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

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.

Hide div after a few seconds

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.

Best timing method in C?

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?

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

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?

differences between "d = dict()" and "d = {}"

$ python2.7 -m timeit 'd={}'
10000000 loops, best of 3: 0.0331 usec per loop
$ python2.7 -m timeit 'd=dict()'
1000000 loops, best of 3: 0.19 usec per loop

Why use one over the other?

Timing algorithm: clock() vs time() in C++

For timing an algorithm (approximately in ms), which of these two approaches is better:

clock_t start = clock();
algorithm();
clock_t end = clock();
double time = (double) (end-start) / CLOCKS_PER_SEC * 1000.0;

Or,

time_t start = time(0);
algorithm();
time_t end = time(0);
double time = difftime(end, start) * 1000.0;

Also, from some discussion in the C++ channel at Freenode, I know clock has a very bad resolution, so the timing will be zero for a (relatively) fast algorithm. But, which has better resolution time() or clock()? Or is it the same?

jQuery Timed Event

Is it possible, using jQuery, to fire off an event to set a div tag's text after n. seconds?

Thanks! George

How can I find the execution time of a section of my program in C?

I'm trying to find a way to get the execution time of a section of code in C. I've already tried both time() and clock() from time.h, but it seems that time() returns seconds and clock() seems to give me milliseconds (or centiseconds?) I would like something more precise though. Is there a way I can grab the time with at least microsecond precision?

This only needs to be able to compile on Linux.

What is the best way to measure Client Side page load times?

I'm looking to monitor the end user experience of our website and link that with timing information already logged on the server side. My assumption is that this will require javascript to to capture time stamps at the start of request (window.onbeforeunload) and at the end of loading (window.onload). Basically this - "Measuring Web application response time: Meet the client"

1. Is there a better approach?
2. What kind of performance penalty should I be expecting (order of magnitude)?
3. How good are the results?

Executing code at regularly timed intervals in Clojure

What's the best way to make code run at regular intervals in Clojure ? I'm currently using java.util.concurrent.ScheduledExecutorService, but that's Java - is there a Clojure way of scheduling code to run at regular intervals, after a delay, cancellably ? All the Clojure code examples I've seen use Thread/sleep, which also seems too Java.

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

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 Stopwatch would be more accurate than calculating the difference between a start and end time using System.DateTime.Now?

BTW, I'm not talking about a tenths of a percent. I get about a 15-20% difference.

timeit versus timing decorator

I'm trying to time some code. First I used a timing decorator:

#!/usr/bin/env python

import time
from itertools import izip
from random import shuffle

def timing_val(func):
    def wrapper(*arg, **kw):
        '''source: http://www.daniweb.com/code/snippet368.html'''
        t1 = time.time()
        res = func(*arg, **kw)
        t2 = time.time()
        return (t2 - t1), res, func.__name__
    return wrapper

@timing_val
def time_izip(alist, n):
    i = iter(alist)
    return [x for x in izip(*[i] * n)]

@timing_val
def time_indexing(alist, n):
    return [alist[i:i + n] for i in range(0, len(alist), n)]

func_list = [locals()[key] for key in locals().keys()
             if callable(locals()[key]) and key.startswith('time')]
shuffle(func_list)  # Shuffle, just in case the order matters

alist = range(1000000)
times = []
for f in func_list:
    times.append(f(alist, 31))

times.sort(key=lambda x: x[0])
for (time, result, func_name) in times:
    print '%s took %0.3fms.' % (func_name, time * 1000.)

yields

% test.py
time_indexing took 73.230ms.
time_izip took 122.057ms.

And here I use timeit:

%  python - m timeit - s '' 'alist=range(1000000);[alist[i:i+31] for i in range(0, len(alist), 31)]'
10 loops, best of 3:
    64 msec per loop
% python - m timeit - s 'from itertools import izip' 'alist=range(1000000);i=iter(alist);[x for x in izip(*[i]*31)]'
10 loops, best of 3:
    66.5 msec per loop

Using timeit the results are virtually the same, but using the timing decorator it appears time_indexing is faster than time_izip.

What accounts for this difference?

Should either method be believed?

If so, which?

How to program a real-time accurate audio sequencer on the iphone?

I want to program a simple audio sequencer on the iphone but I can't get accurate timing. The last days I tried all possible audio techniques on the iphone, starting from AudioServicesPlaySystemSound and AVAudioPlayer and OpenAL to AudioQueues.

