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  • sticky bit on NFS file system

    - by Kris_R
    I have a system where to the main server (homes, nfs, ntp, queue...) can log-in only root – all the other users use front-end host with NFS-mounted home directories (RW) and all other software directories (read-only). My problem is, that time to time, if root or normal user with sudo makes some administrative works on front-end some homes of normal users getting sticky bits (drwsr-sr-x). If it happens usually the user can't log-in (as long as permission for his home are not changed to drwxr-xr-x). The last time I saw it after compiling some new software (normal user configure;make) and installation from the same directory as root (su and make install or direct as normal user sudo make install). Can somebody explain me why it happens and what should I do to get rid of this problem? p.s. I'm using CentOS 5.7

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  • how can I estimate the conversion speed (fps) of a video based on CPU power? [closed]

    - by Ahoura Ghotbi
    Atm I am running a video sharing website and I am converting alot of videos. the queue is getting a bit too long (400 videos). I am planning on purchasing a new server and I was wondering if there anyway I can estimate the fps while converting 10 videos at the same time? Regards EXTRA INFO I am using MP4Box (which uses ffmpeg) to handle the encoding etc. Its encoding at 23 CRF, audio bitrate of 96 and audio sampling rate of 44100. The server will have the following processor : Dual Opteron 6272 (2 x 16 cores, 32 cores total) + 128GB RAM.

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  • How to enable Postfix filter on OS X server (Lion) without getting overwritten?

    - by mjbraun
    I have a Postfix after-queue content filter that works fine on stock Ubuntu Postfix install. However, on a OS X Lion Server I'm testing out, I see this "auto-generated" language in the master.cf file: # ==== Begin auto-generated section ======================================== # This section of the master.cf file is auto-generated by the Server Admin # Mail backend plugin whenever mails settings are modified. smtp inet n - n - 1 postscreen smtpd pass - - n - - smtpd -o receive_override_options=no_address_mappings The problem is, to enable the filter the same area of the master.cf file has to be changed to have an entry like this: smtp inet n - - - - smtpd -o content_filter=mytest_filter:dummy So, it looks like the line would be blown away every I make a change in Server Admin. Is there a better place for me to put the call to the filter such that it's persistent? I appreciate any assistance and/or guidance!

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  • Use backups if unavailable (not just down)

    - by PriceChild
    Using haproxy, I want: A pool of 'main' servers and 'backup' servers, though they don't necessarily have to be in separate pools. Each backend has a low 'maxconn' (in this case 1) Clients should not wait in a queue. If there are no immediately available servers in the 'main' pool they should be shunted to the 'backup' pool without delay. Right now I have one backend, 'main' servers have an absurdly high weighting and it 'works'. acl use_backend + connslots is along the right lines but without the patch in my own answer it isn't perfect. Bonus points for not requiring a modified haproxy binary.

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  • Primefaces: java.lang.ClassCastException: java.util.HashMap cannot be cast to ClassObject

