iJUG-Magazin Java aktuell – High Performance Java

Java Aktuell Cover Issue 2/2020
Java aktuell 2/2020

After our presentation at the JUG Saxony Day in 2019, we have been asked to turn the talk into an article for the iJUG-Magazin Java aktuell. The February 2020 issue just got published and features this article. So get yourself the latest Java Aktuell or, if you just want to check out the article, use this link to the PDF and enjoy. The article is in German.

High Performance Java – Hinter den Kulissen von Java

Die Zeiten, in denen Java der langsame Bytecode-Interpreter war, sind lange vorbei. Die JVM nutzt viele Tricks, um Code effizient auszuführen, und transformiert und optimiert Java-Code auf die ausführende Hardware. Mit etwas Wissen über diese Prozesse kann man vermeiden, dass man gegen die JVM arbeitet, und gleichzeitig mehr Geschwindigkeit erreichen. Selbst wenn man nicht die letzte Mikrosekunde jagt, ist es interessant zu sehen, welche Techniken die JVM einsetzt, um die Ausführungsumgebung besser zu verstehen.

Comments are very welcome.

BOM – Byte Order Mark

Because we encountered another hidden encoding issue as part of test data, here are some information about BOM and why this might be interesting in general for everyone working with a computer beyond Excel and Word.

Before you educate yourself, here is the tool to own to see such a problem easily. Most of all editors hide that information and so you might scratch your head why some data is failing with strange error messages. Get xxd and you will see with other eyes:

xxd /tmp/2018-01.csv 
0000000: efbb bf23 4375 7374 6f6d 6572 204e 756d  ...#Customer Num
0000010: 6265 722c 5265 6164 204f 6e2c 506f 7765  ber,Read On,Powe
0000020: 7220 4d65 7465 7220 5265 6164 696e 670d  r Meter Reading.
0000030: 0a30 3030 312c 3230 3138 2d30 352d 3032  .0001,2018-05-02
0000040: 2c35 3030 0d0a                           ,500..

The first marked bytes are the magic and now head over to the Wikipedia to read more about BOM: https://en.wikipedia.org/wiki/Byte_order_mark

Thuringia’s Open-Source Prize for XLT

Wolfgang Tiefensee, Thuringia’s Secretary of Commerce, in conjunction with the board of directors of the IT industry network ITNet Thuringia, awarded the first Thueringen Open-Source Prize to three companies, all of them software companies based in Jena: TRITUM, Xceptance and GraphDefined.

Open Source Prize Title Picture Second Place

It is an honor for Xceptance to be the second-place winner of this competition. This result clearly demonstrates that open source as a component of commercial products can be a clear competitive advantage. XLT incorporates a number of open-source projects, including Apache HttpClient, Jetty, HtmlUnit, JUnit, and the Apache Commons libraries. As part of developing XLT, Xceptance is involved in testing and providing feedback for these projects, thus giving back to the open-source community.

While XLT is itself not open source, Xceptance does provide the software free of charge and with virtually no usage restrictions, so for most applications there is no noticeable difference to open-source software.

Comparing Measured and Perceived Loading Times

TL;DR: The perceived loading time is what shapes the user’s impression of the speed of a website, but measuring perceived loading time is difficult. There are technical loading times available but it is not clear if these times can be used in any meaningful way. This master’s thesis verified whether the perceived loading time can be easily correlated with any technical loading time, such as FirstPaint for instance. The result shows that a page with a fast loading time from a technical point of view is not necessarily perceived as fast by the user and vice versa. Therefore it is not sufficient to rely only on technical measurements and disregard the user’s perception.

Client-side performance is a big deal. There are various studies on the relationship between loading time and critical success factors such as usability of online shops, customer loyalty and sales. Yet a page with an objectively long total loading time could still be perceived as fast by the user, as the visible part of the browser window has already loaded and invites the shopper to interact with the page.

In her master’s thesis “Client-side performance: Comparison of measured and perceived loading times of online platforms in the B2C sector” Bastienne Sauter scientifically evaluated this discrepancy between the technically measured and the perceived loading times. By implementing automated tests with the automation tool XLT (Xceptance LoadTest), the loading times (timestamps recorded: domLoading, firstPaint, domInteractive, domContentLoadedEventStart, domContentLoadedEventEnd, domComplete, loadEventStart and loadEventEnd) of fifteen German e-commerce stores were measured over a longer period of time, both for desktop and mobile. For each store and timestamp, a ranking of the average loading times was calculated for each device.

