timing | 易学教程

How to make a proper server tick?

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问题 I am trying to make a game server which updates after a certain period. import time last_time = time.time() tick = 1 time_since_last_update = 0 while True: new_time = time.time() dt = new_time - last_time time_since_last_update += dt last_time = new_time if time_since_last_update > tick: print(\"Magic happens\") time_since_last_update = 0 When I do this thing, python consumes 100% computing power on one of the cores. I don\'t really understand why is this happening and how to fix this if

Multi-threading benchmarking issues

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问题 I have written a code that randomly generates two matrices from dimensions 2x2 up to 50x50. I am then recording the time it takes for each matrix multiplication from dimensions 2 up to 50. I record this time 100 times to get a good average for each case 2 -50. The program first starts off by multiplying the matrices sequentially and records the average execution time in a csv file. It then moves on to parallel matrix multiplication using pthreads and records the average execution times in a

How accurate is Thread.sleep?

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I'm studying computer hardware where we learn that using a hardware timer gets more accurate results than a software delay. I've written a software delay in assembly for 1 millisecond and I can start a process that repeats every millisecod using this delay and with a counter do something else every 100th millisecond, and this technique would be less accurate than using a hardware timer that I got builtin with my hardware that I'm going to use now. So I wonder how accurate is the timing that is builtin with Java? We have System.currentTimeMillis and Thread.sleep and these might not use hardware

Best timing method in C?

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问题 What is the best way to time a code section with high resolution and portability? /* Time from here */ ProcessIntenseFunction(); /* to here. */ printf(\"Time taken %d seconds %d milliseconds\", sec, msec); Is there a standard library that would have a cross-platform solution? 回答1: I think this should work: #include <time.h> clock_t start = clock(), diff; ProcessIntenseFunction(); diff = clock() - start; int msec = diff * 1000 / CLOCKS_PER_SEC; printf("Time taken %d seconds %d milliseconds",

Is setTimeout with no delay the same as executing the function instantly?

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问题 I am looking at some existing code in a web application. I saw this: window.setTimeout(function () { ... }) Is this the same as just executing the function content right away? 回答1: It won't necessarily run right away, neither will explicitly setting the delay to 0. The reason is that setTimeout removes the function from the execution queue and it will only be invoked after JavaScript has finished with the current execution queue. console.log(1); setTimeout(function() {console.log(2)});

Windows 7 timing functions - How to use GetSystemTimeAdjustment correctly?

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问题 I ran some tests using the GetSystemTimeAdjustment function on Windows 7, and got some interesting results which I cannot explain. As fas as I understand, this method should return if the system time is synchronized periodically and if it is, at which interval and with which increment it is updated (see GetSystemTimeAdjustment function on MSDN). From this I follow that if I query the system time for example using GetSystemTimeAsFileTime repeatingly I should either get no change (the system

How accurate is Thread.sleep?

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问题 I\'m studying computer hardware where we learn that using a hardware timer gets more accurate results than a software delay. I\'ve written a software delay in assembly for 1 millisecond and I can start a process that repeats every millisecod using this delay and with a counter do something else every 100th millisecond, and this technique would be less accurate than using a hardware timer that I got builtin with my hardware that I\'m going to use now. So I wonder how accurate is the timing

Stopwatch vs. using System.DateTime.Now for timing events [duplicate]

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问题 This question already has answers here : Is DateTime.Now the best way to measure a function's performance? (15 answers) Closed 6 years ago . I wanted to track the performance of my code so I stored the start and end time using System.DateTime.Now . I took the difference between the two as the time my code to execute. I noticed though that the difference didn\'t appear to be accurate. So I tried using a Stopwatch object. This turned out to be much, much more accurate. Can anyone tell me why

Hide div after a few seconds

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问题 I was wondering, how in jquery am I able to hide a div after a few seconds? Like Gmail\'s messages for example. I\'ve tried my best but am unable to get it working. 回答1: This will hide the div after 1 second (1000 milliseconds). setTimeout(function() { $('#mydiv').fadeOut('fast'); }, 1000); // <-- time in milliseconds #mydiv{ width: 100px; height: 100px; background: #000; color: #fff; text-align: center; } <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script

How do I time a method's execution in Java?

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问题 How do I get a method\'s execution time? Is there a Timer utility class for things like timing how long a task takes, etc? Most of the searches on Google return results for timers that schedule threads and tasks, which is not what I want. 回答1: There is always the old-fashioned way: long startTime = System.nanoTime(); methodToTime(); long endTime = System.nanoTime(); long duration = (endTime - startTime); //divide by 1000000 to get milliseconds. 回答2: I go with the simple answer. Works for me.