    - by razegarra
    I have a problem with p:dataTable in Primefaces, I can not find the error. Class UsuarioAsig: public class UsuarioAsig { private BigDecimal codigopersona; private String nombre; private String paterno; private String materno; private String login; private String observacion; private String tipocontrol; private String externo; private String habilitado; private String nombreperfil; private BigDecimal codigousuario; ...get and set...} Class UsuarioAsigListaDataModel: public class UsuarioAsigListaDataModel extends ListDataModel<UsuarioAsig> implements SelectableDataModel<UsuarioAsig> { public UsuarioAsigListaDataModel(){} public UsuarioAsigListaDataModel(List<UsuarioAsig> data){super(data);} @Override public UsuarioAsig getRowData(String rowKey) { @SuppressWarnings("unchecked") List<UsuarioAsig> listaUsuarioAsigLectura = (List<UsuarioAsig>) getWrappedData(); for (UsuarioAsig usuarioAsig : listaUsuarioAsigLectura) { if (usuarioAsig.getCodigopersona().equals(rowKey)) { return usuarioAsig; } } return null; } @Override public Object getRowKey(UsuarioAsig usuarioAsig) { return usuarioAsig.getCodigopersona(); }} Controller UsuarioAsigController: @Controller("usuarioAsigController") @Scope(value = "session") public class UsuarioAsigController { private List<UsuarioAsig> listaUsuarioAsig; private HashMap<String, Object> selUsuarioAsig; private UsuarioAsigListaDataModel mediumUsuarioAsigModel; @Autowired UsuarioService usuarioService; ... public List<UsuarioAsig> getListaUsuarioAsig() { listaUsuarioAsig = usuarioService.selectAsig(); return listaUsuarioAsig; } public void setListaUsuarioAsig(List<UsuarioAsig> listaUsuarioAsig) { this.listaUsuarioAsig = listaUsuarioAsig; } public void setMediumUsuarioAsigModel(UsuarioAsigListaDataModel mediumUsuarioAsigModel) { this.mediumUsuarioAsigModel = mediumUsuarioAsigModel; } public UsuarioAsigListaDataModel getMediumUsuarioAsigModel() { listaUsuarioAsig = usuarioService.selectAsig(); mediumUsuarioAsigModel = new UsuarioAsigListaDataModel(listaUsuarioAsig); return mediumUsuarioAsigModel; } public void onRowSelect(SelectEvent event) { FacesMessage msg = new FacesMessage("Usuario seleccionado", ((UsuarioAsig) event.getObject()).getNombre()); FacesContext.getCurrentInstance().addMessage(null, msg); } } the error is generated when you click on one of the lines of datatable: asiginst.xhtml: <h:form id="form"> <p:growl id="msgs" showDetail="true" /> <p:dataTable id="usuarioAsigListaDataModel" var="usuarioAsig" value="#{usuarioAsigController.mediumUsuarioAsigModel}" rowKey="#{usuarioAsig.codigopersona}" selection="#{usuarioAsigController.selUsuarioAsig}" selectionMode="single" paginator="true" rows="10"> <p:ajax event="rowSelect" listener="#{usuarioAsigController.onRowSelect}" update=":form:msgs" /> <p:column headerText="Código" style="width:10%">#{usuarioAsig.codigopersona}</p:column> <p:column headerText="Nombre" style="width:32%">#{usuarioAsig.nombre}</p:column> <p:column headerText="Apellidos" style="width:32%">#{usuarioAsig.paterno} #{usuarioasig.materno}</p:column> <p:column headerText="Tipo Control" style="width:20%">#{usuarioAsig.tipocontrol}</p:column> <p:column headerText="Habilitado" style="width:6%">#{usuarioAsig.habilitado}</p:column> </p:dataTable> </h:form> THE ERROR IS GENERATED: WARNING: asiginst.xhtml @51,103 listener="#{usuarioAsigController.onRowSelect}": java.lang.ClassCastException: java.util.HashMap cannot be cast to com.datos.entidades.qry.UsuarioAsig javax.el.ELException: asiginst.xhtml @51,103 listener="#{usuarioAsigController.onRowSelect}": java.lang.ClassCastException: java.util.HashMap cannot be cast to com.datos.entidades.qry.UsuarioAsig at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:111) at org.primefaces.behavior.ajax.AjaxBehaviorListenerImpl.processArgListener(AjaxBehaviorListenerImpl.java:69) at org.primefaces.behavior.ajax.AjaxBehaviorListenerImpl.processAjaxBehavior(AjaxBehaviorListenerImpl.java:56) at org.primefaces.event.SelectEvent.processListener(SelectEvent.java:40) at javax.faces.component.behavior.BehaviorBase.broadcast(BehaviorBase.java:102) at javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:760) at javax.faces.component.UIData.broadcast(UIData.java:1071) at javax.faces.component.UIData.broadcast(UIData.java:1093) at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794) at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259) at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81) at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) at javax.faces.webapp.FacesServlet.service(FacesServlet.java:409) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:309) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722) Caused by: java.lang.ClassCastException: java.util.HashMap cannot be cast to com.datos.entidades.qry.UsuarioAsig at com.controller.UsuarioAsigController.onRowSelect(UsuarioAsigController.java:217) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at org.apache.el.parser.AstValue.invoke(AstValue.java:264) at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:278) at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105) ... 29 more

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  • IIS 6.0 Server Too Busy HTTP 503 Connection_Dropped DefaultAppPool

