I'm trying to write a function that pings a few hundred addresses and returns their values (milliseconds). So far I've achieved the initial idea which is to ping and get the result but the problem arises when using the same code for hundreds of addresses, the PHP page stalls until it either times out or reaches the last ping command.
I would be glad if I could get some suggestions to output the results progressively, here is my current code:
<?php
// "for" loop added according to suggestion for browser compatibility (IE, FF, CHR, OPR, SFR)
for($i = 0; $i < 5000; $i++)
{
echo ' ';
}
function GetPing($ip = NULL) {
// Returns the client ping if no address has been passed to the function
if(empty($ip)) {
$ip = $_SERVER['REMOTE_ADDR'];
}
// Check which OS is being run by the client
if(getenv('OS') == 'Windows_NT') {
//echo '<b>Detected local system:</b> Windows NT/2000/XP/2003/2008/Vista/7<p>';
$exec = exec("ping -n 1 -l 32 -i 128 " . $ip);
return end(explode(' ', $exec));
}
else {
//echo '<b>Detected local system:</b> Linux/Unix<p>';
$exec = exec("ping -c 1 -s 32 -t 128 " . $ip);
$array = explode('/', end(explode('=', $exec )));
return ceil($array[1]) . 'ms';
}
// ob_flush and flush added according to suggestion for buffer output
ob_flush();
flush();
}
// Added to test 20 sequential outputs
for($count = 0; $count < 20; $count++)
echo GetPing('8.8.8.8') . '<div>';
?>
After some feedback, I've added a for loop as well as ob_flush() and flush() to my script and I've also set output_buffering to 0 in php.ini. It seems to work for most browsers that I tested so far (IE8, Firefox 12, Chrome 19, Opera 11, Safari 5). It seems the current code is now working as intended but any suggestion to improve on it is immensely appreciated.
Thank you for your feedback.
this is just a guess; I've written years ago a very wobbly chat script that used output buffering as well (and fetching new messages in while(true) loop) ..
While doing this I've encountered the same problems that sometimes the script stalled (blank screen), sometimes it took a while until the characters appeared and additionally this was also browser specific.
Here are the relevant code snippets I've added to the script to have it work with IE6 and FF2 (as I said, years ago ...)
<?php
// End output buffering
ob_end_flush();
// IE and Safari Workaround
// They will only display the webpage if it's completely loaded or
// at least 5000 bytes have been "printed".
for($i=0;$i<5000;$i++)
{
echo ' ';
}
while( ... )
{
echo 'Message';
ob_flush();
flush();
}
?>
It worked for me, so maybe you could give it a try as well. (Altough I have no idea how modern browsers and server infrastrucutre will behave to this).
I think what you may be looking for is progressively running and outputting the script, rather than asynchronous functions.
See Is there a way to make PHP progressively output as the script executes?
Related
It works fine but later sometime the count just goes down to random
number. My guess is my code cannot process multiple visits at a time.
