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    sleep

    (PHP 4, PHP 5, PHP 7, PHP 8)

    sleep — 実行を遅延させる

    説明

    sleep(int $seconds): int

    seconds で与えられた秒数分プログラムの実行を遅延させます。

    注意:

    1秒以下の精度でプログラムの実行を遅延させる用途には、 usleep() を使って下さい。 なぜなら、sleep() は整数値を期待するためです。 たとえば sleep(0.25) は、プログラムの実行を 0 秒停止させてしまいます。

    パラメータ

    seconds

    秒単位の停止時間。 (0 以上の値でなければなりません)

    戻り値

    成功した場合にゼロを返します。

    シグナルで中断した場合、sleep() はゼロ以外の値を返します。 Windows では、この値は常に 192 (Windows API の定数 WAIT_IO_COMPLETION の値) です。 その他のプラットフォームでは、残りの遅延秒数を返します。

    エラー / 例外

    指定した seconds が負の場合、 この関数は ValueError をスローします。

    変更履歴

    バージョン 説明
    8.0.0 この関数は、負の seconds を指定すると ValueError をスローするようになりました。 これより前のバージョンでは、 E_WARNING が発生し、false を返していました。

    例

    例1 sleep() の例

    <?php

    // 現在の時刻
    echo date('h:i:s') . "\n";

    // 10 秒間遅延させる
    sleep(10);

    // 再開!
    echo date('h:i:s') . "\n";

    ?>

    この例の（10 秒後の）出力は以下のようになります。 

    05:31:23
05:31:33

    参考

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    User Contributed Notes 12 notes

    up
    50
    ash b
    10 years ago
    re: "mitigating the chances of a full bruit force attack by a limit of 30 lookups a minute."

    Not really - the attacker could do 100 requests. Each request might take 2 seconds but it doesn't stop the number of requests done. You need to stop processing more than one request every 2 seconds rather than delay it by 2 seconds on each execution.
    up
    40
    MPHH
    21 years ago
    Note: The set_time_limit() function and the configuration directive max_execution_time only affect the execution time of the script itself. Any time spent on activity that happens outside the execution of the script such as system calls using system(), the sleep() function, database queries, etc. is not included when determining the maximum time that the script has been running.
    up
    3
    John
    10 months ago
    To avoid using usleep function that is not working on every operating system, below a function that should have the same behavior :

    function wait(int $millisecond = 0) {
    if (0 !== $millisecond) {
    $seconds = (int) ($millisecond / 1000);
    $nanoSeconds = ($millisecond % 1000) * 1000000;
    time_nanosleep($seconds, $nanoSeconds);
    }
    }
    up
    33
    barlow at fhtsolutions dot com
    13 years ago
    You should put sleep into both the pass and fail branches, since an attacker can check whether the response is slow and use that as an indicator - cutting down the delay time. But a delay in both branches eliminates this possibility.
    up
    22
    Diego Andrade
    8 years ago
    Maybe obvious, but this my function to delay script execution using decimals for seconds (to mimic sleep(1.5) for example):

    <?php
    /**
    * Delays execution of the script by the given time.
    * @param mixed $time Time to pause script execution. Can be expressed
    * as an integer or a decimal.
    * @example msleep(1.5); // delay for 1.5 seconds
    * @example msleep(.1); // delay for 100 milliseconds
    */
    function msleep($time)
    {
    usleep($time * 1000000);
    }
    ?>
    up
    13
    Anonymous
    6 years ago
    Diego Andrade's msleep function is not compatible with php7's `strict_types`, cast the usleep parameter to int, and it will be,
    usleep((int)($time * 1000000));
    up
    9
    hartmut at six dot de
    24 years ago
    it is a bad idea to use sleep() for delayed output effects as

    1) you have to flush() output before you sleep

    2) depending on your setup flush() will not work all the way to the browser as the web server might apply buffering of its own or the browser might not render output it thinks not to be complete

    netscape for example will only display complete lines and will not show table parts until the </table> tag arrived

    so use sleep if you have to wait for events and don't want to burn to much cycles, but don't use it for silly delayed output effects!
    up
    2
    Anonymous
    10 years ago
    If you are having issues with sleep() and usleep() not responding as you feel they should, take a look at session_write_close()

    as noted by anonymous on comments;
    "If the ajax function doesn't do session_write_close(), then your outer page will appear to hang, and opening other pages in new tabs will also stall."
    up
    0
    ealexs at gmail dot com
    2 years ago
    From my testing calling sleep(0); will do a `thread spin`.
    It would be nice if this was to be put explicitly in the documentation as it is useful. You can do the minimum wait without overloading the CPU thread.
    up
    0
    Anonymous
    3 years ago
    I wrote a simple method for sleeping with a float, which also allows you to do milliseconds (via fractional seconds).