    - by Shiraz Bhaiji
    We have a site which is running on a windows 2003 cluster with 2 64bit machines. The site needs to be able to cope with over 20,000 concurrent users One of the things that the site does is to allow the download of a 2MB file (which is cached in memory). We have low CPU and memory usage. We also have surplus bandwidth. It appears that we are running out of connections due the time it takes the user to download the file (some users have slow internet connections). In the IIS log we get HTTP 503 errors. In the HTTPErr log we get mainly Connection_Dropped DefaultAppPool with some Timer_EntityBody DefaultAppPool. Question is: How can we configure IIS to allow more connections? Or is there something that I am missing here? Thanks Shiraz

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  • Delphi - WndProc() in thread never called

    - by Robert Oschler
    I had code that worked fine when running in the context of the main VCL thread. This code allocated it's own WndProc() in order to handle SendMessage() calls. I am now trying to move it to a background thread because I am concerned that the SendMessage() traffic is affecting the main VCL thread adversely. So I created a worker thread with the sole purpose of allocating the WndProc() in its thread Execute() method to ensure that the WndProc() existed in the thread's execution context. The WndProc() handles the SendMessage() calls as they come in. The problem is that the worker thread's WndProc() method is never triggered. Note, doExecute() is part of a template method that is called by my TThreadExtended class which is a descendant of Delphi's TThread. TThreadExtended implements the thread Execute() method and calls doExecute() in a loop. I triple-checked and doExecute() is being called repeatedly. Also note that I call PeekMessage() right after I create the WndProc() in order to make sure that Windows creates a message queue for the thread. However something I am doing is wrong since the WndProc() method is never triggered. Here's the code below: // ========= BEGIN: CLASS - TWorkerThread ======================== constructor TWorkerThread.Create; begin FWndProcHandle := 0; inherited Create(false); end; // --------------------------------------------------------------- // This call is the thread's Execute() method. procedure TWorkerThread.doExecute; var Msg: TMsg; begin // Create the WndProc() in our thread's context. if FWndProcHandle = 0 then begin FWndProcHandle := AllocateHWND(WndProc); // Call PeekMessage() to make sure we have a window queue. PeekMessage(Msg, FWndProcHandle, 0, 0, PM_NOREMOVE); end; if Self.Terminated then begin // Get rid of the WndProc(). myDeallocateHWnd(FWndProcHandle); end; // Sleep a bit to avoid hogging the CPU. Sleep(5); end; // --------------------------------------------------------------- procedure TWorkerThread.WndProc(Var Msg: TMessage); begin // THIS CODE IS NEVER CALLED. try if Msg.Msg = WM_COPYDATA then begin // Is LParam assigned? if (Msg.LParam > 0) then begin // Yes. Treat it as a copy data structure. with PCopyDataStruct(Msg.LParam)^ do begin ... // Here is where I do my work. end; end; // if Assigned(Msg.LParam) then end; // if Msg.Msg = WM_COPYDATA then finally Msg.Result := 1; end; // try() end; // --------------------------------------------------------------- procedure TWorkerThread.myDeallocateHWnd(Wnd: HWND); var Instance: Pointer; begin Instance := Pointer(GetWindowLong(Wnd, GWL_WNDPROC)); if Instance <> @DefWindowProc then begin // Restore the default windows procedure before freeing memory. SetWindowLong(Wnd, GWL_WNDPROC, Longint(@DefWindowProc)); FreeObjectInstance(Instance); end; DestroyWindow(Wnd); end; // --------------------------------------------------------------- // ========= END : CLASS - TWorkerThread ======================== Thanks, Robert

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  • ASP.NET 4 - IIS 7 - Request timed out - Request timed out

    - by sharru
    My website is running on Asp.net v4 , IIS 7 , Windows server 2008. My cpu is running on 20-30% and the site is responding quickly. Every 2-5 mins i'm receiving the following error: Event code: 3001 Event message: The request has been aborted. Exception type: HttpException Exception message: Request timed out. , Request information: Request URL: http://www.xxxx.com/Services/AxRefresh.asmx/AxUpdate Request path: /Services/AxRefresh.asmx/AxUpdate User host address: 84.110.251.198 User: Is authenticated: False Authentication Type: Thread account name: NT AUTHORITY\NETWORK SERVICE i read that the error is related to the maximum concurrent requests limit http://support.microsoft.com/kb/821268 but then i found out that on IIS 7 this limitation is changed and not relevant. http://msdn.microsoft.com/en-us/library/dd560842(VS.100).aspx Any other ideas what can be the problem or where to start looking ? Thx!

