Tutorials/Tips

Systemd for Developers

Systemd not only brings improvements for administrators and users, it also brings a (small) number of new APIs with it. In this blog story (which might become the first of a series) I hope to shed some light on one of the most important new APIs in systemd:

Socket Activation – In the original blog story about systemd I tried to explain why socket activation is a wonderful technology to spawn services. Let’s reiterate the background here a bit.

The basic idea of socket activation is not new. The inetd superserver was a standard component of most Linux and Unix systems since time began: instead of spawning all local Internet services already at boot, the superserver would listen on behalf of the services and whenever a connection would come in an instance of the respective service would be spawned.

Related Post:  Accessing Bingo Sites through Linux

This allowed relatively weak machines with few resources to offer a big variety of services at the same time. However it quickly got a reputation for being somewhat slow: since daemons would be spawned for each incoming connection a lot of time was spent on forking and initialization of the services — once for each connection, instead of once for them all.

Related Post:  How to install Apache web server on Fedora

Spawning one instance per connection was how inetd was primarily used, even though inetd actually understood another mode: on the first incoming connection it would notice this via poll() (or select()) and spawn a single instance for all future connections. (This was controllable with the wait/nowait options.)

That way the first connection would be slow to set up, but subsequent ones would be as fast as with a standalone service. In this mode inetd would work in a true on-demand mode: a service would be made available lazily when it was required. Continue reading…

Subscribe to LinuxBSDos.com

Subscribe to receive the latest articles in your Inbox

Trust me, you'll not be spammed...

Please share:
Tags:

We Recommend These Vendors and Free Offers

Google has got competition, because Presearch is building a blockchain-based search engine controlled by the community. At $0.15 a token, you can participation in Lot 3 of the token sale by clicking here

Open Money is building a solution that will run mainstream software on blockchain tech. Click here to get free tokens that will be the digital currency of the platform

COMSA allows centralized businesses to adopt blockchain technology. The token sale starts soon! Sign up for free by clicking here

Register now for Blockchain & Cryptocurrency Con 2018, international conference on blockchain technnology in Dallas, TX (USA), Feb. 23-24, 2018. Students can register at a 50% discount.

Launch an SSD VPS in Europe, USA, Asia & Australia on Vultr's KVM-based Cloud platform starting at $5:00/month (15 GB SSD, 768 MB of RAM).


Leave a Comment

Your email address will not be published. Required fields are marked *

*