In my last attempt I tried the CocosDenshion sound engine which uses openAL and allows to load sounds into multiple buffers and then play them whenever needed. Here is the basic code:

init:

int channelGroups[1];
channelGroups[0] = 8;
soundEngine = [[CDSoundEngine alloc] init:channelGroups channelGroupTotal:1];

int i=0;
for(NSString *soundName in [NSArray arrayWithObjects:@"base1", @"snare1", @"hihat1", @"dit", @"snare", nil])
{
    [soundEngine loadBuffer:i fileName:soundName fileType:@"wav"];
    i++;
}

[NSTimer scheduledTimerWithTimeInterval:0.14 target:self selector:@selector(drumLoop:) userInfo:nil repeats:YES];

In the initialisation I create the sound engine, load some sounds to different buffers and then establish the sequencer loop with NSTimer.

audio loop:

- (void)drumLoop:(NSTimer *)timer
{
for(int track=0; track<4; track++)
{
    unsigned char note=pattern[track][step];
    if(note)
        [soundEngine playSound:note-1 channelGroupId:0 pitch:1.0f pan:.5 gain:1.0 loop:NO];
}

if(++step>=16)
    step=0;

}

Thats it and it works as it should BUT the timing is shaky and instable. As soon as something else happens (i.g. drawing in a view) it goes out of sync.

As I understand the sound engine and openAL the buffers are loaded (in the init code) and then are ready to start immediately with alSourcePlay(source); - so the problem may be with NSTimer?

Now there are dozens of sound sequencer apps in the appstore and they have accurate timing. I.g. "idrum" has a perfect stable beat even in 180 bpm when zooming and drawing is done. So there must be a solution.

Does anybody has any idea?

Thanks for any help in advance!

Best regards,

Walchy

Thanks for your answer. It brought me a step further but unfortunately not to the aim. Here is what I did:

nextBeat=[[NSDate alloc] initWithTimeIntervalSinceNow:0.1];
[NSThread detachNewThreadSelector:@selector(drumLoop:) toTarget:self withObject:nil];

In the initialisation I store the time for the next beat and create a new thread.

- (void)drumLoop:(id)info
{
    [NSThread setThreadPriority:1.0];

    while(1)
    {
        for(int track=0; track<4; track++)
        {
            unsigned char note=pattern[track][step];
            if(note)
                [soundEngine playSound:note-1 channelGroupId:0 pitch:1.0f pan:.5 gain:1.0 loop:NO];
        }

        if(++step>=16)
            step=0;     

        NSDate *newNextBeat=[[NSDate alloc] initWithTimeInterval:0.1 sinceDate:nextBeat];
        [nextBeat release];
        nextBeat=newNextBeat;
        [NSThread sleepUntilDate:nextBeat];
    }
}

In the sequence loop I set the thread priority as high as possible and go into an infinite loop. After playing the sounds I calculate the next absolute time for the next beat and send the thread to sleep until this time.

Again this works and it works more stable than my tries without NSThread but it is still shaky if something else happens, especially GUI stuff.

Is there a way to get real-time responses with NSThread on the iphone?

Best regards,

Walchy

What happens when QueryPerformanceCounter is called?

I'm looking into the exact implications of using QueryPerformanceCounter in our system and am trying to understand it's impact on the application. I can see from running it on my 4-core single cpu machine that it takes around 230ns to run. When I run it on a 24-core 4 cpu xeon it takes around 1.4ms to run. More interestingly on my machine when running it in multiple threads they don't impact each other. But on the multi-cpu machine the threads cause some sort of interaction that causes them to block each other. I'm wondering if there is some shared resource on the bus that they all query? What exactly happens when I call QueryPerformanceCounter and what does it really measure?

Javascript, setTimeout loops?

So I am working on a music program that requires multiple javascript elements to be in sync with another. I've been using setInterval which works really well initially however over time the elements gradually become out of sync which with a music program is bad.

I've read online that setTimeout is more accurate, and you can have setTimeout loops somehow however I have not found a generic version that illustrates how this is possible. Could someone just show me a basic example of using setTimeout to loop something indefinitely.

Thank you. Alternatively, if there is a way to achieve more synchronous results with setInterval or even another function, please let me know.

EDIT:

Basically I have some functions like such:

//drums
setInterval(function {
//code for the drums playing goes here
},8000);

//chords
setInterval(function {
//code for the chords playing goes here
},1000);

//bass
setInterval(function {
//code for the bass playing goes here
},500);

It works super well initially but over the course of about a minute, the sounds become noticeably out of sync as I've read happens with setInterval, I've read that setTimeout can be more consistently accurate.