Where increment heppens
Where it displays the count
<?php
$args_loveteam = array('child_of' => 474);
$loveteam_children = get_categories($args_loveteam);
if(in_category('loveteams', $post->ID)){
foreach ($loveteam_children as $loveteam_child) {
$post_slug = $loveteam_child->slug;
echo "<script>console.log('".$post_slug."');</script>";
if(in_category($loveteam_child->name)){
/* counter */
// opens file to read saved hit number
if($loveteam_child->slug == "loveteam-mayward"){
$datei = fopen($_SERVER['DOCUMENT_ROOT']."/wp-content/themes/inside-showbiz-Vfeb13.ph-updated/countlog-".$post_slug."-2.txt","r");
}else{
$datei = fopen($_SERVER['DOCUMENT_ROOT']."/wp-content/themes/inside-showbiz-Vfeb13.ph-updated/countlog-".$post_slug.".txt","r");
}
$count = fgets($datei,1000);
fclose($datei);
$count=$count + 1 ;
// opens file to change new hit number
if($loveteam_child->slug == "loveteam-mayward"){
$datei = fopen($_SERVER['DOCUMENT_ROOT']."/wp-content/themes/inside-showbiz-Vfeb13.ph-updated/countlog-".$post_slug."-2.txt","w");
}else{
$datei = fopen($_SERVER['DOCUMENT_ROOT']."/wp-content/themes/inside-showbiz-Vfeb13.ph-updated/countlog-".$post_slug.".txt","w");
}
fwrite($datei, $count);
fclose($datei);
}
}
}
?>
I would at least change your code to this
foreach ($loveteam_children as $loveteam_child) {
$post_slug = $loveteam_child->slug;
echo "<script>console.log('".$post_slug."');</script>";
if($loveteam_child->slug == "loveteam-mayward"){
$filename = "{$_SERVER['DOCUMENT_ROOT']}/wp-content/themes/inside-showbiz-Vfeb13.ph-updated/countlog-{$post_slug}.txt";
}else{
$filename = "{$_SERVER['DOCUMENT_ROOT']}/wp-content/themes/inside-showbiz-Vfeb13.ph-updated/countlog-{$post_slug}-2.txt";
}
$count = file_get_contents($filename);
file_get_contents($filename, ++$count, LOCK_EX);
}
You could also try flock on the file to get a lock before modifying it. That way if another process comes along it has to wait on the first one. But file_put_contents works great for things like logging where you may have many processes competing for the same file.
Database should be ok, but even that may not be fast enough. It shouldn't mess up your data though.
Anyway hope it helps. This is kind of an odd question, concurrency can be a real pain if you have a high chance of process collisions and race conditions etc etc.
However as I mentioned (in the comments) using the filesystem is probably not going to provide the consistency you need. Probably the best for this may be some kind of in memory storage such as Redis. But that is hard to say without full knowing what you use it for. For example if it should persist on server reboot.
Hope it helps, good luck.
I have a php script that calls a go script. It gets results every 1-2 seconds, and print's them. Using php's exec and output, I only get the results when the program finishes. Is there a way I can check the output to see when it changes and output that while it's still running?
Something like this, but pausing the execution?:
$return_status = 0;
$output = [];
$old_output = ["SOMETHING ELSE"];
while ($return_status == 0) {
exec($my_program,$output,$return_status); #somehow pause this?
if $output != $old_output {
echo($output);
$old_output = $output;
}
}
Yes. Use the popen() function to get a file handle for the command's output, then read from it a line at a time.
I'm trying to learn long poll and I'm using following PHP script:
<?php
$lastMod = filemtime('test.txt');
$counter = 10;
while ($counter > 0) {
if (filemtime('test.txt') !== $lastMod) {
echo file_get_contents('./test.txt');
exit;
}
$counter--;
sleep(1);
}
echo $lastMod;
But no matter what I do or try, it doesn't do anything when I change test.txt content during script execution.
I would be really happy if somebody told me where is the mistake.
The filemtime result is cached during runtime, so you need to reset it explicitly using clearstatcache().
Run it right before your if.
From the docs:
Note: The results of this function are cached. See clearstatcache()
for more details.
My code:
#ini_set('zlib.output_compression',0);
#ini_set('implicit_flush',1);
#ob_end_clean();
set_time_limit(0);
function show_status($done, $total, $size=30) {
static $start_time;
if($done > $total) return;
if(empty($start_time)) $start_time=time();
$now = time();
$perc=(double)($done/$total);
$bar=floor($perc*$size);
$status_bar="[";
$status_bar.=str_repeat("=", $bar);
if($bar<$size){
$status_bar.=">";
$status_bar.=str_repeat(" ", $size-$bar);
} else {
$status_bar.="=";
}
$disp=number_format($perc*100, 0);
$status_bar.="] $disp% $done/$total";
#$rate = ($now-$start_time)/$done;
$left = $total - $done;
$eta = round($rate * $left, 2);
$elapsed = $now - $start_time;
$status_bar.= " remaining: ".number_format($eta)." sec. elapsed: ".number_format($elapsed)." sec.";
echo "$status_bar\r";
flush();
if($done == $total) {
echo "\n";
}
}
The call is simply show_status($count, $total_count); - its not working on my server for some reason, but I know the code above works (came from the net, and Ive used it before on another server). Problem Im having now on my current server is that its not outputting it per execution, only seeing the end result (100%) once its processed everything.