In order to determine the empirical values for the perceived loading time, an interaction study with test groups of students and of Xceptance employees was conducted. Each group consisted of 25 persons, so a total of 50 people took part in the study. The participants had to open predefined pages of an online store and assess the loading impression. The user’s perception was evaluated using suitable scales. In this manner a score value was determined for each store among the two test groups. Each participant evaluated only three of the 15 stores in order to keep the effort manageable. In other words a store was covered by five test persons of each group (according to Nielsen and Landauer, a total of five respondents per store is sufficient for usability tests to be meaningful and to cover the majority of usability results). To ensure comparability of the results, the interaction study was conducted on the same devices and at the same location to avoid different bandwidths of the internet connection. Furthermore the test session for every person was set up in a way to avoid stress and create a normal daily usage situation.

Comparing the measured technical loading times with the perceived ones from the study, it showed that they differ clearly from each other, with no significant correlation.

To get an impression of which timestamp could be most relevant for the perceived loading time, the distances of the positions in the rankings were calculated. The smallest deviations for the desktop showed the timestamp domContentLoadedEventEnd, while the timestamp firstPaint could be most relevant for mobile devices.

Sum of the distances between the different positions in the rankings
Sum of the distances between the different positions in the rankings

As a conclusion, it is neither sufficient nor purposeful to consider only the technical measurements for the evaluation of the client-side performance, because the user’s perception deviates significantly from the technical measurement. This proved to be true both for informed insiders (represented by company employees) and also the uninformed public (represented by the students).

The results raise further research questions, especially how quality key figures for the perceived loading time can be recorded and contribute to the evaluation of online stores. In the literature, user-centered key figures such as FirstMeaningfulPaint are cited for this purpose. Whether these figures are in fact useful to represent the perceived loading time, however, is unclear and requires further investigation.

Illustration of Load Metrics by Google under CC-BY-3.0 

XLT 4.12.2 Release

Xceptance released version 4.12.2 of its load testing and test automation product Xceptance LoadTest. This is an improvement release. We recommend upgrading to this newest version.

Test Framework

  • Improvement: The result browser features a new tab that displays JSON responses in a tree-like view. The data can also be searched and filtered.
  • Improvement: The existing automatic request retry mechanism has been enhanced to retry failed requests in additional error situations such as connection resets. This should now behave similar to real browsers.
  • Improvement: When failed requests are retried, an event with diagnostic information is logged for each retry.
  • Improvement: The bundled Jetty library has been updated to the latest available version 9.4.14.

Load Testing

  • Improvement:  Our public AWS machine images now come with OpenJDK 11.

Make sure to read the full online release notes.

As always, this upgrade is free and don’t forget, XLT itself is free as well. You don’t have an excuse to skip performance testing or rely on lame simple test cases anymore.

XLT 4.12.1 Release

Xceptance has released version 4.12.1 of its load testing and test automation product Xceptance LoadTest.

Test Framework

  • Fix: Our timer recorder extensions for Chrome and Firefox did sometimes report invalid request entries that could not be processed by the report generator. This could happen for requests that did not complete.
  • Fix: If a test case deliberately caught an exception / assertion error and afterwards ran to completion successfully, it might nevertheless be marked as failed in the load test report.
  • Improvement: Selenium has been updated to the latest version 3.141.59 and HtmlUnitDriver to version 2.33.3.

Load Testing

  • Improvement: The new AWS data center in Stockholm, Sweden (eu-north-1) is fully supported by ec2_admin now.

Make sure to read the full online release notes.

As always, this upgrade is free and don’t forget, XLT itself is free as well. You don’t have an excuse to skip performance testing or rely on lame simple test cases anymore.

XLT 4.11 was released

Xceptance released version 4.11 of its load testing and test automation product Xceptance LoadTest. This is a feature release. We recommend upgrading to this newest version.

