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  • Determine which process (b)locks a file, programmatically (under Windows >= XP)

    - by fred-hh
    How to programmatically determine from a process P, which other process P' has a lock on a file, that prevents P from recreating that file ? I know there are tools to do that, but how do they achieve that ? (Context: a batch program that runs overnight fails because of a locked file. Running an admin tool the next day may be too late to get useful information. So it would be nice if the batch program itself was able to determine the culprit.) EDIT: Added complexity: the file resides on a DFS and P' might not run on the same machine as P (but maybe does). But a solution that works locally would be a good beginning.

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  • Javascript and rendering pauses and stays paused on scroll in the android browser

    - by user357303
    Hi. I've found some wierd behaviour related to scrolling and rendering and javascript. How to make it happen: On any webpage that is long enough to scroll on. Start to scroll pretty fast (fling the page). then release the touch. No while the page is still scrolling because of the momentum. Tap the screen to stop the scroll. This make the browser enter a wierd mode. On the nexus one it behaves like this: The updating of what's shown on the screen stops, you can still click on links and the go to where they are supposed to but what's shown on the screen stays the same. If you then scroll the screen a bit the update of the screen kicks in again and what you you where suppsed to see all the time is shown. On all phones with HTC Sense I've tried (Hero, Desire, Legend) this happens: The updating of the screen is stopped just like on the nexus one, but also the execution of any javascript is stopped. If you click on a link that takes you to another page however things return to normal again. The way I tested this was I created a page like this: http://pastebin.ca/1881620 The changeColor function simply changed the background color of 'container' to a few different colors. So before the error what happens is that when you click any link the color changes. after the error this happens: Nexus one: when you click on the links nothing happens (except the "orange link selected rounded corner box thing" is shown as if the link is clicked). Then when you scroll abit. You can see the color has changed (and equal amount of times to the number of times I clicked the link). On Sense: The links take me to google.com Has anyone else noticed this problem? Is there anyway to work around it? Thanks.

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  • prevent race condition without using locks C++

    - by Hristo
    How do I prevent a race condition with locking or using mutexes/semaphors in C++? I'm dealing with a nested for loop in which I will be setting a value in an array: for (int i = 0; i < m; ++i) for (int j = 0; j < n; ++j) for (int k = 0; k < o; ++k) array[k] += foo(...); More or less, I want to deal with this so that I can ensure different threads running at the same time don't write to array[k] at the same time. Any suggestions on how to approach this? Thanks, Hristo

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  • Using sigprocmask to implement locks

    - by EpsilonVector
    I'm implementing user threads in Linux kernel 2.4, and I'm using ualarm to invoke context switches between the threads. We have a requirement that our thread library's functions should be uninterruptable, so I looked into blocking signals and learned that using sigprocmask is the standard way to do this. However, it looks like I need to do quite a lot to implement this: sigset_t new_set, old_set; sigemptyset(&new_set); sigaddset(&new_set, SIGALRM); sigprocmask(SIG_BLOCK, &new_set, &old_set); This blocks SIGALARM but it does this with 3 function invocations! A lot can happen in the time it takes for these functions to run, including the signal being sent. The best idea I had to mitigate this was temporarily disabling ualarm, like this: sigset_t new_set, old_set; time=ualarm(0,0); sigemptyset(&new_set); sigaddset(&new_set, SIGALRM); sigprocmask(SIG_BLOCK, &new_set, &old_set); ualarm(time, 0); Which is fine except that this feels verbose. Isn't there a better way to do this?

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  • DOM Storage and locks

    - by user535759
    Since DOM storage and its equivalencies persist in between tabs and windows, I've thought about using it for message passing. The problem is that fetch and store are different operations, and therefore not atomic. I have models that rely on UUID generation, conflict resolutions, and beaconing to do the small subset of what I need to do, but my real question is this: Since the local storage is a shared memory resource, what are the locking mechanisms available for mutual access?

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  • MySQL Locks: order of unblocked threads

    - by teehoo
    I have a MySQL ISAM table being accessed my multiple php instances. Right now I'm using a WRITE lock to serialize access to this table. My question is how do I ensure that the PHP instances get served on a First-Come-First-Serve basis? Or is this the default behaviour? The official MySQL documentation doesn't mention anything about the blocked thread order for threads of the same lock type (ie multiple threads attempting a WRITE LOCK). It only mentions that a WRITER will jump to the front of the waiting queue if READERS are waiting.

