synchronization

问题 I'm trying to figure out how if rsyncing files is atomic. I couldn't find any confirmation about it. Due to rsync being able to send only deltas, I was under the impression that it also updates only parts of the live files. On the other hang DJB recommends rsync for synchronising live .cdb files and I've found this post ( http://lists.samba.org/archive/rsync/2002-April/002210.html ) which both would imply that the new file is created, then moved over to the proper location. Can someone point

问题 I have two windows application, one is a windows service which create EventWaitHandle and wait for it. Second application is a windows gui which open it by calling EventWaitHandle.OpenExisting() and try to Set the event. But I am getting an exception in OpenExisting. The Exception is "Access to the path is denied". windows Service code EventWaitHandle wh = new EventWaitHandle(false, EventResetMode.AutoReset, "MyEventName"); wh.WaitOne(); Windows GUI code try { EventWaitHandle wh =

问题 I want to run a thread for sending email periodically. In the same program, I am creating processes to do another task. When I create the task, thread from original process is copied to these sub processes and I end up receiving multiple emails instead of one. How can I make sure that thread I run in main program is not copied to the sub processes that are created? 来源： https://stackoverflow.com/questions/19320756/prevent-multiple-instances-of-threads-for-multiprocessing-python

问题 Does it lock the file before it deletes it? Does it need to? If it does not perform file locking how can I make it safe between multiple processes? 回答1: Maybe this link will explain better. As far as I understand, deletion is an atomic operation so it does not need to lock the file. However, upon looking further, I found this link which shows the OS dependent nature of the delete operation. On Windows, it will necessarily need the file to be without a lock to delete it while on Linux you can

问题 I have two activities where they have almost same data, I am using same Adapter, But the problem is how to sync data. E.g. Activity A has recyclerview where it has like buttons in each row with unique id. Activity B also have same recyclerview but with some filter mechanism so it is not going to show all row, my question is how to handle like button state in Activity A and Activity B , such that if I click on activity B's like button than activity A's like button will automatically gets

问题 I read sync.Pool design, but find it is two logic, why we need localPool to solve lock compete. We can just use chan to implement one. Using channel is 4x times faster than sync.pool ! Besides pool can clear object, what advantage does it have? This is the pool implementation and benchmarking code: package client import ( "runtime" "sync" "testing" ) type MPool chan interface{} type A struct { s string b int overflow *[2]*[]*string } var p = sync.Pool{ New: func() interface{} { return new(A)

问题 This question already has answers here : What's the difference between InterlockedCompareExchange Release() and Acquire()? (2 answers) Closed 5 years ago . Can someone explain the difference betweeen these three atomic operations? InterlockedIncrement InterlockedIncrementAcquire InterlockedIncrementNoFence I can't seem to find any documentation on what they mean other than "uses acquire symantecs" which I don't understand. Thanks. 回答1: Going off the documentation, InterlockedIncrement

问题 I get the below error *** Retrieving the COM class factory for component with CLSID {046C184F-2188-4C99-A95A-9C0DCDC19050} failed due to the following error: 80040154 Class not registered (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG)). *** while using the Microsoft Sync Services on execute of the below statement . I get the error only when I run from the IIS that is http;//localhost/S71/default.aspx etc. But if I run by pressing F5 from my visual studio it works fine . All other

问题 There is a JAVAFX Scrollpane which contains a treeview. Inside the treeview, i have a few vboxs. Their height can change. Firstly, there was a problem : when i move a vbox thanks to a drag operation, the scrollbar which belongs to the scrollpane didn't want to move. In order to resolve this problem, i have done a few researches here. I found a solution. The code is below private ScrollBar getVerticalScrollbar() { ScrollBar result = null; for (Node n : scrollPane.lookupAll(".scroll-bar")) { if

问题 Post Model <?php namespace App\Model\User; use Illuminate\Database\Eloquent\Model; class Post extends Model { public function tags(){ return $this->belongsToMany('App\Model\User\Tag','post__tags', 'post_id', 'tag_id'); } public function categories() { return $this->belongsToMany('App\Model\User\Category','category__posts','post_id', 'category_id'); } } Category Model <?php namespace App\Model\User; use Illuminate\Database\Eloquent\Model; class Category extends Model { public function posts(){