How to flush output after each echo call

Question

I have a php script that only produces logs to the client  When I echo something  I want it to be transferred to client on-the-fly   Because while the script is processing  the page is blank  I had already played around with ob start   and ob flush    but they didn t work   What s the best solution   PS  it is a little dirty to put a flush at the end of the echo call     EDIT  Neither the Answers worked  PHP or Apache Fault

User · Answer

I m late to the discussion but I read that many people are saying appending flush    at the end of each code looks dirty  and they are right   Best solution is to disable deflate  gzip and all buffering from Apache  intermediate handlers and PHP  Then in your php ini you should have               output buffering   Off             zlib output compression   Off             implicit flush   Off   Temporary solution is to have this in your php ini IF you can solve your problem with flush    but you think it is dirty and ugly to put it everywhere   implicit flush   On   If you only put it above in your php ini  you don t need to put flush    in your code anymore

User · Answer

So here s what I found out   Flush would not work under Apache s mod gzip or Nginx s gzip because  logically  it is gzipping the content  and to do that it must buffer content to gzip it  Any sort of web server gzipping would affect this  In short  at the server side we need to disable gzip and decrease the fastcgi buffer size  So    In php ini   output buffering   Off  zlib output compression   Off  In nginx conf   gzip  off   proxy buffering  off     Also have these lines at hand  especially if you don t have access to php ini    ini set  zlib output compression  0     ini set  implicit flush  1     ob end clean     set time limit 0     Last  if you have it  comment the code bellow   ob start  ob gzhandler     ob flush      PHP test code   ob implicit flush 1    for   i 0   i lt 10   i          echo  i          this is to make the buffer achieve the minimum size in order to flush data     echo str repeat     1024 64        sleep 1

User · Answer

Why not make a function to echo  like this   function fecho  string     echo  string   ob flush

User · Answer

Note if you are on certain shared hosting sites like Dreamhost you can t disable PHP output buffering at all without going through different routes      Changing the output buffer cache If you are using PHP FastCGI  the PHP   functions flush    ob flush    and ob implicit flush   will not   function as expected  By default  output is buffered at a higher level   than PHP  specifically  by the Apache module mod deflate which is   similar in form function to mod gzip        If you need unbuffered output  you must either use CGI  instead of   FastCGI  or contact support to request that mod deflate is disabled   for your site    https   help dreamhost com hc en-us articles 214202188-PHP-overview

User · Answer

The correct function to use is flush      lt html gt   lt body gt   lt p gt  Hello  I am waiting for the next message    lt br   gt   lt  php flush    sleep 5     gt  I am the next message  lt br   gt   lt  php flush    sleep 5     gt  And I am the last message  Good bye   lt  p gt   lt  body gt   lt  html gt    Please note that there is a  problem  with IE  which only outputs the flushed content when it is at least 256 byte  so your first part of the page needs to be at least 256 byte

User · Answer

Anti-virus software may also be interfering with output flushing  In my case  Kaspersky Anti-Virus 2013 was holding data chunks before sending it to the browser  even though I was using an accepted solution

User · Answer

I had a similar thing to do  Using     ini set  output buffering   0       off  ini set  zlib output compression   0       off ini set  implicit flush   1       on      did make the output flushing frequent in my case   But I had to flush the output right at a particular point in a loop that I run   so using both   ob flush    flush      together worked for me      I wasn t able to   turn off  output buffering  with   ini set       had to turn it directly   in php ini  phpinfo   shows its setting   as  no value  when turned off  is that   normal

User · Answer

For those coming in 2018   The ONLY Solution worked for me    lt  php      if  ob get level      0  ob start        for   i   0   i lt 10   i              echo   lt br gt  Line to show            echo str pad    4096    n                ob flush            flush            sleep 2              echo  Done         ob end flush      gt    and its very important to keep de  4096  part because it seems that  fills  the buffer

User · Answer

This works fine for me  Apache 2 4 PHP 7 0     ob end clean    echo  lorem ipsum      flush    sleep 5   echo   lt br gt dolor      flush    sleep 5   echo   lt br gt sit amet

User · Answer

Flushing seemingly failing to work is a side effect of automatic character set detection   The browser will not display anything until it knows the character set to display it in  and if you don t specify the character set  it need tries to guess it  The problem being that it can t make a good guess without enough data  which is why browsers seem to have this 1024 byte  or similar  buffer they need filled before displaying anything   The solution is therefore to make sure the browser doesn t have to guess the character set    If you re sending text  add a    charset utf-8  to its content type  and if it s HTML  add the character set to the appropriate meta tag

User · Answer

One thing that is not often mentionned is gzip compression that keeps turned ON because of details in various hosting environments   Here is a modern approach  working with PHP-FPM as Fast CGI  which does not need  htaccess rewrite rule or environment variable    In php ini or  user ini    output buffering   0 zlib output compression   0 implicit flush   true output handler      In PHP script    header  Content-Encoding  none       Disable gzip compression ob end flush       Stop buffer ob implicit flush 1      Implicit flush at each output command   See this comment on official PHP doc for ob end flush   need

User · Answer

I ve gotten the same issue and one of the posted example in the manual worked  A character set must be specified as one of the posters here already mentioned  http   www php net manual en function ob-flush php 109314  header   Content-type  text html  charset utf-8     echo  Begin     lt br   gt    for   i   0    i  lt  10    i           echo  i     lt br   gt        flush        ob flush        sleep 1     echo  End     lt br   gt

User · Answer

what you want is the flush method  example   echo  log to client    flush

User · Answer

Try this   while   ob end flush           ob implicit flush true    echo  first line visible to the browser   echo   lt br   gt     sleep 5    echo  second line visible to the browser after 5 secs     Just notice that this way you re actually disabling the output buffer for your current script  I guess you can reenable it with ob start    i m not sure    Important thing is that by disabling your output buffer like above  you will not be able to redirect your php script anymore using the header   function  because php can sent only once per script execution http headers   You can however redirect using javascript  Just let your php script echo following lines when it comes to that           echo   lt script type  text javascript  gt            echo  window location href     url               echo   lt  script gt            echo   lt noscript gt            echo   lt meta http-equiv  refresh  content  0 url    url      gt            echo   lt  noscript gt             exit

User · Answer

Sometimes  the problem come from Apache settings  Apache can be set to gzip the output  In the file  htaccess you can add for instance    SetEnv no-gzip 1

User · Answer

This is my code   work for PHP7    private function closeConnection          apache setenv  no-gzip   1        ini set  zlib output compression   0        ini set  implicit flush   1        ignore user abort true       set time limit 0        ob start           do initial processing here     echo json encode   ans    gt  true         header  Connection  close        header  Content-Length      ob get length         ob end flush        ob flush        flush

User · Answer

Edit   I was reading the comments on the manual page and came across a bug that states that ob implicit flush does not work and the following is a workaround for it   ob end flush       CODE THAT NEEDS IMMEDIATE FLUSHING  ob start      If this does not work then what may even be happening is that the client does not receive the packet from the server until the server has built up enough characters to send what it considers a packet worth sending     Old Answer   You could use ob implicit flush which will tell output buffering to turn off buffering for a while   ob implicit flush true      CODE THAT NEEDS IMMEDIATE FLUSHING  ob implicit flush false

[php] How to flush output after each `echo` call?

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