    <?php
    function sleepFloatSecs($secs) {
    $intSecs = intval($secs);
    $microSecs = ($secs - $intSecs) * 1000000;

    if(    $intSecs > 0) {
    sleep($intSecs);
    }
    if(    $microSecs > 0) {
    usleep($microSecs);
    }
    }
    ?>

    And testing on my machine it works perfectly:

    <?php
    $x     = [0.100,0.250,0.5,1.0,1.5,2.0,2.5];

    foreach(    $x as $secs) {
    $t = microtime(true);
    sleepFloatSecs($secs);
    $t = microtime(true) - $t;
    echo     "$secs \t => \t $t\n";
    }
    ?>

    Output:

    <?php
    0.1     => 0.10017800331116
    0.25     => 0.25016593933105
    0.5     => 0.50015211105347
    1     => 1.0001430511475
    1.5     => 1.5003218650818
    2     => 2.000167131424
    2.5     => 2.5002470016479
    ?>
    up
    -5
    manu7772 at gmail dot com
    3 years ago
    Sleep method with parameter in milliseconds :

    public static function ms_sleep($milliseconds = 0) {
    if($milliseconds > 0) {
    $test = $milliseconds / 1000;
    $seconds = floor($test);
    $micro = round(($test - $seconds) * 1000000);
    if($seconds > 0) sleep($seconds);
    if($micro > 0) usleep($micro);
    }
    }
    up
    -3
    smcbride at msn dot com
    3 years ago
    An example of using sleep to run a set of functions at different intervals. This is not a replacement for multi-threading, but it could help someone that wants to do something cheap. You don't have to use eval(). It is just used as an example. This is different than running a standard 1 second sleep loop, due to sleeping longer does not consume as much CPU.

    <?php

    // current time
    echo date('h:i:s') . "\n";

    // Some example functions
    function function_a() { echo 'function_a called @ ' . date('h:i:s') . PHP_EOL; }
    function     function_b() { echo 'function_b called @ ' . date('h:i:s') . PHP_EOL; }
    function     function_c() { echo 'function_c called @ ' . date('h:i:s') . PHP_EOL; }

    // Add some timers (in seconds) with function calls
    $sleeptimers = array();
    $sleeptimers['5'][0]['func'] = 'function_a();';
    $sleeptimers['10'][0]['func'] = 'function_b();';
    $sleeptimers['15'][0]['func'] = 'function_c();';

    // Process the timers
    while(true) {
    $currenttime = time();
    reset($sleeptimers);
    $mintime = key($sleeptimers);
    foreach(    $sleeptimers as $SleepTime => $Jobs) {
    foreach(    $Jobs as $JobIndex => $JobDetail) {
    if(!isset(    $JobDetail['lastrun'])) {
    $sleeptimers[$SleepTime][$JobIndex]['lastrun'] = time();
    if(    $SleepTime < $mintime) $mintime = $SleepTime;
    } elseif((    $currenttime - $JobDetail['lastrun']) >= $SleepTime) {
    eval(    $JobDetail['func']);
    $lastrun = time();
    $sleeptimers[$SleepTime][$JobIndex]['lastrun'] = $lastrun;
    $mysleeptime = $SleepTime - ($currenttime - $lastrun);
    if(    $mysleeptime < 0) $mysleeptime = 0;
    if((    $currenttime - $JobDetail['lastrun']) < $mintime) $mintime = $mysleeptime; // account for length of time function runs
    echo 'Sleep time for function ' . $JobDetail['func'] . ' = ' . $mysleeptime . PHP_EOL;
    }
    }
    }
    echo     'Sleeping for ' . $mintime . ' seconds' . PHP_EOL;
    sleep($mintime);
    }

    ?>
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