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SEARCH KEYWORD -- System

  How to write good requirements

Requirements are pretty ubiquitous in the embedded world. They are used to define tasks, help coordinate large development efforts, and to communicate the behavior of the desired end product between the developers and the customer. When done right, requirements can be very useful. Unfortunately, if you spend much time working in the embedded world you quickly discover that there are a lot of bad requirements. And then when you try to go fix them, you quickly discover that writing good req...

   Requirement gathering,Good requirement     2012-02-18 12:53:15

  How Kafka achieves high throughput low latency

Kafka is a message streaming system with high throughput and low latency. It is widely adopted in lots of big companies. A well configured Kafka cluster can achieve super high throughput with millions of concurrent writes. How Kafka can achieve this? This post will try to explain some technologies used by Kafka. Page cache + Disk sequential write Every time when Kafka receives a record, it will write it to disk file eventually. But if it writes to disk every time it receives a record, it would ...

   BIG DATA,KAFKA     2019-03-08 09:42:57

  Mount DD image on Linux

Yesterday, my Raspberry Pi running Arch Linux was not able to boot with error: Kernel Panic, not syncing: no init found. I spent a night on it, but could not find a working solution. The last option is easy: reinstall the system. That is really the last resort, for I do not want to re-setup everything I have done: samba server, Time Machine server, Xunlei Offline Downloader… Unable to mount the SD card The system does not boot, so I need to find a way to get into the file system to identi...

   LINUX,DD IMAGE     2014-06-24 07:49:14

  Android 4.0+ occupies quarter of Android market

Google updates its developer page about Android platform version market share. From the latest data, we can find Android 4.0 and above system occupy around 25% of all Android market. But Android 2.3 Gingerbread still occupies over 50% of Android market. From the above chart, Android 4.0 has 23.7% market share, the latest Android 4.1 JellyBean takes 1.8%, these two have 25.5% market share in total. But Android 2.3 Gingerbread alone still dominates the Android market, it takes 55.8% market share....

   Google,Android,Share     2012-10-02 19:22:19

  Check file readability in Java

File operation is quite platform dependent. Although Java is a cross platform programming language, the file operation in Java is also platform dependent. The obvious evidence is the file permission check. In Java, we can call canRead(), canWrite() and canExecutable() to check whether the program can read, write or execute the file specified. However, on Windows, when we call canRead() on a File object, we may get unexpected result. Actually, on Windows, when we call canRead() on a File object, ...

   Java,Files,Readable,Check     2013-12-05 06:10:15

  Use Java ThreadLocal with caution

According to Oracle documentation, ThreadLocal is a class provides thread-local variables. These variables differ from their normal counterparts in that each thread that accesses one (via its get or set method) has its own, independently initialized copy of the variable. ThreadLocal instances are typically private static fields in classes that wish to associate state with a thread. In short, ThreadLocal variables are variables belong to a thread, not a class or an instance of a class. One common...

   JAVA,MEMORY LEAK, THREADLOCAL     2015-11-03 07:31:57

  Google's new pirate penalty doesn't affect YouTube

Google has just announced a new policy: sites with high numbers of removal notices may appear lower in our results. However, this new policy may not affect the company's video site YouTube. In fact, they themselves clearly know that there are copyright protected contents on YouTube.According to a report published by Search Engine Land, through the "Removing Content From Google" page, users can remove content from the Google services with valid reasons, the services including Google Play, Google+...

   Google,Privacy,YouTube,Rank     2012-08-12 12:35:29

  Hadoop or Spark: Which One is Better?

What is Hadoop? Hadoop is one of the widely used Apache-based frameworks for big data analysis. It allows distributed processing of large data set over the computer clusters. Its scalable feature leverages the power of one to thousands of system for computing and storage purpose. A complete Hadoop framework comprised of various modules such as: Hadoop Yet Another Resource Negotiator (YARN MapReduce (Distributed processing engine) Hadoop Distributed File System (HDFS) Hadoop Common Thes...

   COMPARISON,HADOOP,SPARK     2018-11-22 07:08:57

  How to enable developer mode on Huawei

As a developer, there might be some need to fake locations when developing and testing mobile apps for different countries. Lots of the times some fake GPS apps will be used and they will ask to enable mock location access on the device before allowing you to fake GPS. To achieve this, we first need to have developer mode enabled. In this post, we will show how the developer mode can be enabled and disabled on Huawei devices. Go to Settings, find About phone and open it. You should be able to se...

   ANDROID,HUAWEI,DEVELOPER MODE,DEVELOPER OPTIONS     2020-08-15 21:22:29

  Java Concurrency Basics: CountDownLatch and CyclicBarrier

CountDownLatch CountDownLatch can be used in synchronizing behavior among threads, it makes one or more threads wait for some actions in other threads to be completed. It has a property count which defines how many countDown() need to be called before other threads which called await() to be waked up.  When a thread calls CountDownLatch.await(), the thread will be blocked until the value of count becomes 0. The initial value of count can be specified when creating the CountDownLatch instanc...

   JAVA,JAVA CONCURRENCY,COUNTDOWNLATCH,CYCLICBARRIER     2018-03-25 07:02:40

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