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Sun Mar 29 18:15:44 HKT 2020
From /weblog/java/concurrency
Even though
private List synchList = Collections.synchronizedList(new LinkedList());
is thread safe, serialize sync List is NOT thread safe for sure. The story is, if you only synchronized the collection, and if we try to get the iterator in concurrent access environment, it will throws currencymodificationexception . For collection is small, may be making defensive copy http://www.javapractices.com/Topic15.cjp is good. Otherwise, in java5, there is concurrency collection. reference: http://jroller.com[..]ntry=collections_synchronizedlist_broken http://jroller.com/page/ctarrington?entry=java_collections_trivia Map operation, include use of FutureTask and putIfAbsent() method from ConcurrentMap. - http://www.javaspecialists.co.za/archive/newsletter.do?issue=125 Other then lterate through the elements, adding and removing elements can also be problem, this article document a few good cases about that - http://rayfd.wordpress.com[..]en-a-synchronized-class-isnt-threadsafe/ Samples of using Queue.drainTo() - http://binkley.blogspot.com[..]rforming-fixed-amounts-of-work-with.html http://tech.puredanger.com/2009/02/28/java-7-transferqueue/ Overview of blockingqueue - http://tutorials.jenkov.com[..]/java-util-concurrent/blockingqueue.html Simple benchmark - http://java-persistence-performance.blogspot.com[..]jvm-performance-part-iii-concurrent.html Multi-thread behaviour - http://vanillajava.blogspot.com[..]hread-safety-issues-with-vector-and.html java.util.concurrent.ConcurrentHashMap VS openhft.collections.SharedHashMap - http://openhft.blogspot.co.uk[..]autilconcurrentconcurrenthashmap-vs.html Why are there so many concurrent queues implementations in Java? - https://vmlens.com/articles/cp/why_so_many_queues/ Why hashmap is not thread safe - https://www.pixelstech.net[..]a-HashMap-is-considered-as-thread-unsafe
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Sat Mar 28 20:09:46 HKT 2020
From /weblog/design/distribute
There are two key primary ways of scaling web applications which is in practice today. 1) “Vertical Scalability” - Adding resource within the same logical unit to increase capacity. An example of this would be to add CPUs to an existing server, or expanding storage by adding hard drive on an existing RAID/SAN storage. 2) “Horizontal Scalability” - Adding multiple logical units of resources and making them work as a single unit. Most clustering solutions, distributed file systems, load-balancers help you with horizontal scalability. Scalability can be further sub-classified based on the “scalability factor”. 1) If the scalability factor stays constant as you scale. This is called “linear scalability“. 2) But chances are that some components may not scale as well as others. A scalability factor below 1.0 is called “sub-linear scalability“. 3) Though rare, its possible to get better performance (scalability factor) just by adding more components (i/o across multiple disk spindles in a RAID gets better with more spindles). This is called “supra-linear scalability“. 4) If the application is not designed for scalability, its possible that things can actually get worse as it scales. This is called “negative scalability“. http://www.royans.net/arch/2007/09/22/what-is-scalability/ Report of building web application with 55k pageload with rail - http://shanti.railsblog.com[..]mongrels-handled-a-550k-pageview-digging XMPP a IM protocol about scalability - http://www.process-one.net[..]icle/the_aol_xmpp_scalability_challenge/ Presentation and resources of making you website more scalable - http://www.scribd.com[..]9/Real-World-Web-Performance-Scalability http://www.theserverside.com[..]lications&asrc=EM_NLN_3990118&uid=703565 http://www.theserverside.com[..]ionsPart2&asrc=EM_NLN_3990119&uid=703565 Brian Zimmer, architect at travel startup Yapta, highlights some worst practices jeopardizing the growth and scalability of a system: * The Golden Hammer. Forcing a particular technology to work in ways it was not intended is sometimes counter-productive. Using a database to store key-value pairs is one example. Another example is using threads to program for concurrency. * Resource Abuse. Manage the availability of shared resources because when they fail, by definition, their failure is experienced pervasively rather than in isolation. For example, connection management to the database through a thread pool. * Big Ball of Mud. Failure to manage dependencies inhibits agility and scalability. * Everything or Something. In both code and application dependency management, the worst practice is not understanding the relationships and formulating a model to facilitate their management. Failure to enforce diligent control is a contributing scalability inhibiter. * Forgetting to check the time. To properly scale a system it is imperative to manage the time alloted for requests to be handled. * Hero Pattern. One popular solution