FAQ Database Discussion Community


how to decide the looping condition for wait() in Java

java,multithreading,wait,notify
I am understanding wait() in Java in regards to multithreaded, and as per the documentation, wait() should always be in a loop. I have difficult in understanding what is the condition we have to give in the loop. Typically, I have seen: synchornized(obj) { while(some_condition) { obj.wait(); } // some...

linux -c - notify the kernel from userspace as fast as possible and vice versa

c,linux,linux-kernel,mmap,notify
Context : Debian 64 bits. Making a linux-only userspace networking stack that I may release open source. Everything is ready but one last thing. The problem : I know about poll/select/epoll and use them heavily already but they are too complicated for my need and tend to add latency (few...

dijit/Tree is not updated when connected to a dojo/store/JsonRest

dynamic,dojo,notify,dijit.tree,jsonreststore
I have modified the dojo tutorial at http://dojotoolkit.org/documentation/tutorials/1.10/store_driven_tree/demo/demo.html to read from a JsonRest store. The problem is that the tree display doesn't update when I click "Add new child to selected item" e.g. on the root element, although the update worked in the original tutorial. I have compared what dojo/store/Memory...

Wait and Notify in Java threads for a given interval

java,multithreading,thread-safety,wait,notify
i am working on a usecase as below. I am new to multi threading and facing this issue with using it. I broadcast a event on network. Its received by all the listeners, and they unicast me with their information. This is received inside the call back method as below,...

java.lang.IllegalMonitorStateException whilst calling wait from synchronized block

java,multithreading,wait,notify
Before I move onto using Condition variables I'm trying to understand object wait principles. I wrote a little code to understand more but its not working as expected. What is supposed to happen is a Waiter class waits upon thread start. Meanwhile the Notifier class adds some elements to a...

Program gets halted: wait() and notify()

java,multithreading,wait,synchronized,notify
I am trying to achieve this: Created two different threads, one prints odd numbers, one prints even numbers. Once one thread prints a number, it has to wait for the other thread and so on, that is one-after-other. To achieve this, i am using synchronized block along with wait() and...

How to notify thread of changes

java,apache-commons,notify
I have created a class FolderObserver which observes a folder in my project for changes (file created/file deleted). My class is implementing the Runnable interface (I'm using the classes FileAlterationObserver, FileAlterationMonitor, FileAlterationListener from apache commons). In my main class I start a thread with my FolderObserver object as an argument....

Java: coding basic multithreading

java,multithreading,wait,notify
I'm writing a rhythm game in Java; right now I've reached the point where I'm trying to implement a metronome object. I've coded a data structure that stores 8 channels of music data into a single QuarterBeat object; these are in turn stored in groups of 64 to make 4-measure...

Exception in thread “AWT-EventQueue-0” java.lang.IllegalMonitorStateException at java.lang.Object.notify(Native Method)

java,jdialog,notify
What I'm trying to do: Launch a window to request parameters What I've tried: If I remove the vp.wait(), the window disappears. If I remove notify(), the program doesn`t wait. Here's my code: public static void main(String[] args) throws InterruptedException{ if(args.length==0){ ParamsWind vp = new ParamsWind(); vp.setVisible(true); synchronized (vp){ try...

How can a loop be completed by two thread? say loop from count=1 to count=4 by ist thread and count =5 to 8 by 2nd thread?

java,multithreading,wait,notify
Description of how i want the output : I want two threads Gaurav and john to complete a while loop(from 1 to 8), such that whichever thread starts ist, runs for 5 iterations(i.e. till count=5) , then go to sleep and then next thread completes the loop (run for count=6...

Linux - c - ipc notification without context switch and low overhead?

c,linux,ipc,notify,low-latency
Context : Linux 64bits. I am very well versed in shared memories, different IPCs mechanisms. Currently, I am seeking something that could be used in userspace to notify change between two polled processes, to save cpu cycles. I already know about futexes, eventfd, slow signals and even char devices. But...

Notify update of Tooltip Value (wpf)

wpf,xaml,binding,datagrid,notify
I have a Datagrid structure in xaml and several columns inside it: <DataGridTextColumn x:Name="QualityValueColumn" Binding="{Binding QualityValue}"> <DataGridTextColumn.CellStyle> <Style TargetType="DataGridCell"> <Setter Property="ToolTip" Value="{Binding MySelf, Converter={StaticResource ItemToTooltipConverter}}"/> <Setter Property="ToolTipService.ShowDuration" Value="48000"></Setter> <Setter Property="BorderThickness" Value="0"></Setter> </Style>...

Android threads can't get notify() to work properly using wait() and notify()

java,android,multithreading,wait,notify
So I am writing an Android application which will do a count down when the user presses a button. A thread runs the count down. My problem is that when I pause the application I want the thread to stop counting and then resume once the application is back. My...