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  • db2 jdbc driver does not release table locks

    - by as
    situation: We have a web service running on tomcat accessing DB2 database on AS400, we are using JTOPEN drivers for JNDI connections handled by tomcat. For handling transactions and access to database we are using Spring. For each select system takes JDBC connection from JNDI (i.e. from connection pool), does selection, and in the end it closes ResultSet, Statement and releases Connection in that order. That passes fine, shared lock on table dissappears. When we want to do update the same way as we did with select (exception on ResultSet object, we don't have one in such situation), after releasing Connection to JNDI lock on table stays. If we put maxIdle=0 for number of connections in JNDI configuration, this problem disappears, but this degrades performances, we have cca 100 users online on that service, we need few connections to be alive in pool. What do you suggest?

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  • How to use locks/synchronization here

    - by MasterGberry
    I have this code block here and i need to make sure the rankedPlayersWaitingForMatch is synchronized between threads properly. I was going to use synchronize but that i don't think will work here because of the variable being used in the if statement. I read online about final Lock lock = new ReentrantLock(); but I am a bit confused on how to use it in this case properly with the try/finally block. Can I get a quick example? Thanks // start synchronization if (rankedPlayersWaitingForMatch.get(rankedType).size() >= 2) { Player player1 = rankedPlayersWaitingForMatch.get(rankedType).remove(); Player player2 = rankedPlayersWaitingForMatch.get(rankedType).remove(); // end synchronization // ... I don't want this all to be synchronized, just after the first 2 remove() } else { // end synchronization // ... }

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  • optimistic and pessimistic locks

    - by billmce
    Working on my first php/Codeigniter project and I’ve scoured the ‘net for information on locking access to editing data and haven’t found very much information. I expect it to be a fairly regular occurrence for 2 users to attempt to edit the same form simultaneously. My experience (in the stateful world of BBx, filePro, and other RAD apps) is that the data being edited is locked using a pessimistic lock—one user has access to the edit form at the time. The second user basically has to wait for the first to finish. I understand this can be done using Ajax sending XMLHttpRequests to maintain a ‘lock’ database. The php world, lacking state, seems to prefer optimistic locking. If I understand it correctly it works like this: both users get to access the data and they each record a ‘before changes’ version of the data. Before saving their changes, the data is once again retrieved and compared the ‘before changes’ version. If the two versions are identical then the users changes are written. If they are different; the user is shown what has changed since he/she started editing and some mechanism is added to resolve the differences—or the user is shown a ‘Sorry, try again’ message. I’m interested in any experience people here have had with implementing both pessimistic and optimistic locking. If there are any libraries, tools, or ‘how-to’s available I’m appreciate a link. Thanks

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  • Any techniques to interrupt, kill, or otherwise unwind (releasing synchronization locks) a single de

    - by gojomo
    I have a long-running process where, due to a bug, a trivial/expendable thread is deadlocked with a thread which I would like to continue, so that it can perform some final reporting that would be hard to reproduce in another way. Of course, fixing the bug for future runs is the proper ultimate resolution. Of course, any such forced interrupt/kill/stop of any thread is inherently unsafe and likely to cause other unpredictable inconsistencies. (I'm familiar with all the standard warnings and the reasons for them.) But still, since the only alternative is to kill the JVM process and go through a more lengthy procedure which would result in a less-complete final report, messy/deprecated/dangerous/risky/one-time techniques are exactly what I'd like to try. The JVM is Sun's 1.6.0_16 64-bit on Ubuntu, and the expendable thread is waiting-to-lock an object monitor. Can an OS signal directed to an exact thread create an InterruptedException in the expendable thread? Could attaching with gdb, and directly tampering with JVM data or calling JVM procedures allow a forced-release of the object monitor held by the expendable thread? Would a Thread.interrupt() from another thread generate a InterruptedException from the waiting-to-lock frame? (With some effort, I can inject an arbitrary beanshell script into the running system.) Can the deprecated Thread.stop() be sent via JMX or any other remote-injection method? Any ideas appreciated, the more 'dangerous', the better! And, if your suggestion has worked in personal experience in a similar situation, the best!