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  • C++ Winsock non-blocking/async UDP socket

    - by Ragnagard
    Hi all! I'm developping a little data processor in c++ over UDP sockets, and have a thread (just one, and apart the sockets) that process the info received from them. My problem happens when i need to receive info from multiple clients in the socket at the same time. How could i do something like: Socket foo; /* init socket vars and attribs */ while (serving){ thread_processing(foo_info); } for multiple clients (many concurrent access) in c++? I'm using winsocks atm on win32, but just get standard blocking udp sockets working. No gui, it's a console app. I'll appreciate so much an example or pointer to one ;). Thanks in advance.

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  • Writing data over RxTx using usbserial?

    - by Jeach
    I'm using the RxTx library over usbserial on a Linux distro. The RxTx lib seems to behave quite differently (in a bad way) than how it works over serial. One of my biggest problems is that the RxTx SerialPortEvent.OUTPUT_BUFFER_EMPTY does not work on linux over usbserial. How do I know when I should write to the stream? Any indicators I might have missed? So far my experience with writing and reading concurrently have not been great. Does anyone know if I should lock the DATA_AVAILABLE handler from being invoked while I'm writing on the stream? Or RxTx accepts concurrent read/writes? Thanks in advance

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  • Java Concurrency: CAS vs Locking

    - by Hugo Walker
    Im currently reading the Book Java Concurrency in Practice. In the Chapter 15 they are speaking about the Nonblocking algorithms and the compare-and-swap (CAS) Method. It is written that the CAS perform much better than the Locking Methods. I want to ask the people which already worked with both of this concepts and would like to hear when you are preferring which of these concept? Is it really so much faster? Personally for me the usage of Locks is much clearer and easier to understand and maybe even better to maintain. (Please correct me if I am wrong). Should we really focus creating our concurrent code related on CAS than Locks to get a better performance boost or is sustainability a higher thing? I know there is maybe not a strict rule, when to use what. But I just would like to hear some opinions, experiences with the new concept of CAS.

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  • .NET or Windows Synchronization Primitives Performance Specifications

    - by ovanes
    Hello *, I am currently writing a scientific article, where I need to be very exact with citation. Can someone point me to either MSDN, MSDN article, some published article source or a book, where I can find performance comparison of Windows or .NET Synchronization primitives. I know that these are in the descending performance order: Interlocked API, Critical Section, .NET lock-statement, Monitor, Mutex, EventWaitHandle, Semaphore. Many Thanks, Ovanes P.S. I found a great book: Concurrent Programming on Windows by Joe Duffy. This book is written by one of the head concurrency developers for .NET Framework and is simply brilliant with lots of explanations, how things work or were implemented.

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  • How do continuously update data to an asp page?

    - by Lori
    Hi, I have an asp page based on a very simple database. It references a single table of probably 30 records and maybe 12 data fields and everything works great as I am only uploading a new database every week or so. I have a special circumstance where I would like upload new data to the database and display automatically on the page every 20 to 30 seconds without the user having to refresh their screen. I would expect up to 1000 concurrent users accessing the data. I have been manually uploading the database via ftp, which will obviously not work on this timeline and would also run the risk of error pages as the database is being replaced. So, can anyone point me the right direction to setup this scenario? Other details that might be helpful: The database is an Access database (but I could change to another format if needed) Running on Windows platform hosted by an ISP, not my own server Thanks in advance for any help on this! Lori

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  • Where to get apache poi port for .net

    - by Nassign
    I would like to know if there is a website where I could download the Apache POI ported for .net? I already found this link in the web http://www.apache.org/~avik/dist/poi-2.5.1-dev-20040708.dll But the version of apache poi now is 3.6, I was wondering if there is a latest version out there? Does the apache foundation support such porting? I already tried to search the apache website too with no avail. As for using Microsoft library, the excel interopt is not that good for concurrent processing like a web backend. If I use the DocumentFormat.OpenXML library, I have a limitation of creating office 2007 document only.

