If you're like me, you've probably read a dozen or two articles about PHP performance in your career. Many of them are quite good, but some are simply flat out wrong, or misinformed.

One of the old truisms that has been repeated for as long as I can recall is "don't use readfile() if you have big files, because it reads the whole file into memory and your server will explode." The usual advice is to manually stream a file, like so:

<span style="color: #000000"><span style="color: #0000BB">&lt;?php<br>$fp </span><span style="color: #007700">= </span><span style="color: #0000BB">fopen</span><span style="color: #007700">(</span><span style="color: #DD0000">'bigfile.tar'</span><span style="color: #007700">, </span><span style="color: #DD0000">'rb'</span><span style="color: #007700">);<br>while (!</span><span style="color: #0000BB">feof</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">)) {<br> print </span><span style="color: #0000BB">fread</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #0000BB">1024</span><span style="color: #007700">);<br>}<br></span><span style="color: #0000BB">fclose</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">);<br></span><span style="color: #0000BB">?&gt;</span></span>

There's just one problem with that age-old truism: It's not true.

read more