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  • REST WCF service locks thread when called using AJAX in an ASP.Net site

    - by Jupaol
    I have a WCF REST service consumed in an ASP.Net site, from a page, using AJAX. I want to be able to call methods from my service async, which means I will have callback handlers in my javascript code and when the methods finish, the output will be updated. The methods should run in different threads, because each method will take different time to complete their task I have the code semi-working, but something strange is happening because the first time I execute the code after compiling, it works, running each call in a different threads but subsequent calls blocs the service, in such a way that each method call has to wait until the last call ends in order to execute the next one. And they are running on the same thread. I have had the same problem before when I was using Page Methods, and I solved it by disabling the session in the page but I have not figured it out how to do the same when consuming WCF REST services Note: Methods complete time (running them async should take only 7 sec and the result should be: Execute1 - Execute3 - Execute2) Execute1 -- 2 sec Execute2 -- 7 sec Execute3 -- 4 sec Output After compiling Output subsequent calls (this is the problem) I will post the code...I'll try to simplify it as much as I can Service Contract [ServiceContract( SessionMode = SessionMode.NotAllowed )] public interface IMyService { // I have other 3 methods like these: Execute2 and Execute3 [OperationContract] [WebInvoke( RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json, UriTemplate = "/Execute1", Method = "POST")] string Execute1(string param); } [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] [ServiceBehavior( InstanceContextMode = InstanceContextMode.PerCall )] public class MyService : IMyService { // I have other 3 methods like these: Execute2 (7 sec) and Execute3(4 sec) public string Execute1(string param) { var t = Observable.Start(() => Thread.Sleep(2000), Scheduler.NewThread); t.First(); return string.Format("Execute1 on: {0} count: {1} at: {2} thread: {3}", param, "0", DateTime.Now.ToString(), Thread.CurrentThread.ManagedThreadId.ToString()); } } ASPX page <%@ Page EnableSessionState="False" Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="RestService._Default" %> <asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent"> <script type="text/javascript"> function callMethodAsync(url, data) { $("#message").append("<br/>" + new Date()); $.ajax({ cache: false, type: "POST", async: true, url: url, data: '"de"', contentType: "application/json", dataType: "json", success: function (msg) { $("#message").append("<br/>&nbsp;&nbsp;&nbsp;" + msg); }, error: function (xhr) { alert(xhr.responseText); } }); } $(function () { $("#callMany").click(function () { $("#message").html(""); callMethodAsync("/Execute1", "hello"); callMethodAsync("/Execute2", "crazy"); callMethodAsync("/Execute3", "world"); }); }); </script> </asp:Content> <asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent"> <input type="button" id="callMany" value="Post Many" /> <div id="message"> </div> </asp:Content> Web.config (relevant) <system.webServer> <modules runAllManagedModulesForAllRequests="true" /> </system.webServer> <system.serviceModel> <serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" /> <standardEndpoints> <webHttpEndpoint> <standardEndpoint name="" helpEnabled="true" automaticFormatSelectionEnabled="true" /> </webHttpEndpoint> </standardEndpoints> </system.serviceModel> Global.asax void Application_Start(object sender, EventArgs e) { RouteTable.Routes.Ignore("{resource}.axd/{*pathInfo}"); RouteTable.Routes.Add(new ServiceRoute("", new WebServiceHostFactory(), typeof(MyService))); }

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  • Using many mutex locks

    - by hanno
    I have a large tree structure on which several threads are working at the same time. Ideally, I would like to have an individual mutex lock for each cell. I looked at the definition of pthread_mutex_t in bits/pthreadtypes.h and it is fairly short, so the memory usage should not be an issue in my case. However, is there any performance penalty when using many (let's say a few thousand) different pthread_mutex_ts for only 8 threads?

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  • Debug.writeline locks

    - by Carra
    My program frequently stops with a deadlock. When I do a break-all and look at the threads I see that three threads are stuck in our logging function: public class Logging { public static void WriteClientLog(LogLevel logLevel, string message) { #if DEBUG System.Diagnostics.Debug.WriteLine(String.Format("{0} {1}", DateTime.Now.ToString("HH:mm:ss"), message)); //LOCK #endif //...Log4net logging } } If I let the program continue the threads are still stuck on that line. I can't see where this can lock. The debug class, string class & datetime class seem to be thread safe. The error goes away when I remove the "#if DEBUG System... #endif" code but I'm curious why this behavior happens. Thread one: public void CleanCache() { Logging.WriteClientLog(LogLevel.Debug, "Start clean cache.");//Stuck } Thread two: private void AliveThread() { Logging.WriteClientLog(LogLevel.Debug, "Check connection");//Stuck }

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  • Tomcat thread waiting on and locking the same resource

    - by Adam Matan
    Consider the following Java\Tomcat thread dump: "http-0.0.0.0-4080-4" daemon prio=10 tid=0x0000000019a2b000 nid=0x360e in Object.wait() [0x0000000040b71000] java.lang.Thread.State: WAITING (on object monitor) at java.lang.Object.wait(Native Method) - waiting on <0x00002ab5565fe358> (a org.apache.tomcat.util.net.JIoEndpoint$Worker) at java.lang.Object.wait(Object.java:485) at org.apache.tomcat.util.net.JIoEndpoint$Worker.await(JIoEndpoint.java:458) - locked <0x00002ab5565fe358> (a org.apache.tomcat.util.net.JIoEndpoint$Worker) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:484) at java.lang.Thread.run(Thread.java:662) Is this a deadlock? It seems that the same resource (0x00002ab5565fe358) is both locked and waited on - what does it mean?