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  • Freezes (not crashes) with GCD, blocks and Core Data

    - by Lukasz
    I have recently rewritten my Core Data driven database controller to use Grand Central Dispatch to manage fetching and importing in the background. Controller can operate on 2 NSManagedContext's: NSManagedObjectContext *mainMoc instance variable for main thread. this contexts is used only by quick access for UI by main thread or by dipatch_get_main_queue() global queue. NSManagedObjectContext *bgMoc for background tasks (importing and fetching data for NSFetchedresultsController for tables). This background tasks are fired ONLY by user defined queue: dispatch_queue_t bgQueue (instance variable in database controller object). Fetching data for tables is done in background to not block user UI when bigger or more complicated predicates are performed. Example fetching code for NSFetchedResultsController in my table view controllers: -(void)fetchData{ dispatch_async([CDdb db].bgQueue, ^{ NSError *error = nil; [[self.fetchedResultsController fetchRequest] setPredicate:self.predicate]; if (self.fetchedResultsController && ![self.fetchedResultsController performFetch:&error]) { NSSLog(@"Unresolved error in fetchData %@", error); } if (!initial_fetch_attampted)initial_fetch_attampted = YES; fetching = NO; dispatch_async(dispatch_get_main_queue(), ^{ [self.table reloadData]; [self.table scrollRectToVisible:CGRectMake(0, 0, 100, 20) animated:YES]; }); }); } // end of fetchData function bgMoc merges with mainMoc on save using NSManagedObjectContextDidSaveNotification: - (void)bgMocDidSave:(NSNotification *)saveNotification { // CDdb - bgMoc didsave - merging changes with main mainMoc dispatch_async(dispatch_get_main_queue(), ^{ [self.mainMoc mergeChangesFromContextDidSaveNotification:saveNotification]; // Extra notification for some other, potentially interested clients [[NSNotificationCenter defaultCenter] postNotificationName:DATABASE_SAVED_WITH_CHANGES object:saveNotification]; }); } - (void)mainMocDidSave:(NSNotification *)saveNotification { // CDdb - main mainMoc didSave - merging changes with bgMoc dispatch_async(self.bgQueue, ^{ [self.bgMoc mergeChangesFromContextDidSaveNotification:saveNotification]; }); } NSfetchedResultsController delegate has only one method implemented (for simplicity): - (void)controllerDidChangeContent:(NSFetchedResultsController *)controller { dispatch_async(dispatch_get_main_queue(), ^{ [self fetchData]; }); } This way I am trying to follow Apple recommendation for Core Data: 1 NSManagedObjectContext per thread. I know this pattern is not completely clean for at last 2 reasons: bgQueue not necessarily fires the same thread after suspension but since it is serial, it should not matter much (there is never 2 threads trying access bgMoc NSManagedObjectContext dedicated to it). Sometimes table view data source methods will ask NSFetchedResultsController for info from bgMoc (since fetch is done on bgQueue) like sections count, fetched objects in section count, etc.... Event with this flaws this approach works pretty well of the 95% of application running time until ... AND HERE GOES MY QUESTION: Sometimes, very randomly application freezes but not crashes. It does not response on any touch and the only way to get it back to live is to restart it completely (switching back to and from background does not help). No exception is thrown and nothing is printed to the console (I have Breakpoints set for all exception in Xcode). I have tried to debug it using Instruments (time profiles especially) to see if there is something hard going on on main thread but nothing is showing up. I am aware that GCD and Core Data are the main suspects here, but I have no idea how to track / debug this. Let me point out, that this also happens when I dispatch all the tasks to the queues asynchronously only (using dispatch_async everywhere). This makes me think it is not just standard deadlock. Is there any possibility or hints of how could I get more info what is going on? Some extra debug flags, Instruments magical tricks or build setting etc... Any suggestions on what could be the cause are very much appreciated as well as (or) pointers to how to implement background fetching for NSFetchedResultsController and background importing in better way.

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  • Jetty 6 - QueuedThreadPool versus ThreadPool

    - by Walter White
    Hi all, I am using Jetty 6 and was wondering when the QueuedThreadPool should be used over the ThreadPool? By default, Jetty 6 comes configured with the QueuedThreadPool. My server has Java 6 installed so I was thinking that I should use the ThreadPool: <New class="org.mortbay.thread.QueuedThreadPool"> <Set name="minThreads">10</Set> <Set name="maxThreads">200</Set> <Set name="lowThreads">20</Set> <Set name="SpawnOrShrinkAt">2</Set> </New> <New class="org.mortbay.thread.concurrent.ThreadPool"> <Set name="corePoolSize">50</Set> <Set name="maximumPoolSize">50</Set> </New> Thanks, Walter

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  • StreamReader ReadToEnd() after HttpWebRequest EndGetResponse() - most scalable?