Here is a selection of the most important changes:

  • HtmlUnit and Selenium have been updated
  • You can run a test case with only a single data set at development time
  • XLT picks a data set automatically when a test with multiple data sets is part of a load test
  • There is a new command-line tool to automatically evaluate a test report based on your defined success criteria
  • The XLT Jenkins plugin returns a result object now with all the details when used in a pipeline
  • The XLT Jenkins plugin can now create a comparison report

See our release notes for more details. As always, this upgrade is free and don’t forget, XLT itself is free as well. You don’t have an excuse to skip performance testing or rely on lame simple test cases anymore.

XLT – Now Available Free Of Charge

Update: Please see Xceptance LoadTest Goes Open Source for the next step in the evolution of XLT.

Because it is always great to end the year with something pleasant and start the next year with something even better, we want to surprise you with the announcement that Xceptance LoadTest (XLT) will be free of charge for load and performance testing starting 1 January 2018. XLT was already free for use in test automation.

Why are we doing this? Well, we have seen many people working with other performance test tools over the years and found that often they chose one primarily because of the price or simply because it was already a familiar tool in the company. This is not necessarily bad but it is certainly not always optimal.

People run into seat limits, operating system limitations, debugging limits, extensibility limits, have to use poor reporting, or cannot adjust features or functionalities. We want to give the testing world a tool that will be chosen because it fits and not because the license is cheaper or has already been purchased. Or in other words: You have more choices now.

Xceptance and its customers have been using XLT for many years. What started as a quick workaround because commercial tools had no affordable license a consulting company could use, grew into a versatile tool with a focus on great reporting and diagnostic capabilities.

We will update the license portal to the new model in the next few days and also rework our website accordingly. We just didn’t want to wait to tell our existing customers and take one worry off the 2018 budget table.

Happy Holidays, Merry Christmas, and a Happy New Year!

New Free-License Terms

Obviously some context is needed to make clearer what you can do with XLT and its free-of-charge license now.

  • XLT is available free of charge but you still need a license file from us. Request this license from Xceptance via email (support@xceptance.de) or use our license portal, and we will issue you one without any user or time limits.
  • You can use XLT for commercial purposes as long as you do not sell XLT itself or create the impression that XLT is your own software. You can sell software components built on top of XLT.
  • You must not modify XLT in any way. But you can customize test suites, demos, templates, or other customizable components such as CSS or XSL as long as you distribute these components separately.
  • You cannot offer XLT for download, excluding your local Maven/Nexus repositories and company internal redistribution, of course.
  • You cannot integrate XLT into public SaaS or other commercial or noncommercial hosting offers without explicit permission from us. If you built your own company-internal cloud for load testing for instance, that is of course permitted.
  • You cannot share your license outside of your organization. If you are a consulting company or freelancer, we encourage your clients to request their own licenses, but we do not require it. All licenses are personalized with email and company name.

FAQ

Is XLT open source now?

No, XLT is still closed source; we just stopped charging you for using it.

Will updates be free, too?

Yes, updates stay free. Please make sure you sign up for our release newsletter. Purchasing a support contract allows us to support you faster and more directly.

Can I use XLT commercially?

Yes, you can. Just request a license. If you are not sure whether your usage pattern is covered by our free-license terms, please ask. If you have interesting business ideas or applications for XLT, we are here to help.

Will Xceptance continue to invest in XLT?

Yes, we will continue to invest in and enhance XLT because it is an integral part of our company’s load and performance testing services. Product development is funded by the support, training, and testing services provided by Xceptance.

Firefox 57 Changes and XLT

Firefox 57 is going to deliver a fundamental change that will affect XLT Script Developer.

As you might know, Mozilla decided to completely remove the support for XUL/XPCOM-based extensions (aka legacy extensions) in favor of extensions built upon the WebExtension API. This cut will take place on November 14, 2017, with the release of Firefox 57. Additionally, Mozilla will refuse to sign updates of legacy extensions at some point in the near future, although the exact date is not determined yet. See the Mozilla Add-ons Blog for an up-to-date timeline.

The consequence of this breaking change is that XLT Script Developer cannot be installed in Firefox 57 and higher. Also, an already installed XLT Script Developer cannot be used any longer.

We at Xceptance have been aware of this development. Over the course of the last year we have been busy evaluating several alternative options. As you might recall, we also conducted a survey back in the spring to collect your feedback.

Based on our findings and your input and after long discussions, we came to the conclusion that the feature set and comfort that had been offered by XLT Script Developer and its way of writing web automation cannot be recreated using the alternative Firefox APIs.