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  • Android Mock Location locks GPS on status bar

    - by Mark Manickaraj
    I created an app that uses mock locations to insert GPS coordinates. After removing the test provider via: mLocationManager.clearTestProviderLocation(mocLocationProvider); mLocationManager.removeTestProvider(mocLocationProvider); mLocationManager.removeUpdates(mLocationListener); When I launch google maps for example after exiting the app the GPS location is found and then never goes away. "Location Set By GPS" always remains on the notification bar even though my app is ended. Any ideas?

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  • VB.NET Program Locks Up with Internet Explorer Opened

    - by aaronsj
    I'm using Visual Studio 2008 and developing a VB.NET application. I'm having strange lockup problems with my program, but only when Internet explorer 8 is opened. When I cover my form with another window and then uncover it, I find that it has locked up. My program has no references to IE and the only thing it even has to do with IE is using Process.Start with a web address. My program works fine and exactly as it should, but only when IE is not opened. Does anyone know why a program would lock up only while IE is running? Edit: I've done some digging and I've found the offending thread in my program. I don't know what starts this thread or what it does, but when I kill it, my program no longer freezes. The thread is one of the CreateApplicationContext threads, here is the last few items in the stack trace of that thread. 6 ntkrnlpa.exe+0x897bc 7 ntdll.dll!KiFastSystemCallRet 8 mscorwrks.dll!LogHelp_TerminateOnAssert+0x61 9 mscorwrks.dll!DllUnregisterServerInternal+0x10523 10 mscorwrks.dll!DllUnregisterServerInternal+0x10542 11 mscorwrks.dll!StrongNameErrorInfo+0x34387 12 mscorwrks.dll!StrongNameErrorInfo+0x34815 13 mscorwrks.dll!CreateApplicationContext+0xbc35 14 KERNEL32.dll!GetModuleHandleA+0xdf Process explorer says my program is using no CPU nor throwing any exceptions while it is hung.

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  • Can a thread call wait() on two locks at once in Java (6)

    - by Dr. Monkey
    I've just been messing around with threads in Java to get my head around them (it seems like the best way to do so) and now understand what's going on with synchronize, wait() and notify(). I'm curious about whether there's a way to wait() on two resources at once. I think the following won't quite do what I'm thinking of: synchronized(token1) { synchronized(token2) { token1.wait(); token2.wait(); //won't run until token1 is returned System.out.println("I got both tokens back"); } } In this (very contrived) case token2 will be held until token1 is returned, then token1 will be held until token2 is returned. The goal is to release both token1 and token2, then resume when both are available (note that moving the token1.wait() outside the inner synchronized loop is not what I'm getting at). A loop checking whether both are available might be more appropriate to achieve this behaviour (would this be getting near the idea of double-check locking?), but would use up extra resources - I'm not after a definitive solution since this is just to satisfy my curiosity.

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  • Process locks a folder

    - by Vad
    Have pretty odd situation. There are 2 applications: 1) C:\MyFolder1\First.exe 2) C:\MyFolder2\Second.exe First.exe runs Second.exe and quits. Process.Start(@"C:\MyFolder2\Second.exe"); // And exit. Seconds.exe waits a few seconds and tries to remove "C:\MyFolder1\" folder. // Wait for 5 seconds - First.exe terminated by that time for 100% Directory.Delete(@"C:\MyFolder1\", true); Action fails with “The process cannot access the file ‘C:\MyFolder1\’ because it is being used by another process.” It's able to remove the First.exe file (actually all files in the folder), but not the folder itself. Does anybody have an idea why the folder is locked by the second process?

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  • How can I break out of ssh when it locks?

    - by Wayne Werner
    Hi, I frequently ssh into my box at home from school, but usually when I change classes and my computer suspends, the pipe will be broken. However, ssh simply locks up - ^c, ^z and ^d have no effect. It's annoying to have to restart my terminal, and even more annoying to have to close and re-create a new screen window. So my question, is there an easy way to make ssh die properly (i.e. when the pipe fails "normally" it will exit with a message about a broken pipe)? Or do I have to figure out what the PID is and manually kill it? Thanks!

