PHP输出缓冲抛出警告

Question

I have to output results while PHP script is running:

ob_implicit_flush(true);
ob_start();
for ($i=0; $i<5; $i++) {
    echo $i . ' - ';
    ob_end_flush();
    flush();
    sleep(1);
}

This is working but throwing warnings:

Notice: ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush in ...

How to fix that?

Answer 1

In the first loop you are ending the buffer. If you want to do that, you should start a new buffer in each loop.

ob_implicit_flush(true);
for ($i=0; $i<5; $i++) {
    ob_start();
    echo $i . ' - ';
    ob_end_flush();
    flush();
    sleep(1);
}

This is a neater way to use buffering. It is also more performant as you are only using 1 buffer. If you do not need to flush on each loop, you could skip the ob_flush within the loop and use ob_end_flush instead of ob_end_clean.

ob_implicit_flush(true);
ob_start();
for ($i=0; $i<5; $i++) {
    echo $i . ' - ';
    ob_flush();
    flush();
    sleep(1);
}
ob_end_clean();