    - by frankadelic
    I am calling a RESTful web service in the back-end of some ASP.NET pages. I am using ASP.NET asynchronous pages, so under the hood I am using the methods: HttpWebRequest BeginGetResponse() and HttpWebRequest EndGetResponse() The response string in my case is always a JSON string. I use the following code to read the entire string: using (StreamReader sr = new StreamReader(myHttpWebResponse.GetResponseStream())) { myObject.JSONData = sr.ReadToEnd(); } Is this method OK in terms of scalability? I have seen other code samples that instead retrieve the response data in blocks using Read(). My primary goal is scalability, so this back-end call can be made across many concurrent page hits. Thanks, Frank

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  • What is node.js?

    - by Jeffrey
    I don't fully get what node.js is all about. Maybe it's because I am mainly a web based business app developer. Can someone please explain what it is and the use of it? Thanks. My understanding so far is that: The programming model is event driven, especially the way it handles IO. It uses javascript and the parser is V8. It can be easily used to create concurrent server apps. Are my understandings correct? If yes, then what are the benefits of evented IO, is it just more for the concurrency stuffs? Also is the direction of node.js to become a framework like, javascript based (v8 based) programming model?

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  • How to implement an offline reader writer lock

    - by Peter Morris
    Some context for the question All objects in this question are persistent. All requests will be from a Silverlight client talking to an app server via a binary protocol (Hessian) and not WCF. Each user will have a session key (not an ASP.NET session) which will be a string, integer, or GUID (undecided so far). Some objects might take a long time to edit (30 or more minutes) so we have decided to use pessimistic offline locking. Pessimistic because having to reconcile conflicts would be far too annoying for users, offline because the client is not permanently connected to the server. Rather than storing session/object locking information in the object itself I have decided that any aggregate root that may have its instances locked should implement an interface ILockable public interface ILockable { Guid LockID { get; } } This LockID will be the identity of a "Lock" object which holds the information of which session is locking it. Now, if this were simple pessimistic locking I'd be able to achieve this very simply (using an incrementing version number on Lock to identify update conflicts), but what I actually need is ReaderWriter pessimistic offline locking. The reason is that some parts of the application will perform actions that read these complex structures. These include things like Reading a single structure to clone it. Reading multiple structures in order to create a binary file to "publish" the data to an external source. Read locks will be held for a very short period of time, typically less than a second, although in some circumstances they could be held for about 5 seconds at a guess. Write locks will mostly be held for a long time as they are mostly held by humans. There is a high probability of two users trying to edit the same aggregate at the same time, and a high probability of many users needing to temporarily read-lock at the same time too. I'm looking for suggestions as to how I might implement this. One additional point to make is that if I want to place a write lock and there are some read locks, I would like to "queue" the write lock so that no new read locks are placed. If the read locks are removed withing X seconds then the write lock is obtained, if not then the write lock backs off; no new read-locks would be placed while a write lock is queued. So far I have this idea The Lock object will have a version number (int) so I can detect multi-update conflicts, reload, try again. It will have a string[] for read locks A string to hold the session ID that has a write lock A string to hold the queued write lock Possibly a recursion counter to allow the same session to lock multiple times (for both read and write locks), but not sure about this yet. Rules: Can't place a read lock if there is a write lock or queued write lock. Can't place a write lock if there is a write lock or queued write lock. If there are no locks at all then a write lock may be placed. If there are read locks then a write lock will be queued instead of a full write lock placed. (If after X time the read locks are not gone the lock backs off, otherwise it is upgraded). Can't queue a write lock for a session that has a read lock. Can anyone see any problems? Suggest alternatives? Anything? I'd appreciate feedback before deciding on what approach to take.

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  • 640 enterprise library caching threads - how?

