synchronization

CouchDB db-per-user with shared data scalability

由 戏子无情 提交于 2019-12-11 02:33:43
问题 I have an application with the following architecture: The master couchdb is required to share data between the users. EG: If user-1 writes data to the cloud, this replicates to the master and back to user-2 and user-3. However, as the user base increases so do the number of cloud user couchDBs, which results in a large number of replication links between the cloud user couchDBs and the master couchDB. I believe this can lead to a huge bottleneck. Is there a better way to approach this

Does joining a std::thread flush memory?

由 送分小仙女□ 提交于 2019-12-11 02:28:39
问题 Consider this example: #include <string> #include <chrono> #include <atomic> #include <thread> #include <iostream> std::string some_variable; void writer_thread() { std::this_thread::sleep_for( std::chrono::seconds( 1 ) ); some_variable = "done"; } int main() { { std::thread w( &writer_thread ); w.join(); } std::cout << some_variable; } Is it necessary for me to add a synchronization mechanism to ensure that some_variable is correctly read from main() ? Said differently: does joining or

Scala actor to non-actor interaction (or synchronizing messages from an actor to a servlet)

由 浪子不回头ぞ 提交于 2019-12-11 02:14:09
问题 I have the following scala code: package dummy import javax.servlet.http.{HttpServlet, HttpServletRequest => HSReq, HttpServletResponse => HSResp} import scala.actors.Actor class DummyServlet extends HttpServlet { RNG.start override def doGet(req: HSReq, resp: HSResp) = { def message = <HTML><HEAD><TITLE>RandomNumber </TITLE></HEAD><BODY> Random number = {getRandom}</BODY></HTML> resp.getWriter().print(message) def getRandom: String = {var d = new DummyActor;d.start;d.getRandom} } class

Synchronization and notify order of execution and scope

由 孤街醉人 提交于 2019-12-11 01:37:21
问题 1) Does a thread relinquish it's lock as soon as notify is invoked within that threads synchronized code block, or once the synchronized code block is exited? For instance, it seems like without specifying thread priority, my Process class will execute from top to bottom. Produce will be called first, it will do stuff, then wait(); consume will run, and then it hits notify(), which will print "Done" or will there be a 5 second delay first, then "Done" will be printed? 2) Also, if I had a

Interprocess Communication in C++

由 和自甴很熟 提交于 2019-12-11 01:36:41
问题 I have a simple c++ application that generates reports on the back end of my web app (simple LAMP setup). The problem is the back end loads a data file that takes about 1.5GB in memory. This won't scale very well if multiple users are running it simultaneously, so my thought is to split into several programs : Program A is the main executable that is always running on the server, and always has the data loaded, and can actually run reports. Program B is spawned from php, and makes a simple

java rmi deadlock

由 霸气de小男生 提交于 2019-12-11 00:33:37
问题 I just have started to program with java rmi and I face the following problem in my code: My server has two Remote methods which are implemented in general as follows: public class ServerImpl extends UnicastRemoteObject implements Server{ .... Synchronized void foo(){ aClient.Foo3();} Synchronized void foo1(){ .... } } My clients have one remote method which is implemented as follows: public class ClientImpl extends UnicastRemoteObject implements Client{ .... void Foo3(){theServer.foo1();} }

Is synchronization needed when manipulating different array(object array) indices

由 倖福魔咒の 提交于 2019-12-10 23:34:35
问题 In the context if Java, I have a code like this, MyObject[] array; and in different threads i have a code like this array[i] = new MyObject(val); If I ensure that each of my threads use different values of " i " then would I need to synchronize the above statement to take care of race conditions? 回答1: Race conditions are only an issue if two threads may read and modify the same variable concurrently. As long as you are sure that each thread uses a different range of indices, and the

what will happen to the request for synchronized block in java if monitor is already locked?

由 拈花ヽ惹草 提交于 2019-12-10 23:34:06
问题 What will happen to the request for synchronized block from different threads, if current threads holds the monitor? example: say below is the synchronized block: ABC.java: public class ABC { ... public void setValue(){ Example object = Example.getinstance(); // Example is a singleton class which maintains the arraylist of objects of class ABC synchronized (object) { object.storeObject(this); } } ... } suppose there are three threads T1,T2,T3 which is creating objects for ABC class e.g: obj1

Can't sync Gradle in Android Studio in Iran

由 ⅰ亾dé卋堺 提交于 2019-12-10 22:25:48
问题 I use Android Studio version 1.5.1, and I'm trying to compile 'com.android.volley:volley:1.0.0' in build.gradle, but I can't sync Gradle. I think this error is because of my Internet connection or access being blocked from my country (Iran). 回答1: Yes, it's because Google has been blocked in Iran since 2012. You can use a proxy app like Shadowsocks to change your country. After activating your proxy app, in Android Studio go to file->setting->Appearance & Behavior->System Setting->HTTP Proxy

Synchronization for several goroutines using channels

由 烈酒焚心 提交于 2019-12-10 21:08:25
问题 I need to start a number of workers with single task queue and single result queue. Each worker should be started in different goroutine. And I need to wait till all workers will be finished and task queue will be empty before exiting from program. I have prepare small example for goroutine synchronization. The main idea was that we count tasks in queue and waiting for all workers to finish jobs. But current implementation sometime miss values. Why this happends and how to solve the problem?
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