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  • C++ Unlocking a std::mutex before calling std::unique_lock wait

    - by Sant Kadog
    I have a multithreaded application (using std::thread) with a manager (class Tree) that executes some piece of code on different subtrees (embedded struct SubTree) in parallel. The basic idea is that each instance of SubTree has a deque that store objects. If the deque is empty, the thread waits until a new element is inserted in the deque or the termination criteria is reached. One subtree can generate objects and push them in the deque of another subtree. For convenience, all my std::mutex, std::locks and std::variable_condition are stored in a struct called "locks". The class Tree creates some threads that run the following method (first attempt) : void Tree::launch(SubTree & st, Locks & locks ) { /* some code */ std::lock_guard<std::mutex> deque_lock(locks.deque_mutex_[st.id_]) ; // lock the access to the deque of subtree st if (st.deque_.empty()) // check that the deque is still empty { // some threads are still running, wait for them to terminate std::unique_lock<std::mutex> wait_lock(locks.restart_mutex_[st.id_]) ; locks.restart_condition_[st.id_].wait(wait_lock) ; } /* some code */ } The problem is that "deque_lock" is still locked while the thread is waiting. Hence no object can be added in the deque of the current thread by a concurrent one. So I turned the lock_guard into a unique_lock and managed the lock/unlock manually : void launch(SubTree & st, Locks & locks ) { /* some code */ std::unique_lock<std::mutex> deque_lock(locks.deque_mutex_[st.id_]) ; // lock the access to the deque of subtree st if (st.deque_.empty()) // check that the deque is still empty { deque_lock.unlock() ; // unlock the access to the deque to enable the other threads to add objects // DATA RACE : nothing must happen to the unprotected deque here !!!!!! // some threads are still running, wait for them to terminate std::unique_lock<std::mutex> wait_lock(locks.restart_mutex_[st.id_]) ; locks.restart_condition_[st.id_].wait(wait_lock) ; } /* some code */ } The problem now, is that there is a data race, and I would like to make sure that the "wait" instruction is performed directly after the "deque_lock.unlock()" one. Would anyone know a way to create such a critical instruction sequence with the standard library ? Thanks in advance.

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  • Script / command to drop all connections / locks in Sybase SQL Anywhere 9?

    - by nxzr
    I've recently become responsible for administering an application which is essentially a front end to a Sybase SQL Anywhere 9 database, including the database itself. I'd like to use unload table to efficiently export the data for backup and, in the case of a few tables, ETL to get it into a reporting database / small scale data warehouse. The problem is that the client application crashes and leaves dead connections and shared locks on a pretty regular basis, which seems to prevent unload table from getting the (brief) exclusive locks it needs. Currently I use Sybase Central to verify that these connections are in fact zombies and drop them myself at the end of the day / week. Is there a command or script to drop all connections? Being able to drop everything at once after verifying that they're unneeded would be quite helpful but I haven't found a way to do it.

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  • How to find out which app locks a given USB storage device?

    - by Dimitri C.
    I'd like to unplug my USB mass storage device, but I get the following error message from Windows: Windows can't stop your 'XYZ' device because it is in use. Close any programs or windows that might be using the device, and then try again later. How can I find out which application locks the device, so I can safely unplug it without having to close all running applications first? Note: I'm working on a Windows Vista system.

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  • Ubuntu ONE (Windows BETA) locks up - What to do?

    - by Zusch
    OS: Windows XP SP3 Hardware: Dell Precision M4400 (Laptop) CPU: Core2Duo T9600 Mem: 4 GB Installer- setup, first start and account- setup of UbuntuONE Windows client passed with no problems. After restart of UbuntuONE, the CPU- usage shows 50% (100% core usage). Exit- command (from context-menu) hides the trayicon, but the program is still working excessive in background (50% cpu- / 50 MB memory- usage), until UbuntuOneClient.exe is killed by the taskmanager. What's going on ?

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  • How can i change focus when game locks it?

    - by GrizzLy
    I am playing wolfenstein:enemy territory, and if i play it in windowed mode, i can't change focus from game to something else (alt+tab doesnt work). EDIT1: As far as i could try, only ctrl+alt+Fx works (x is one number, for example F1 will switch to terminal). Could i somehow capture this kind of shortcut somewhere on X level and then send it to compiz to change focus (minimize currently focused window)? EDIT2: I found one other way, it works for Wolf:ET, it may help with other games too, if you turn on gameconsole (usually tilde key) game will release mouse lock (in windowed mode).

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