    - by JohnW
    We have an application that is undergoing performance testing. Today, I decided to take a dump of w3wp & load it in windbg to see what is going on underneath the covers. Imagine my surprise when I ran !threads and saw that there are 640 background threads, almost all of which seem to say the following: OS Thread Id: 0x1c38 (651) Child-SP RetAddr Call Site 0000000023a9d290 000007ff002320e2 Microsoft.Practices.EnterpriseLibrary.Caching.ProducerConsumerQueue.WaitUntilInterrupted() 0000000023a9d2d0 000007ff00231f7e Microsoft.Practices.EnterpriseLibrary.Caching.ProducerConsumerQueue.Dequeue() 0000000023a9d330 000007fef727c978 Microsoft.Practices.EnterpriseLibrary.Caching.BackgroundScheduler.QueueReader() 0000000023a9d380 000007fef9001552 System.Threading.ExecutionContext.runTryCode(System.Object) 0000000023a9dc30 000007fef72f95fd System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object) 0000000023a9dc80 000007fef9001552 System.Threading.ThreadHelper.ThreadStart() If i had to give a guess, I'm thinkign that one of these threads are getting spawned for each run of our app - we have 2 app servers, 20 concurrent users, and ran the test approximately 30 times...it's in the neighborhood. Is this 'expected behavior', or perhaps have we implemented something improperly? The test ran hours ago, so i would have expected any timeouts to have occurred already.

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  • Providing dynamic data to webpage

    - by Marius
    Hi, I have a web page that displays dynamic data which changes every 2 seconds. Data is selected from various data sources including Oracle. Currently, the page reloads every 10 seconds and runs a PHP script which retrieves the data and displays the page. I have other pages that gives a different view on the same data. This means the same query is run again for them as well. If I have 4 of these pages with 10 concurrent users each, suddenly the data retrieval happens 40 times every 10 seconds, obviously not ideal. I have some ideas on how to improve this situation, but I thought I would ask from some ideas from other experts that might have come across a similar situation. I'm not bound to PHP, and my server is on a Linux platform. Regards Marius

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  • Providing dynamic data to webpage

    - by Marius
    Hi, I have a web page that displays dynamic data which changes every 2 seconds. Data is selected from various data sources including Oracle. Currently, the page reloads every 10 seconds and runs a PHP script which retrieves the data and displays the page. I have other pages that gives a different view on the same data. This means the same query is run again for them as well. If I have 4 of these pages with 10 concurrent users each, suddenly the data retrieval happens 40 times every 10 seconds, obviously not ideal. I have some ideas on how to improve this situation, but I thought I would ask from some ideas from other experts that might have come across a similar situation. I'm not bound to PHP, and my server is on a Linux platform. Regards Marius

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  • Best practices for managing limited client licenses/login

    - by MicSim
    I have a multi-user software solution (containing different applications, i.e. EXEs) that should allow only a limited number of concurrent users. It's designed to run in an intranet. I dont have a really good, satisfactory solution to the problem of counting the client licenses yet. The key requirements are: Multiple instances (starts) of the same application (= process) should count as only one client licence Starting different applications of the software solution should also count as only one (the same) client licence Application crash should not lead to orphaned used licences The above should work also for Terminal Server environments (all clients same IP, but different install folders) I'm looking for estabilished patterns, solutions, tips for managing used client licenses. Specific hints for the above sitaution are also welcome.

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  • How to recover gracefully from a C# udp socket exception

    - by Gearoid Murphy
    Context: I'm porting a linux perl app to C#, the server listens on a udp port and maintains multiple concurrent dialogs with remote clients via a single udp socket. During testing, I send out high volumes of packets to the udp server, randomly restarting the clients to observe the server registering the new connections. The problem is this: when I kill a udp client, there may still be data on the server destined for that client. When the server tries to send this data, it gets an icmp "no service available" message back and consequently an exception occurs on the socket. I cannot reuse this socket, when I try to associate a C# async handler with the socket, it complains about the exception, so I have to close and reopen the udp socket on the server port. Is this the only way around this problem?, surely there's some way of "fixing" the udp socket, as technically, UDP sockets shouldn't be aware of the status of a remote socket? Any help or pointers would be much appreciated. Thanks.

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  • WCF Transaction Scope SQL insert table lock

    - by lihnid
    Hi All, I have two services talking to two different Data-stores (i.e SQL). I am using transactionscope: eg: using(TransactionScope scope = new TransactionScope()) { service1.InsertUser(user);//Insert to SQL Service 1 table User service2.SavePayment(payment);//Save payment SQL Service 2 table payment scope.Complete(); } Service1 is locking the table (User) until the transaction is completed making subsequent transactions with that table sequential. Is there a way to overcome the lock, so can have more than one concurrent calls to the SQL service1 table while the above code is executing? I would appreciate any input. Thanks in Advance. Lihnid

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