• How HealthTech Startups Are Leveraging Tech To Combat COVID19?

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      Source: Google Images

      The world has taken aback through the global pandemic of Novel Coronavirus or Covid19. With the spontaneous outbreak of the coronavirus pandemic worldwide, most of us are self-quarantined and taking precautionary measures. The situation is further amplified with an ongoing economic slowdown.

      However, our healthcare industries, startups and front-line medical professionals & staff haven't taken a step back in dealing with the pandemic through innovative healthcare measures that can effectively combat and procure ailing patients from Coronavirus outbreak.
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    • Active Restore: Can we Recover Faster? Much Faster?

      • Translation
      Backing up valuable data is a proven practice, but what if we need to continue work immediately after a natural disaster or other disruptive events, and every minute is important? Our team at Acronis decided to see how quickly we can start an operating system. This is our first post from the Active Restore series. Today I will tell you how we launched our project with Innopolis University, which solutions were studied, and what we are working on today. All the details are under the Cut.

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    • Android 11: What to Expect From the Latest Android Update?

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        Source: Google Images

        The latest Android 10 update has already created a stir in the Android circuit. However, tech enthusiasts around the world are waiting for the latest addition in Android's operating system.

        Yes, you heard it right, I am talking about the Android 11 update, the latest upgrade in the Android’s operating system.

        The update has been expected to hit the floors in the official reveal of Android 11 in mid-2020, at Google IO 2020 which will run May 12-14, before being released for Pixel devices in the month of September, and then it will be rolled out for other Android devices from late 2020 through well into 2021.
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      • How does strange code hide errors? TensorFlow.NET Analysis

          PVS-Studio and TensorFlow.NET

          Static analysis is an extremely useful tool for any developer, as it helps to find in time not only errors, but also suspicious and strange code fragments that may cause bewilderment of programmers who will have to work with it in the future. This idea will be demonstrated by the analysis of the TensorFlow.NET open C# project, developed for working with the popular TensorFlow machine learning library.
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        • No-code: yesterday, today, tomorrow

          No-code movement is a new approach to website and app development. It doesn't require technical knowledge. Does no-code movement have something in common with old image boards, guest books and creation of MySpace or Facebook? Yes, it does. And here is why.

          No-code is a reflection of social tendencies made in technologies. To understand it, we need to discover the history from the beginning of the World Wide Web.
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        • AdBlock has stolen the banner, but banners are not teeth — they will be back

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        • WAL in PostgreSQL: 3. Checkpoint

          • Translation
          We already got acquainted with the structure of the buffer cache — one of the main objects of the shared memory — and concluded that to recover after failure when all the RAM contents get lost, the write-ahead log (WAL) must be maintained.

          The problem yet unaddressed, where we left off last time, is that we are unaware of where to start playing back WAL records during the recovery. To begin from the beginning, as the King from Lewis Caroll's Alice advised, is not an option: it is impossible to keep all the WAL records from the server start — this is potentially both a huge memory size and equally huge duration of the recovery. We need such a point that is gradually moving forward and that we can start the recovery at (and safely remove all the previous WAL records, accordingly). And this is the checkpoint, to be discussed below.

          Checkpoint


          What features must the checkpoint have? We must be sure that all the WAL records starting with the checkpoint will be applied to the pages flushed to disk. If it were not the case, during recovery, we could read from disk a version of the page that is too old, apply the WAL record to it and by doing so, irreversibly hurt the data.
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        • Checking the Code of Zephyr Operating System

            PVS-Studio and Zephyr

            Some time ago we announced PVS-Studio's new feature that enabled it to integrate into PlatformIO. Naturally, our team kept in touch with the PlatformIO team while working on that feature, and they suggested that we check the real-time operating system Zephyr to see if we could find any interesting bugs in its code. We thought it was a good idea, and so here's this article about the check results.
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          • This is how you deal with route leaks

              That, we must say, is the unique story so far.

              Here’s the beginning: for approximately an hour, starting at 19:28 UTC on April 1, 2020, the largest Russian ISP — Rostelecom (AS12389) — was announcing prefixes belonging to prominent internet players: Akamai, Cloudflare, Hetzner, Digital Ocean, Amazon AWS, and other famous names.

