I'm reading lines of text that can come in any order. The problem is that the output can actually be indentical to the previous output. How can I detect this, without sorting the output first? Is there some kind of hash function that can take identical input, but in any order, and still produce the same result? ...
What could be the cause of JVM thread dumps that show threads waiting to lock on a monitor, but the monitors do not have corresponding locking threads? Java 1.5_14 on Windows 2003 ...
I need to enumerate though generic IList<> of objects. The contents of the list may change, as in being added or removed by other threads, and this will kill my enumeration with a "Collection was modified; enumeration operation may not execute." What is a good way of doing threadsafe foreach on a IList<>? prefferably without cloning the...
I am working on a cocoa software and in order to keep the GUI responsive during a massive data import (Core Data) I need to run the import outside the main thread. Is it safe to access those objects even if I created them in the main thread without using locks if I don't explicitly access those objects while the thread is running. ...
There are various documents describing threading on Solaris/Linux, but nowwhere describing the Windows implementation. I have a passing interest in this, it seems strange that something so critical is (seemingly) not documented. Threading is not the same on different OS' - "Write Once, Run Anywhere" isn't true for threading. See http:/...
Hello! I was wondering if there are any code or class libraries out there on how to implement multithreading or "green threading" in ActionScript. As you've might seen, Scott Peterson is developing some kind of toolset, but I haven't found any more info on this other than his performance on the Adobe MAX Chicago event. Regards Niclas ...
What are the pros / cons of using pthread_cond_wait or using a semaphore ? I am waiting for a state change like this : pthread_mutex_lock(&cam->video_lock); while(cam->status == WAIT_DISPLAY) { pthread_cond_wait(&cam->video_cond, &cam->video_lock); } pthread_mutex_unlock(&cam->video_lock); Using a properly initi...
Is there a realistic way of implementing a multi-threaded model in php whether truly or just simulating it. Some time back it was suggested that you can force the operating system to load another instance of the php executable and handle other simultaneous processes. The problem with this is that when the php code finished executing the...
I understand about race conditions and how with multiple threads accessing the same variable, updates made by one can be ignored and overwritten by others, but what if each thread is writing the same value (not different values) to the same variable; can even this cause problems? Could this code: GlobalVar.property = 11; (assuming that...
Can anyone provide a good explanation of the volatile keyword in C#? Which problems does it solve and which it doesn't? In which cases will it save me the use of locking? ...
Is there a way of doing a non-blocking pthread_join? Some sort of timed join would be good to. I'll try to clarify the question: I'm coding the shutdown of a multithreaded server. If everything goes as it should all the threads exit by their own, but there's a small chance that a thread gets stuck. In this case it would be convenient ...
Multithread algorithms are notably hard to design/debug/prove. Dekker's algorithm is a prime example of how hard it can be to design a correct synchronized algorithm. Tanenbaum's Modern operating systems is filled with examples in its IPC section. Does anyone have a good reference (books, articles) for this? Thanks! ...
In my SWT Java app I often want to return information from inside a Display.syncExec() call. The best way I've found so far to do this is: final ArrayList<Integer> result = new ArrayList<Integer>(); GUI.display().syncExec(new Runnable(){ public void run() { MessageBox mb = /* ... */; /* set up messagebox */ result.add(mb.open...
As someone who is just starting to learn the intricacies of computer debugging, for the life of me, I can't understand how to read the Stack Text of a dump in Windbg. I've no idea of where to start on how to interpret them or how to go about it. Can anyone offer direction to this poor soul? ie (the only dump I have on hand with me actua...
In the C programming language and Pthreads as the threading library; do variables/structures that are shared between threads need to be declared as volatile? Assuming that they might be protected by a lock or not (barriers perhaps). Does the pthread POSIX standard have any say about this, is this compiler-dependent or neither? Edit to ...
When can 64-bit writes be guaranteed to be atomic, when programming in C on an Intel x86-based platform (in particular, an Intel-based Mac running MacOSX 10.4 using the Intel compiler)? For example: unsigned long long int y; y = 0xfedcba87654321ULL; /* ... a bunch of other time-consuming stuff happens... */ y = 0x12345678abcdefULL; I...
I'd like to be able to open a TDataSet asynchronously in its own thread so that the main VCL thread can continue until that's done, and then have the main VCL thread read from that TDataSet afterwards. I've done some experimenting and have gotten into some very weird situations, so I'm wondering if anyone has done this before. I've seen...
Any ideas how to determine the number of active threads running in ExecutorService? ...
In .NET, after this code, what mechanism stops the Thread object from being garbage collected? new Thread(Foo).Start(); GC.Collect(); Yes, it's safe to assume something has a reference to the thread, I was just wandering what exactly. For some reason Reflector doesn't show me System.Threading, so I can't dig it myself (I know MS relea...
I couldn't find a decent ThreadPool implementation for Ruby, so I wrote mine (based partly on code from here: http://snippets.dzone.com/posts/show/3276 , but changed to wait/signal and other implementation for ThreadPool shutdown. However after some time of running (having 100 threads and handling about 1300 tasks), it dies with deadlock...