LiteSpeed Web Server is Event-Driven 2019-12-13 16:59:00 LiteSpeed Web Server's event-driven architecture vs. Apache's process-based: Fewer processes means less overhead, more connections, and no hardware upgrade required.

Event-Driven vs. Process-Based Web Servers

Fewer processes means less overhead and more connections with no hardware upgrade required

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The Event-Driven Advantage

The biggest difference between LiteSpeed Web Server and Apache is in the way that they handle connections: LiteSpeed Web Server utilizes an event-driven architecture and Apache is process-based.

  • Apache creates a new process or thread for every connection. This is a model which requires a lot of overhead.
  • LiteSpeed Web Server, with its event-driven architecture, serves all connections with few processes, saving resources.
  • This efficient method allows you to serve significantly more connections, faster, and without upgrading your hardware.

A Detailed Discussion of Event-Driven vs. Process-Based Servers

more overhead

Process-Based = Exponentially More Overhead

LiteSpeed Web Server and Apache are built upon different architectures. Apache comes from an older breed of process-based servers. In essence, Apache starts a new process (or thread) to handle every connection it gets. More connections means more threads. For every connection that requires PHP, Apache must start a new PHP process, increasing memory usage exponentially. As the number of connections rises, so does the burden on your Apache server. Access to your site slows down, and visitors leave, deciding it's not worth it to wait for your pages to load.

light weight and efficient

Event-Driven = Lightweight and Efficient

The antidote to all of this is an event-driven architecture. LiteSpeed handles all the connections it gets with one process (or, in some cases, very few processes). This one process stays open and handles all events that pop up — new requests coming in and new dynamic responses ready to go out. LiteSpeed Web Server concerns itself not with creating new processes to handle every aspect of every connection, but with reacting to events that occur.

all types of content

A Clear Advantage for all Types of Content

For static content (like images, CSS, HTML), the advantage is obvious: instead of consuming the overhead required for a new process for each request, LiteSpeed's event-driven model employs its one process to handle the requests as they come in. This is faster and consumes significantly less CPU and memory than Apache.

For web applications (like PHP) and database processes (like MySQL), the interaction is complex, but is still far more efficient than a process-based model:

  • LiteSpeed Web Server fields requests and forwards them to external processes.
  • LiteSpeed does not wait around for the dynamic responses, but instead continues to field more requests (both static and dynamic)
  • When an external process response is ready, LiteSpeed Web Server gets a callback (a new event to which it must react)
  • LiteSpeed sends the external response back to the requesting client.

During all of this, LSAPI, LiteSpeed's server API, keeps control over the number of processes being created for web applications, and reuses them wherever possible, further increasing CPU and memory efficiency.

low cpu usage

Consistently Low CPU Usage in Heavy Traffic

When dealing with tens of thousands of concurrent connections, would you rather field the requests and responses with a few processes? Or would you rather create a separate process for every one of those connections? The answer is clear. An event-driven server's CPU and memory usage do rise under heavy traffic conditions, but not exponentially like they do with Apache's process-based server. An event-driven model allows for faster content delivery because the server skips the overhead of creating new processes and has more memory left for handling database and external applications. Most importantly, it allows for consistently low CPU (load) and memory usage, even during traffic spikes or DDoS attacks.

Coffee Making

Coffee Making - The Coffee Shop Analogy

  • process based

    The Process-Based Coffee Shop

    Each employee serves one customer; They take the customer's order, fill it, and take payment.

    This is fine if you have a small number of customers or very simple orders like coffee and doughnuts. But what happens when there is a packed house full of customers, each of whom is ordering a complicated drink (venti mocha, two Splenda, half 2%, half soy...)?
    If each of your employees has to take one order, fill the order, and take payment, before they can serve the next customer, you will need a lot of employees and a very, very big shop! Otherwise, potential customers will be frustrated with the wait, and they will leave.
    This is how many hosts deal with more traffic: they just buy lots and lots of hardware.
  • event based

    The Event-Based Coffee Shop

    One employee takes the orders and delegates them to other employees to fill.

    The ideal solution is to make your employees event-driven: to have one person take the orders and have other people in the background filling those orders. The person taking the orders is concerned only with relaying instructions to the baristas on the backend. In this way, one person can do the work of many. You don't need extra counter space, or many people taking orders.
    This solution scales well. You save money on retail space and wages, and your customers get their fancy coffees more quickly.
    In the same way, LiteSpeed Web Server saves you money on hardware and support by requiring less CPU and less memory, and making your servers run more smoothly.

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Privacy Policy

Privacy Policy

LiteSpeed Technologies, Inc. (aka “LiteSpeed”) is committed to protecting your privacy. This policy ("Privacy Policy" or "Policy") explains our practices for our site, ("Site"). You can visit most pages of the Site without giving us any information about yourself, but sometimes we do need information to provide services that you request. By using this Site or any products or services provided through the Site, you expressly consent to the use and disclosure of information as described in this Privacy Policy.

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Collection of Information

Personal Information.