Output buffering is set to Off (even though this shouldnt be needed because its being executed via CLI)
zlib.output_compression set to Off
see first 4 lines of code to other settings im trying to explicitly set as well
Also have "SetEnv no-gzip dont-vary" in a .htaccess as this is apparently another cause of flush() not working
What am I missing!? This isnt a browser issue because once again, Im running this via the CLI!
PS: Im running this on WAMP with php 5.3.6 with apache 2.2.16
After looking into the script I believe there is nothing wrong with it. After running this test I was presented with a single line showing me the status at 8% complete:
show_status(10, 1000);
show_status(40, 1000);
show_status(80, 1000);
echo "\n";
However if I run this script:
show_status(10, 1000);
sleep(5);
show_status(40, 1000);
sleep(5);
show_status(80, 1000);
echo "\n";
The output line is periodically REPLACED ever 5 seconds with status 1%, 4%, 8%
I imagine what ever you are tracking the status of is simple completing far faster than the output is rendering and so you are seeing a completed result.
flush() has no effect on CLI.
I have a .php script that I use for creating the list of my products.
I am on shared hosting, so I can't do a lot of queries otherwise I get a blank page.
This is how I use my script now:
script.php?start=0&end=500&indexOfFile=0 ->> make a product0.txt file with first 500 products
script.php?start=501&end=1000&indexOfFile=1 ->> product1.txt file with another 500 products
script.php?start=1001&end=1500&indexOfFile=2 ->> product2.txt file with last 500 products
How can I modify the script so it will make all these files automatically, so that I don't have to change each time the link manually?
I would like to click a button which will do this:
make the product0.txt file with the first 500 products
wait 5 seconds
make the product1.txt file with with another 500 products
wait 5 seconds
make the product2.txt file with the last 500 products
use:
sleep(NUMBER_OF_SECONDS);
before starting your actions, use
sleep(5);
or:
usleep(NUMBER_OF_MICRO_SECONDS);
In Jan2018 the only solution worked for me:
<?php
if (ob_get_level() == 0) ob_start();
for ($i = 0; $i<10; $i++){
echo "<br> Line to show.";
echo str_pad('',4096)."\n";
ob_flush();
flush();
sleep(2);
}
echo "Done.";
ob_end_flush();
?>
i use this
$i = 1;
$last_time = $_SERVER['REQUEST_TIME'];
while($i > 0){
$total = $_SERVER['REQUEST_TIME'] - $last_time;
if($total >= 2){
// Code Here
$i = -1;
}
}
you can use
function WaitForSec($sec){
$i = 1;
$last_time = $_SERVER['REQUEST_TIME'];
while($i > 0){
$total = $_SERVER['REQUEST_TIME'] - $last_time;
if($total >= 2){
return 1;
$i = -1;
}
}
}
and run code =>
WaitForSec(your_sec);
Example :
WaitForSec(5);
OR
you can use sleep
Example :
sleep(5);
I am on shared hosting, so I can't do a lot of queries otherwise I get a blank page.
That sounds very peculiar. I've got the cheapest PHP hosting package I could find for my last project - and it does not behave like this. I would not pay for a service which did. Indeed, I'm stumped to even know how I could configure a server to replicate this behaviour.
Regardless of why it behaves this way, adding a sleep in the middle of the script cannot resolve the problem.
Since, presumably, you control your product catalog, new products should be relatively infrequent (or are you trying to get stock reports?). If you control when you change the data, why run the scripts automatically? Or do you mean that you already have these URLs and you get the expected files when you run them one at a time?
In https://www.php.net/manual/es/function.usleep.php
<?php
// Wait 2 seconds
usleep(2000000);
// if you need 5 seconds
usleep(5000000);
?>