Enabling “HTTP Keep Alive” For Faster Page Speed

Let’s begin by understanding what actually keep alive means.

Whenever there is a request for a file done by the browser from a server, one by one downloading of file takes place, i.e. after every single file download there is a break in connection which again opens to download the next file. So, the number of processes increases, which finally delays the loading of the website.

So, to resolve this issue the basic idea is to establish such a connection which ensures that all downloading of all the required files from same connection without multiple make and break of the connections.

Here HTTP keep alive play a significant role, as it enables loading of all the files in a single request via same open connection, this cuts off the continuous connecting and disconnecting time and thus leads to much faster loading of the content.

Most of the online tools read the HTTP Header of your URL and tell whether keep-alive connections are enabled by detecting the keep-alive configurations listed in the header response.

Here are some of the tools that can be used to check the Keep-Alive status:

1. Recently we used Giftofspeed tool for checking the Keep-Alive.
2. Online tools like GTmetrix notify whether keep alive is active or not
3. Other tools like varvy also notify if keep alive is in off mode.

• KeepAlive: Switches KeepAlive on or off. Use “KeepAlive on” to turn it on and “KeepAlive off” to turn it off.
• MaxKeepAliveRequests: The maximum number of requests a single persistent connection will service. A number ranging between 50 and 75 would be enough.
• KeepAliveTimeout: This determines that how long should the server wait for new requests from connected clients. The default is 15 seconds which is way too high. Set it something between 1 to 5 seconds to avoid having processes that are wasting RAM while waiting for requests.

<ifModule mod_headers.c>
Header set Connection keep-alive
</ifModule>

Add this code in your .htaccess file and it will enable keep alive for the requests.

# KeepAlive On for more than one request per connection. 
#Set to "Off" to deactivate (for new connection for every request).

KeepAlive On
# MaxKeepAliveRequests: The maximum number of requests to allow
# During a persistent connection, set MaxKeepAliveRequests to 0 to allow an unlimited amount.
# You can keep its number high to attain maximum performance.

MaxKeepAliveRequests 100

# KeepAliveTimeout: Number of seconds to wait for the next request from the
# same client on the same connection.

KeepAliveTimeout 100

For Keep Alive

The number of connections to an upstream server that remain open for each worker process. There is no default value for this.

Default: keepalive_disable msie6;
Syntax: keepalive_disable none | browser …;

For Keep Alive Timeout

How long an idle keepalive connection remains open.

Default: keepalive_timeout 75s;
Syntax: keepalive_timeout timeout [header_timeout];

For Keep Alive Number Of Request per connection

It is a number of requests a client can make over a single keepalive connection. The default value is 100, but a much higher value can be especially useful for sending a large number of requests from a single client.

Default: keepalive_requests 100;
Syntax: keepalive_requests number;

The module of Keep-alives was added to HTTP, mainly to significantly reduce the overhead of rapidly creating & closing socket connections for each new request in same session.

Let’s assume that when a page is requested, 5-7 files are needed to get loaded before page actually shows up.