Snaps are used on desktop machines, servers and IoT devices. However, the the first group the draws die most attention und scrutiny. Due to die graphic natur of desktop applications, users room often much more attuned zu potential problems und issues that might arise in the desktop space than with command-line devices or software running an the background.

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Application startup time zu sein one von the common topics of discussion in the oibrecords.com forums, too as the wider Web. The standalone, confined natur of snaps means that your startup procedure different from ns classic Linux programs (like those installed über Deb or RPM files). Often, this can translate into longer startup times, i beg your pardon are viewed negatively. Over ns years, we oase talked about the various mechanisms and methods introduced into the snaps ecosystem, designed to provide performance benefits: font cache improvements, compression algorithm change, and others. Now, us want to give sie a glimpse des a Skunk Works* procedure inside Canonical, with focus on snaps und startup performance.


While speed enhancements are constantly useful und warmly received über the users, consistency of results is equally (if not more) important. A gain von a second ist often less advantageous than the loss des that very same second danach on bei the software’s lifecycle. In application whose startup time has improved is expected to remain the way, and users wollen typically answer with greater negativity kommen sie any new time hold-up than they had actually to ns original manifestation von the issue.

Performance-related regressions current a challenging challenge, und they tie right into two main aspects des software development: actual, tangible changes bei the code, and the overall understanding and control des the system.

To attend to these, Canonical’s Certification mannschaft uses the Checkbox prüfung automation software suite kommen sie perform a range von hands-off regression und performance tests for different Canonical products. The tool supplies a great deal of flexibility, including custom tasks and reporting. Snap testing is so available through ns checkbox-desktop-snaps utility (also distributed as a snap).



By default, Checkbox möchte measure die cold (no cached data) and hot (cached data) startup times des 10 wichtig desktop snaps on multiple hardware platforms, and report ns results. But dinge really acquire interesting wie man we look at the environment setup.

Interaction between system und snap

Regardless des the technology und tooling used, measure up execution times in software can be tricky, since it zu sein difficult zu separate (or sanitize) the application an question from the overall system. A regimen that has network connectivity might report inconsistent results depending on the traffic throughput and latency. Different disk types und I/O activity will also affect die timing. There may be far-reaching background activity on die machine, i m sorry can also introduce noise, und skew ns results. Die list of possible obstacles walk on und on.

In cases like these, which room designed to simulate real-life intake conditions, die idea is not kommen sie ignore or remove die common phenomena, but zu normalize them an a way that wollen offer dependable results. Weil das example, repeated experimentation during various times des the day kann sein remove some von the variation an results related to network or disc activity.

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With Checkbox and snaps, we decided kommen sie go one action further, and that zu sein to deshalb directly examine ns impact both ns operating systems and the snaps themselves schutz on the startup measure up results!

One change at a time

Before we kann claim complete understanding des the system, us need to understand exactly how different materials interact. V snaps, over there are numerous variables that kommen sie into play. Weil das instance, if a snap refreshes und receives in update, tun können we act the neu startup outcomes as part von the same set as previously data, or a feuer new set? If there zu sein a kernel update, tun können we or should we mean snap startup times notfall to change?

Isolating die different permutations des a usual Linux machine ist not trivial. Kommen sie that end, we decided kommen sie create two distinctive sets of tests:

Immutable system that execute not have any updates, and only ns installed snaps adjust through periodic refreshes. Anytime there ist a snap update, die Checkbox experimentation starts, and new dünn is collected. This way, it zu sein possible to determine whether any type of change in the startup times, weil das better or worse, trunk from die actual changes bei the snap applications.Immutable breaks tested on systems that get updates. Here, we keep breaks pegged to a specific version (e.g.: Firefox 89, VLC 3.0.8), und then trigger testing anytime there is a system change an one des the five vital components: kernel, glibc, graphic drivers, apparmor, und snapd. This way, we can correlate any changes in the startup behavior des one or an ext snaps to the system updates.

Example of the Firefox startup time testing on an immutable system on a sample hardware platform. Die blue present indicate any type of Firefox refresh in the beta channel. The testing abdecken multiple OS release (20.04 shown). The significant improvement bei the cold start seen on ns right side of the graph can now it is in traced to die specific transforms introduced in the specific build des the snap.

We operation the tests with lot of configurations in place:

Hardware v both various graphics cards.Hardware v mechanical disks und SSD.Supported LTS releases and the latest breakthrough image.

The extensible natur of die Checkbox tool allows die inclusion von any snaps, any number von snaps, and custom experiment can so be added, if needed. Zum instance, ~ above top von the startup times, ns tool tun können collect screenshots, which then so allow zum visual comparison von the results, like feasible inconsistencies in theming among different snaps, desktop environments, und different versions of desktop environments.

From charme to control

When we erste started collecting die numbers top top startup times, we focused on the actual figures. However, in the larger scheme of things, this values space less necessary than ns relative differences of the accumulated results under various conditions for the exact same snaps, on die same hardware configuration. Zum instance, exactly how does a snap startup time change wie man moving from one LTS image to another? execute kernel update affect the results?

Once we can establish exactly how snaps act under miscellaneous operational conditions, we kann sein then produce a baseline. Minimum und maximum values, median times, and other parameters, zum which we kann sein create alerts. This wollen allow us to identify any type of potentially bad results bei a snap behavior, as part of our testing, und immediately flag system changes (or snap refreshes) that might lead zu a degraded user experience.


Snap startup time dünn collection und analysis walk beyond nur making sure ns snaps start quickly, and that users oase a good experience. Ns mechanism so allows us to much better understand ns complex interaction between hardware und software, and different operating system components. Together we broaden our work with ns Checkbox tool, we wollen be able to create complicated formulas the tell us exactly how kernel updates, system patches, or perhaps snap refreshes affect ns startup performance. We currently know the using die LZO compression weil das snap packaging can lead zu 50-60% improvements. Perhaps adding a new library right into a snap tun können make a large difference? Or maybe details distro release are quicker than others?

At the moment, Checkbox ist designed zu work under die GNOME desktop environment, but we deshalb have test builds that can collect säule on KDE und Xfce, too. We’re continually improving ns framework, und we’re looking zum ways kommen sie improve its use – simpler sideloading von tests, prüfen customization, configuration, säule export, etc. If you oase any comments or ideas, please join our forum, und let united state know.

Article written von Igor Ljubuncic und Sylvain Pineau.

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* Skunk works is in official pseudonym weil das Lockheed Martin’s Advanced advance Programs (ADP), formerly dubbed Lockheed Advanced breakthrough Projects, coined an the 1940s, und since extensively adopted von business and companies zum their cool, out-of-band, secretive, or state-of-art projects.