LiteSpeed will ask you for certain “Personal Information” when you complete registration or product information request forms on the Site, including but not limited to your name, address, telephone number, email address, and credit card information. You can always choose not to provide us with the requested information, however, you may not be able to complete the transaction or use our products or services if you do not provide the information requested.

Non-Personal Information.

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User Communications.

If you communicate with us, we may collect information relating to that communication whether it takes the form of email, fax, letter, forum posting, blog comments, testimonials or any other form of communication between you and LiteSpeed or Submitted by you to the Site (collectively, “User Communications”).

Server Information.

If you use one of our software products such as LiteSpeed Web Server or LiteSpeed Web ADC, we may collect certain information concerning such software and concerning the server upon which the software operates. This information includes: (a) the licensed or unlicensed status of the software; (b) the source from which the license for the software was obtained (i.e., LiteSpeed or a LiteSpeed affiliate); or (c) information about the server upon which the software is installed including (i) the public IP address, (ii) the operating system and (iii) the use of any virtualization technologies on such server ((a) through (c) collectively, “Server Information”). Additionally, “Server Information” may also include information collected from you by LiteSpeed in the event that you request technical support services including without limitation, IP addresses, usernames, and passwords necessary to login to SSH, the root directory of the server upon which you installed the LiteSpeed software and any affected accounts including email accounts, control panel accounts, MySQL accounts, CMS accounts and other accounts.

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We may use User Communications in the same ways we use Personal Information. If you communicate with us for a particular purpose, we may use your User Communications for that purpose. For example, if you contact us for technical support, we may use your communications to provide technical support to you. We may maintain records of User Communications you transmit to us indefinitely, unless otherwise requested as outlined below.

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We may use Server Information to provide you with technical support services and to maintain, evaluate, improve and provide LiteSpeed products and services. We may also use such information to investigate unlicensed (and therefore unauthorized) uses of our software. LiteSpeed may maintain Server Information indefinitely, with the exception of usernames, passwords, and other login information given in connection with support service requests. Such login information will be purged when the ticket is closed.

Disclosure of Collected Information

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You will receive notice in the form of modifications to this Policy when information about you might go to third parties other than as described in this Policy, and you always have the opportunity to contact us as set forth below if you do not wish your information to go to third parties.

LiteSpeed cannot be responsible for protecting your information if you share such information in publicly available sections of the Site such as the user forums, blog comments, or testimonials section. You should use your own judgment in disclosing this information on the Site.

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We use reasonable security methods to protect your personal information from unauthorized access, use or disclosure. No data transmission over the Internet or any wireless network can be guaranteed to be perfectly secure. While we try to protect your personal information, we cannot guarantee the security of any information you transmit to us, and you do so at your own risk.

LiteSpeed uses industry-standard SSL-encryption to protect sensitive data.

In the event that LiteSpeed becomes aware of a security breach, unauthorized disclosure or inadvertent disclosure concerning your information, you agree that LiteSpeed may notify you of such an event using the Personal Information previously provided.

You are responsible for maintaining your account’s security.

GDPR Statement

LiteSpeed Technologies values your users’ privacy. Although our software does not directly collect any personally identifiable information from visitors to your site, LiteSpeed may still be considered a data processor, as user information may be temporarily cached and/or logged, as outlined in this document.


LiteSpeed Web Server, OpenLiteSpeed, LiteSpeed Web ADC, and related software may record IP addresses as a part of normal logging. An access log and an error log may record visitor IP addresses and URL visited. The logs are stored locally on the system where LiteSpeed server software is installed and are not transferred to or accessed by LiteSpeed employees in any way, except as necessary in providing routine technical support if you request it. This logging may be turned off through configuration. It is up to individual server administrators to come up with their own schedule for removing such logs from the file system.

Cache Solutions

Our cache plugins potentially store a duplicate copy of every web page on display on your site. The pages are stored locally on the system where LiteSpeed server software is installed and are not transferred to or accessed by LiteSpeed employees in any way, except as necessary in providing routine technical support if you request it. All cache files are temporary, and may easily be purged before their natural expiration, if necessary, via a Purge All command. It is up to individual site administrators to come up with their own cache expiration rules.

LSCache for WordPress

In addition to caching, our WordPress plugin has an Image Optimization feature. When optimization is requested, images are transmitted to a remote LiteSpeed server, processed, and then transmitted back for use on your site. LiteSpeed keeps copies of optimized images for 7 days (in case of network stability issues) and then permanently deletes them.

Similarly, the WordPress plugin has a Reporting feature whereby a site owner can transmit an environment report to our server so that we may better provide technical support.

Neither of these features collects any visitor data. Only server and site data is involved.

Support Services

Sometimes, when you request technical support, LiteSpeed may ask for login credentials to various areas of your site. You may refuse to share such credentials, however refusal may impact LiteSpeed’s ability to provide the requested support services.

Upon completion of a support ticket, LiteSpeed immediately deletes all login credentials you may have shared.

Any user data encountered by LiteSpeed is kept strictly confidential. We never provide your support ticket information to any third party without your explicit consent.

Contact Us

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