Therefore, we regret to announce that Script Developer is discontinued. Consequently, we don’t recommend starting new test projects based on Script Developer and XML script test cases. To be able to continue to use the features of XLT and the advantages it offers, we suggest you use XLT’s Java-based API.

If you are able to use Firefox 56 or Firefox 52/ESR, maybe in parallel to an updated version of Firefox, you can continue to work with XLT Script Developer as well as execute all your test cases as you have been.

We are aware that this decision might disappoint many of you and may leave open questions. For more information on what shaped this decision and what your options are for maintaining your existing XML script test suites in the future or migrating them to another base, please see the Q&A section below.

Q&A

Why did Mozilla decide to abandon legacy extensions?

By design, legacy extensions have not only full access to your local file system but also to the entire browser and thus to all the pages you visit. This has been causing privacy and security issues and hence Mozilla decided to abandon the API to address these problems.

Why isn’t XLT Script Developer being ported to the WebExtension API?

The possibilities offered by the WebExtension API are very limited. One such limitation, and the most important one, is that access to the local file system involves a user interaction for each and every file to save or read. This would make Script Developer simply impossible to use.

Further restrictions apply. Most of them are related to accessing and manipulating session and browsing data such as cookies or cache. In the end, Script Developer would only be able to support a very reduced feature set.

And last but not least, the outcome of our customer survey revealed needs which cannot be met by such a modest visual, non-programming approach to writing tests. See the next question for more details on the feedback we received.

Why won’t XLT Script Developer be ported to another platform?

The outcome of our survey was that users wanted a tighter integration with Java/IDEs, more commands, more ways to customize things, better flow control, and more flexibility with test data. At the end of the day, this is a full programming approach and turning the XLT Script Developer into another programming environment couldn’t address all these points.

We also believe that the concept of XML script test cases with their limited capabilities are no longer appropriate for modern testing needs. Therefore we have decided to give it up in favor of the opportunities a real programming language provides.

Can I continue to use XLT Script Developer with Firefox 56?

Yes, but at your own risk. Remember that your browser cannot be updated and therefore will not receive any security fixes. Furthermore, it may not be possible to install any Script Developer updates as this Firefox version accepts signed extensions only. And Mozilla might stop signing legacy extensions any day. See below for a better solution.

Can I continue to use XLT Script Developer with Firefox 52/ESR?

Yes, absolutely. That is the recommended way to go, at least for the next months. First, Firefox 52/ESR (Extended Service Release) will be updated with security fixes until May 2018. If you continue to use Script Developer after that date, though, you do so at your own risk. Make sure that you use this browser version for scripting only.

Furthermore, Firefox 52/ESR can be tweaked to install legacy extensions even if they are not signed by Mozilla. This way, you are still able to install Script Developer updates in case Xceptance provides some in the future.

Will the XLT framework still be able to replay XML script test cases?

Yes, XLT will continue to interpret and execute your existing XML script test cases as JUnit tests via their wrapper classes.

How to migrate existing projects?

Export all your existing XML script test cases to Java (Scripting API). From this point, you maintain your test cases in your favorite Java IDE instead of the XLT Script Developer. Since the concepts and commands are the same as in Script Developer, you will be on top of things quickly.

Instead of running your XML test cases in Script Developer, you would now run your Java-based tests as JUnit tests using your preferred WebDriver either from your IDE or using a continuous integration system.

Since your code base is plain Java now, you are free to add all the things that you might have missed in the past.

Note that XLT 4.10.0 will ship with some enhancements for Java-based test cases. For instance, Script Developer will provide an alternative export template that produces more compact code. Additionally, writing test cases directly in Java will be more comfortable as well. Stay tuned for the upcoming release and find all the details in the release notes.

Make sure you subscribe to our low-volume XLT release and news mailing list.

How long will you release XLT Script Developer updates?

TBD. Future updates of Script Developer will be bug-fix releases only (shipped as unsigned extensions once Mozilla stops signing legacy extensions). Don’t expect any new features.

Are there any other options?

Yes. There are forks of Firefox that promise to continue supporting legacy extensions while being kept up-to-date at the same time. For instance, Script Developer installs and runs nicely in Waterfox. However, we cannot predict how long this will actually work.