faster fopen or file_get_contents?

Question

i am running multiple websites with high traffic , as a requirement , all images are downloaded via image.php?id=IMAGE_ID_HERE . If you ever done that before , you know that that file will be reading the file image and echoing it to the browser with special headers .

My problem is , the load on the server is very high (150-200) and TOP command shows multiple instances of image.php , so image.php is running slow !

the problem probably is fopen loading the image to the memory before sending it to the client. How to read a file and pass it through directly?

Thank you guys

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UPDATE

After you optimized the code, used caching wherever possible, do create a CDN . couple of servers, sync methods, load balancers and no need to worry about requests anymore :)

Solution

Why dont you cache the image content with apc ?

if(!apc_exists('img_'.$id)){
    apc_store('img_'.$id,file_get_content(...));
}

echo apc_fetch('img_'.$id);

this way image content will not be read from your disk more than once.

Comments

[Admin]

apc is hard to setup correctly. but it could be a good solution!

[Paté]

Well if the website as lots of hits than I/O on disk is high due to concurent file_get_contents, storing the content in ram would get rid of that

[Admin]

@Col.Shrapnel reading from Memory is faster than reading from Disk

[Your Common Sense]

there is not a sign of the I/O peak in the question. Go figure. It clearly says that it's CPU utilization above the limits.

[Paté]

In my experience lots of I/O is never good for load performance. If this guy has a load of 200 on this particular script than he has high IO because of the way the file are served. I'm not saying it will fix his issues but It's worth a shot IMO.

[Rami Dabain]

if you're getting like 5000 image requests/second , that would be a problem for the memory if APC is memory-based cache !!! specially if you have thousands of images !!!

[Paté]

I believe the issue is not the number of requests / seconds but more the size of all the images, you could also couple that with a RoundRobin solution. I know facebook uses memcache to cache some of their profile image so there is a reason why...

[Rami Dabain]

with the 5000 images /second ... i meant deferent images not the same , otherwise i would have cached them