synchronization

问题 I know why and how to use {async:false} in jQuery AJAX request. But what I need is how this works synchronously? What is the magic behind this? 回答1: Because the native XMLHTTPRequest object provides the possibility to make synchronous requests: async An optional boolean parameter, defaulting to true, indicating whether or not to perform the operation asynchronously. You can assume that it does that by pausing the thread in which JS runs. 回答2: My best guess, is that when async is false, then

问题 I have a desktop application that runs on a network and every instance connects to the same database. So, in this situation, how can I implement a mutex that works across all running instances that are connected to the same database? In other words, I don't wan't that two+ instances to run the same function at the same time. If one is already running the function, the other instances shouldn't have access to it. PS: Database transaction won't solve, because the function I wan't to mutex doesn

问题 This question was migrated from Software Engineering Stack Exchange because it can be answered on Stack Overflow. Migrated 8 years ago . I'm not a professional programmer, but I do some small solo projects and I would like some versioning and syncing, but going through the process of remember to commit and checkout (on different computers) is more of a hassle than, say, keeping code in a dropbox folder that automatically uploads to the cloud upon file change. Using the current copy is

问题 I have been trying to solve a problem involving thread communication using wait() and notify(). Basically i have 2 threads T1 and T2 and i want them to be executed in the following order T1 , T2, T1, T2 ..... How can i achieve that? Actual Problem: There are 2 threads T1 - which prints odd numbers (say 1 - 100) and T2 - which prints even numbers (1 - 100). Now, the output should be 1, 2, 3, 4 , 5 , .... 100 回答1: You describe a Producer-Consumer pattern. It's java implementations described in

问题 When one must synchronize programs (shell scripts) via file system, I have found an flock -based solution to be recommended (should also work on NFS). The canonical example for usage from within a script (from http://linux.die.net/man/1/flock) is: ( flock -s 200 # ... commands executed under lock ... ) 200>/var/lock/mylockfile I don't quite get why this whole construct ensures atomicity. In particular, I am wondering in which order flock -s 200 and 200>/var/lock/mylockfile are executed when e

问题 As javascript(including form submission) is synchronous and single thread model except ajax calls. Is that right? But i am facing one issue regarding this. I am submitting the form at line 1 and then closing the pop up. what happens is self.close get called before form submission. So here it is behaving in asynch mode. Is form submission a asynchronous process? If yes how can i make the code after form submission synchronous?(I dont want to use setTimeOut and ajax) Here is my relevant jsp

问题 As javascript(including form submission) is synchronous and single thread model except ajax calls. Is that right? But i am facing one issue regarding this. I am submitting the form at line 1 and then closing the pop up. what happens is self.close get called before form submission. So here it is behaving in asynch mode. Is form submission a asynchronous process? If yes how can i make the code after form submission synchronous?(I dont want to use setTimeOut and ajax) Here is my relevant jsp

问题 The Java language spec defines semantics of final fields in section 17.5: The usage model for final fields is a simple one. Set the final fields for an object in that object's constructor. Do not write a reference to the object being constructed in a place where another thread can see it before the object's constructor is finished. If this is followed, then when the object is seen by another thread, that thread will always see the correctly constructed version of that object's final fields.

问题 I'm facing an issue regarding Java method synchronization. Let's hope I can explain it briefly: I have two different methods in two different classes, in two different packages. Something like: Package1 |_Class1 \MethodA Package2 |_Class2 \MethodB Ok, so now I need to synchronize these two methods, which are not threads . So far, I have two different approaches: Shared semaphore . Create a shared static semaphore outside Package1 and Package2 , something like: package Package3; public class

问题 Here's the scenario: I have a multi threaded java web application which is running inside a servlet container. The application is deployed multiple times inside the servlet container. There are multiple servlet containers running on different servers. Perhaps this graph makes it clear: server1 +- servlet container +- application1 | +- thread1 | +- thread2 +- application2 +- thread1 +- thread2 server2 +- servlet container +- application1 | +- thread1 | +- thread2 +- application2 +- thread1 +-