wait

深入理解pthread_cond_wait、pthread_cond_signal

由 陌路散爱 提交于 2020-01-01 00:23:10
转自：http://blog.csdn.net/yeyuangen/article/details/37593533 ===============================man pthread_cond_wait的解释========================== LINUX环境下多线程编程肯定会遇到需要条件变量的情况，此时必然要使用pthread_cond_wait()函数。但这个函数的执行过程比较难于理解。 pthread_cond_wait()的工作流程如下（以MAN中的EXAMPLE为例）： Consider two shared variables x and y, protected by the mutex mut, and a condition vari- able cond that is to be signaled whenever x becomes greater than y. int x,y; pthread_mutex_t mut = PTHREAD_MUTEX_INITIALIZER; pthread_cond_t cond = PTHREAD_COND_INITIALIZER; Waiting until x is greater than y is performed as follows: pthread_mutex

How to wait for user's action in JavaFX (in the same stage)

由 ↘锁芯ラ 提交于 2019-12-31 05:41:07
问题 Do you know how to wait for the user's input in a for loop? I don't mean the showAndWait() method, because I am not opening a new dialogue stage for the user. So for example, each round of the for loop should be waiting for the user to push a button before going ahead with the next round. How is it possible? Many thanks! UPDATE: Now it came to my mind, that it would work with a while(buttonNotPressed){} but is it a good solution? I mean the while loop is running in this case as crazy until

The purpose of the wait() in parent c

由 我只是一个虾纸丫 提交于 2019-12-31 05:38:10
问题 I am new to processes in linux and c. I am using this straightforward example: #include <stdio.h> #include <stdlib.h> #include <unistd.h> int main(int argc, const char * argv[]) { pid_t child_pid_or_zero = fork(); //fork returns twice if(child_pid_or_zero < 0) { //if fork returns a number smaller than zero, something wrong happened perror("Something wrong happened\n"); exit(-1); } if(child_pid_or_zero > 0) { //if fork returns a number greater than zero, this is the parent process printf("I'm

Wait() & Sleep() Not Working As Thought

由 牧云@^-^@ 提交于 2019-12-31 05:26:15
问题 Using JavaFX 8.0 and JRE 1.8.0 u45 in IntelliJ, I created a basic pixel editor app. I have two windows(stages). One is a 32x128 matrix of Circle Objects placed in a Grid Pane and the other, a Tools widow; I have one Controller.java . Using the mouse, the Tools window provides tools to draw lines, rectangles, etc. and a menu for Setup, Files and Playlists. The Files menu presents the user with Open, SaveAs and Delete. To view a saved pixel art file, the user clicks Open and via the

Waiting for a function to finish execution and using the results

由 被刻印的时光 ゝ 提交于 2019-12-31 05:05:24
问题 Here's the scenario I have an activity(A) which has a button and textview. I have another class(B) with methods for performing various functions. After creating an instance of class B, one of it's public method is called from A when the button is clicked. The method takes a while to execute(it invokes another time consuming private methods in the class) and returns the value of one of the private members of class B. The trouble is that the method returns the initial value of the member and

Redirect after loading images

由 大憨熊 提交于 2019-12-31 04:18:11
问题 So I have been recently developing a site, The problem is the backgrounds for each page are images, and as a result, on slower connections (which is the case of some of the target audience) the images load progressivly as they are downloaded, to resolve this I am trying to make a preloading page that does the following : Loads the Images Once the loading is done, redirects the user to the requested page <script type="text/javascript"> <!--//--><![CDATA[//><!-- var images = new Array() var

How do I make Java wait for a method to finish before continuing?

由 我的未来我决定 提交于 2019-12-31 03:19:07
问题 So my problem is that I need these methods to run one after another but I cannot work out how to make the methods wait before being run. Any help is appreciated. Thank you. Here is my code: public void startMoving() throws InterruptedException { moveEnemy("right",3); wait(); moveEnemy("down",3); wait(); moveEnemy("right",2); wait(); moveEnemy("up",1); wait(); moveEnemy("right",2); wait(); moveEnemy("up",2); wait(); moveEnemy("right",2); wait(); moveEnemy("down",4); wait(); moveEnemy("left",1)

How do I run tasks in parallel and select the first result that satisfies a given condition in C#? [duplicate]

由 纵饮孤独 提交于 2019-12-30 07:03:08
问题 This question already has answers here : TPL wait for task to complete with a specific return value (2 answers) Closed 4 years ago . There are three tasks that I wish to run in parallel. I wish to examine the result of the first task that finished and do a check to decide if the result is good . If yes, I cancel all other tasks and return this result, if not, I will wait for next completed task and check if that is good and do the same if it is. (Think of being good as some simple check on a

Why do we need to synchronize on the same object for notify() to work

由 ▼魔方 西西 提交于 2019-12-30 04:51:09
问题 I was getting java.lang.IllegalMonitorStateException . I referred this question and it solved my problem. The first answer is To be able to call notify() you need to synchronize on the same object. synchronized (someObject) { someObject.wait(); } /* different thread / object */ synchronized (someObject) { someObject.notify(); } My question is why we need to synchronize on the same object ad how it works? As far as my understanding goes when we say synchronized (someObject) { someObject.wait()

wait child process but get error: 'pid is not a child of this shell'

由 六月ゝ 毕业季﹏ 提交于 2019-12-30 02:47:07
问题 I write a script to get data from HDFS parrallel，then I wait these child processes in a for loop, but sometimes it returns "pid is not a child of this shell". sometimes, it works well。It's so puzzled. I use "jobs -l" to show all the jobs run in the background. I am sure these pid is the child process of the shell process, and I use "ps aux" to make sure these pids is note assign to other process. Here is my script. PID=() FILE=() let serial=0 while read index_tar do echo $index_tar | grep
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