              Before the issue was resolved, paths between the largest cloud networks were somewhat disrupted — the Internet blinked. The route leak was distributed quite well through Rascom (AS20764), then Cogent (AS174) and in a couple of minutes through Level3 (AS3356) to the world. The issue suddenly became bad enough that it saturated the route decision-making process for a few Tier-1 ISPs.

              It looked like this:

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              With that:

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            • Juggling work and study at ITMO University: CS edition

                We talked to the graduates of the Speech Information Systems MA program at ITMO about the ways our university helped jumpstart their careers. [More stories from our startups]:


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              • SQL Server & Concurrency Control

                • Tutorial

                What is a Transaction?


                The standard definition of Transaction state that “Every Query batch that runs in a SQL server is a Transaction.”, this means any query you run on a SQL server will be considered as a Transaction it could either be a simple SELECT query or any UPDATE or ALTER query.


                If you run a query without mentioning the BEGIN TRAN keyword then it would be considered as an Implicit transition.


                If you run a query which starts with BEGIN TRAN and ends with COMMIT or ROLLBACK then it would be considered as Explicit Transaction.

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              • How to develop and publish a smart-contract in the Telegram Open Network (TON)

                  What is this article about?


                  In this article, I will tell about my participation in the first (out of two so far) Telegram blockchain contest. I didn't win any prize. However, decided to combine and share the unique experience from the start to finish line, so my observations could help anyone who is interested.


                  Since I didn't want to write some abstract code, instead make something useful. I created instant lottery smart-contract and website which shows smart-contract data directly from Telegram Open Network (TON) avoiding transitional storage.


                  The article will be particularly useful for those, who want to write their first smart-contract in TON but has difficulties where to start.


                  Using the lottery smart-contract as an example, I will show the path from the environment set up till publication of the smart-contract and its interaction. Moreover, I will create a website that will show smart-contract data.

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                • Implementing Fault-Tolerance PostgreSQL Cluster with Patroni

                    I'm a DevOps Teamlead at Miro. Our service is a high-load one: it is used by 4 million users worldwide, daily active users - 168,000. Our servers are hosted by Amazon and located in a single Ireland region. We have more than 200 active servers, with almost 70 of them being database servers.

                    The service's backend is a monolith stateful Java application that maintains a persistent WebSocket connection for each client. When several users collaborate using the same whiteboard, they see changes on the whiteboard in real-time. That's because we write every change to a database, resulting in ~20,000 requests per second to the databases. During peak hours, the data is written to Redis at ~80,000–100,000 RPS.

                    I am going to speak about why it is important to us to maintain PostgreSQL high availability, what methods we've applied to solve the problem, and what results we've achieved so far.

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                  • WAL in PostgreSQL: 2. Write-Ahead Log

                    • Translation
                    Last time we got acquainted with the structure of an important component of the shared memory — the buffer cache. A risk of losing information from RAM is the main reason why we need techniques to recover data after failure. Now we will discuss these techniques.

                    The log


                    Sadly, there's no such thing as miracles: to survive the loss of information in RAM, everything needed must be duly saved to disk (or other nonvolatile media).

                    Therefore, the following was done. Along with changing data, the log of these changes is maintained. When we change something on a page in the buffer cache, we create a record of this change in the log. The record contains the minimum information sufficient to redo the change if the need arises.

                    For this to work, the log record must obligatory get to disk before the changed page gets there. And this explains the name: write-ahead log (WAL).

                    In case of failure, the data on disk appear to be inconsistent: some pages were written earlier, and others later. But WAL remains, which we can read and redo the operations that were performed before the failure but their result was late to reach the disk.
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                  • OpenToonz: inside and out

                      Picture 1

                      Almost four years have passed since the PVS-Studio team checked the OpenToonz source code. This project is a very powerful tool for creating two-dimensional animation. Since the last check, with its help, such animated works as Mary and the Witch Flower, Batman-Ninja, Promare and others were created. As large studios continue using Toonz, why not check the quality of the source code again?
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                    • Signpost: When Breakpoints are not Enough

                      • Tutorial

                      Instruments for Apple's Xcode is a tool for performance analysis of an iOS application. In 2018 Apple introduced Custom Instruments — an opportunity to expand the standard set of instruments for application profiling. When existing tools are not enough, you can create new ones yourself — it will collect, analyze and display the data the way you need.




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