10 miliseconds to response on a Core2 Quad @ 2.8GHz proccessor with 2x2GB of DDR3 Ram (EntityFramework overheads are considered). And we will have about 2000 concurrent user at peek times. So, what is the best recommended specifications (CPU/RAM/RAID/...) for the server which will be host this application? -- Or -- How can I calculate that?

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  • How to auto create a JMS topic/queue on JBoss in a portable and per-application way?

    - by Bozho
    It's simple: I have an MDB and an EJB that sends messages to a topic (or queue). JBoss complains that the topic is not bound to the JNDI context. I want to have the topic/queue to be automatically created at best, or at least to have a standard way to define it, per application (say, in ejb-jar/META-INF) this question and this blogpost show us how to do it in an application server specific way. This surely works, but: I want to use the @MessageDriven annotation I want the setting not to be global for the application server I want the setting to be portable

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  • Server overloaded with log messages: tty_release_dev: pts0: read/write wait queue active!

    - by Raph
    In the logs, I have this (extract from the full kernel messages logges at 06:01:14): Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.863038] BUG: unable to handle kernel NULL pointer dereference at 0000000000000015 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861081] Process telnet (pid: 20247, threadinfo ffff8800f8598000, task ffff8800024d4500) And then the server logs flooded by this message: Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861547] tty_release_dev: pts0: read/write wait queue active! In the end, 2 hours later, I had to reboot because it had become inaccessible: the load hat grown to 160%. The last command does not show anyone logged on pts0 at that time. I also don't know where this telnet process could come from.... This is an AWS instance running UBUNTU 10.04 LTS And here are the complete logs: Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.863038] BUG: unable to handle kernel NULL pointer dereference at 0000000000000015 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861007] IP: [<ffffffff81363dde>] n_tty_read+0x2ce/0x970 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861019] PGD ee13d067 PUD f8698067 PMD 0 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861025] Oops: 0000 [#1] SMP Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861028] last sysfs file: /sys/devices/xen/vbd-2208/block/sdk/removable Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861032] CPU 0 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861034] Modules linked in: ipv6 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861040] Pid: 20247, comm: telnet Not tainted 2.6.32-312-ec2 #24-Ubuntu Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861042] RIP: e030:[<ffffffff81363dde>] [<ffffffff81363dde>] n_tty_read+0x2ce/0x970 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861047] RSP: e02b:ffff8800f8599d88 EFLAGS: 00010246 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861049] RAX: 0000000000000015 RBX: ffff8800f8598000 RCX: 0000000001aed069 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861052] RDX: 0000000000000000 RSI: ffff8800f8599e67 RDI: ffff8801dd833d1c Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861054] RBP: ffff8800f8599e98 R08: ffffffff8135eb10 R09: 7fffffffffffffff Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861057] R10: 0000000000000000 R11: 0000000000000246 R12: ffff8801dd833800 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861059] R13: 0000000000000000 R14: ffff8801dd833a68 R15: ffff8801dd833d1c Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861065] FS: 00007f90121f6720(0000) GS:ffff880002c40000(0000) knlGS:0000000000000000 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861068] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861070] CR2: 0000000000000015 CR3: 0000000032a59000 CR4: 0000000000002660 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861073] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861076] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861081] Process telnet (pid: 20247, threadinfo ffff8800f8598000, task ffff8800024d4500) Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861083] Stack: Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861085] 0000000000000000 0000000001aed069 ffff8801dd8339c8 ffff8800024d4500 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861089] <0> ffff8801dd8339c0 ffff8801dd833c90 0000000001aed027 ffff8800024d4500 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861094] <0> ffff8801dd8338d8 0000000000000000 ffff8800024d4500 0000000000000000 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861099] Call Trace: Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861107] [<ffffffff81034bc0>] ? default_wake_function+0x0/0x10 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861113] [<ffffffff8135ebb6>] tty_read+0xa6/0xf0 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861118] [<ffffffff810ee7e5>] vfs_read+0xb5/0x1a0 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861122] [<ffffffff810ee91c>] sys_read+0x4c/0x80 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861127] [<ffffffff81009ba8>] system_call_fastpath+0x16/0x1b Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861131] [<ffffffff81009b40>] ? system_call+0x0/0x52 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861133] Code: 85 d2 0f 84 92 00 00 00 45 8b ac 24 5c 02 00 00 f0 45 0f b3 2e 45 19 ed 49 63 84 24 5c 02 00 00 49 8b 94 24 50 02 00 00 4c 89 ff <0f> be 1c 02 e8 a9 d3 14 00 41 8b 94 24 5c 02 00 00 41 83 ac 24 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861171] RIP [<ffffffff81363dde>] n_tty_read+0x2ce/0x970 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861175] RSP <ffff8800f8599d88> Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861171] RIP [<ffffffff81363dde>] n_tty_read+0x2ce/0x970 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861175] RSP <ffff8800f8599d88> Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861177] CR2: 0000000000000015 Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861205] ---[ end trace f10eee2057ff4f6b ]--- Apr 21 06:01:14 ip-10-49-109-107 kernel: [233185.861547] tty_release_dev: pts0: read/write wait queue active!

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  • Exchange 2010: How to retain mail in the outgoing queue for a certain amount of time before it is being sent

    - by Jeroen Landheer
    One of our clients asked us to configure Exchange 2010 to retain outgoing mail for a certain amount of time (independant of Outlook settings.) The idea is that an administrator has about 10 minutes to take a message out of a queue before it is sent out the organization. I know this can be configured in Outlook, but this is not a valiable solution for us. I'm also aware that this causes queues to fill up, this is part of the consideration. Is there a way in Exchange 2010 to configure this?

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  • Why does Exim puts emails on hold if there are frozen messages in the queue?

    - by user51932
    I've a CentOS with CPanel server working as a SMTP server, which currently uses 20 different hostnames and IP addresses to deliver email for an email newsletter service. However, it's extremely slow in sending emails. It's sending like 10 emails per minute, which I check by running the "exim -bpc" command. What could be affecting this? One thing I'm supposing, is that there are frozen messages in the queue, which are slowing down the sending until they're sent out, and are putting new messages on hold. What are the most common reasons a message can get frozen? Also, would it be more efficient to use 20 different small VPSs to send out email rather than use one large VPS with the 20 different hostnames and IPs in it?

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  • Why does Exim puts emails on hold if there are frozen messages in the queue?

    - by user51932
    Hi, I've a CentOS with CPanel server working as a SMTP server, which currently uses 20 different hostnames and IP addresses to deliver email for an email newsletter service. However, it's extremely slow in sending emails. It's sending like 10 emails per minute, which I check by running the "exim -bpc" command. What could be affecting this? One thing I'm supposing, is that there are frozen messages in the queue, which are slowing down the sending until they're sent out, and are putting new messages on hold. What are the most common reasons a message can get frozen? Also, would it be more efficient to use 20 different small VPSs to send out email rather than use one large VPS with the 20 different hostnames and IPs in it?

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