scheduling

问题 When a process is in execution, the contents of the PCB (which is in kernel memory space?) are loaded onto the CPU registers, and status registers , kernel stack pointers , user stack pointers , etc. When there is a context switch to another process, the current "context" is stored back in the PCB and a switch is made to the new PCB. Now when the kernel wants to bring back this PCB back into "context", how does it find this PCB, which is in the memory now? What information helps the kernel in

问题 I'm writing an application and I'd like it to somehow schedule an email to be sent at a later date (likely an hour after it is run). The programming language will be Python or Java. Any open-source tools available for that purpose? EDIT: I forgot to mention it's to be run after a test run, so the application will already be down and I believe the Quartz solution wouldn't work. Would this be possible? Ideally, I'd like to hear that SMTP protocol has some hidden stuff that allows this, and

问题 I ask though I doubt there is any such system. Basically I need to schedule tasks to execute at some point in the future (usually no more than a few seconds or possibly minutes from now), and have some way of cancelling that request unless too late. Ie. code that would look like this: var x = Scheduler.Schedule(() => SomethingSomething(), TimeSpan.FromSeconds(5)); ... x.Dispose(); // cancels the request Is there any such system in .NET? Is there anything in TPL that can help me? I need to run

问题 With a friend of mine, we disagree on how synchronization is handled at userspace level (in the pthread library). a. I think that during a pthread_mutex_lock, the thread actively waits. Meaning the linux scheduler rises this thread, let it execute his code, which should looks like: while (mutex_resource->locked); Then, another thread is scheduled which potentially free the locked field, etc. So this means that the scheduler waits for the thread to complete its schedule time before switching

问题 With a friend of mine, we disagree on how synchronization is handled at userspace level (in the pthread library). a. I think that during a pthread_mutex_lock, the thread actively waits. Meaning the linux scheduler rises this thread, let it execute his code, which should looks like: while (mutex_resource->locked); Then, another thread is scheduled which potentially free the locked field, etc. So this means that the scheduler waits for the thread to complete its schedule time before switching

问题 I am looking everywhere (Modern C++ design & co) but I can't find a nice way to store a set of callbacks that accept different arguments and operate on different classes. I need this because I would like every object of my application to have the possibility to defer the execution of one of its methods to a master Clock object that, keeping track of the current time, can call this methods in the right moment. The code I am aiming for is something along the lines of: In the void

问题 I am trying to implement an app which assigns s students to l labs in g lab groups. The constraints are: 1:students shall work with new students for every lab. 2:all students shall be lab leader once. 2 is not solvable if the students can't be divided evenly in the lab groups. Therfore it is acceptable if the "odd" students never get to be lab leader. I have tried two approaches but I am not happy yet.: Tabu search, which solves 1 but has problems solving 2 ( I actually first solve 1 and then

问题 I'm a little new to threading, so you'll have to forgive the naiveté of this question. How is pthread_join implemented and how does it effect thread scheduling? I always pictured pthread_join implemented with a while loop, simply causing the calling thread to yield until the target thread completes. Like this (very approximate pseudocode): atomic bool done; thread_run { do_stuff(); done = true; } thread_join { while(!done) { thread_yield(); // basically, make the thread that calls "join" on /

问题 This is my 1st time trying Spring3's @Scheduled , but found I cannot commit to DB. This is my code : @Service public class ServiceImpl implements Service , Serializable { @Inject private Dao dao; @Override @Scheduled(cron="0 0 * * * ?") @Transactional(rollbackFor=Exception.class) public void hourly() { // get xxx from dao , modify it dao.update(xxx); } } I think it should work , I can see it starts-up hourly and load xxx from DB , but data is not committed to DB. There's been tx:annotation

问题 How can I execute an action (maybe an Intent) on every specified time (e.g. Every day on 5AM)? It has to stay after device reboots, similar to how cron works. I am not sure if I can use AlarmManager for this, or can I? 回答1: If you want it to stay after the device reboots, you have to schedule the alarm after the device reboots. You will need to have the RECEIVE_BOOT_COMPLETED permission in your AndroidManifest.xml <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" /> A