Process fread hang on STDOUT
Posted: Thu Apr 09, 2009 7:53 pm
Let's say I have the following:
and helloWorld.class was compiled from a source that looks like this:
Running on Windows XP, the proc_open function will use cmd.exe to execute the command.
$pipe[1] is STDOUT and the while loop will break when the newline sequence is printed.
This works because java's System.out.println function prints the string "Hello, World!" and then outputs "\r\n".
However, If it weren't for this delimiter, fread would hang because it never finds an EOF character.
I have tried using stream_set_timeout on $pipe[1] but it does not make a difference. Why can't I make the stream timeout or prevent the reading from continuing after there is nothing left to buffer in STDOUT?
Code: Select all
$cmd = "java helloWorld";
$spec = array(0=>array('pipe','r'), 1=>array('pipe','w'), 2=>array('error-output.txt','a'));
$prc = proc_open($cmd, $spec, $pipe, getcwd());
if(is_resource($prc)) {
ob_start();
while(!feof($pipe[1])) {
usleep(1000);
$out = fread($pipe[1], 128);
if(strlen($out)==0) {
break;
}
else if($out == "\r\n") {
echo "\r\n";
ob_flush(); flush();
break;
}
echo $out;
ob_flush(); flush();
}
}
Code: Select all
public class helloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
$pipe[1] is STDOUT and the while loop will break when the newline sequence is printed.
This works because java's System.out.println function prints the string "Hello, World!" and then outputs "\r\n".
However, If it weren't for this delimiter, fread would hang because it never finds an EOF character.
I have tried using stream_set_timeout on $pipe[1] but it does not make a difference. Why can't I make the stream timeout or prevent the reading from continuing after there is nothing left to buffer in STDOUT?