to the operation issue is a Hero who can and often will manage the bulk of the operational needs. For a large system of many components this approach does not scale, yet it is one of the most frequently-deployed solutions. * Not automating. A system too dependent on human intervention, frequently the result of having a Hero, is dangerously exposed to issues of reproducibility and hit-by-a-bus syndrome. * Monitoring. Monitoring, like testing, is often one of the first items sacrificed when time is tight. http://highscalability.com/scalability-worst-practices Useful Corporate Blogs that Talk About Scalability - http://highscalability.com[..]l-corporate-blogs-talk-about-scalability Overview of mapreduce and how it compare with other distributed programming model -http://natishalom.typepad.com[..]0/is-mapreduce-going-to-main-stream.html Paper of data store at amazon http://www.allthingsdistributed.com/2007/10/amazons_dynamo.html Discuss how haven't sync can cause performance issue - http://www.theserverside.com[..]lications&asrc=EM_NLN_6273194&uid=703565 http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6423457 Discussion about Cloud Based Memory Architectures - http://highscalability.com[..]ased-memory-architectures-next-big-thing http://highscalability.com[..]alability-and-performance-best-practices Interview with google engineer - http://www.zdnet.co.uk[..]gle-at-scale-everything-breaks-40093061/ Surprisingly youtube is blocking - http://highscalability.com[..]e-scalability-lessons-in-30-minutes.html If we are seeing a sustained arrival rate of requests, greater than our system is capable of processing, then something has to give. Having the entire system degrade is not the ideal service we want to give our customers. A better approach would be to process transactions at our systems maximum possible throughput rate, while maintaining a good response time, and rejecting requests above this arrival rate. - http://mechanical-sympathy.blogspot.com.au[..]apply-back-pressure-when-overloaded.html How twitter scaling - http://www.infoq.com/presentations/Twitter-Analytics How Reddit scaling - http://www.infoq.com/presentations/scaling-reddit How Hotjar scaling - https://www.hotjar.com[..]-while-scaling-hotjars-tech-architecture How infiniteDB prevent locking and IO - http://highscalability.com[..]-scalable-relational-database-manag.html http://highscalability.com[..]ard-way-about-scaling-a-million-use.html http://martin.kleppmann.com[..]2014/03/26/six-things-about-scaling.html The experiences of various big companies, about network issues - http://aphyr.com/posts/288-the-network-is-reliable Stackoverflow, scale without cloud - http://highscalability.com[..]nth-25-servers-and-i.html?SSLoginOk=true How netflix scale - http://highscalability.com[..]ix-what-happens-when-you-press-play.html Scaling to 100k Users - https://alexpareto.com[..]ity/systems/2020/02/03/scaling-100k.html https://www.infoq.cn/article/Tyx5HwaD9OKNX4xzFaFo
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Sun Mar 22 15:25:35 HKT 2020
From /weblog/business
Using game as training - http://cn.wsj.com/big5/20120514/eoe080717.asp?source=rss , and drawing for communication - http://cn.wsj.com/big5/20120514/eoe082405.asp?source=rss No control, but empower - http://www.michelemmartin.com[..]01/some-thoughts-on-managing-people.html 10 rules of success, not really very insighful ideas but still nice to take a look: http://draginol.joeuser.com/articles.asp?c=1&AID=114319 Another 10 tips for product manager - http://www.brainmates.com.au/?p=109 An interesting example of how people gaming the reward system - http://www.joelonsoftware.com/items/2007/05/10.html Interview of Jeff Bezos and learn about his management style - http://www.fastcompany.com/magazine/85/bezos_4.html Dos and Don'ts for line manager - http://blog.jezhumble.net/?p=29 8 elements of dysfunctional management - http://jchyip.blogspot.com[..]lements-of-dysfunctional-management.html Talk verse Action: All Talk and No Action - http://www.thekua.com[..]ectives-go-wrong-all-talk-and-no-action/ All Action and No Talk - http://www.thekua.com[..]ectives-go-wrong-all-action-and-no-talk/ A suggestion of taking the balance - http://www.scrumalliance.org/articles/61 Discussion about issues of managing remote teams - http://inhumanresources.blogspot.com/2008/01/1.html Team building with the way of "pointy haired boss" ?? - http://manincentral.blogspot.com/2008/02/blog-post_12.html Promote the problem maker to make them better?? Is that work? - http://manincentral.blogspot.com/2008/02/blog-post_16.html May be it is true that problem maker are innovator, give them more work and reward can change their negative performance to more than expected positive performance. The most consistent and intense complaint from team members was that their team leaders were unwilling to confront and resolve problems associated with poor performance by individual team members. http://www.codinghorror.com/blog/archives/001154.html Manage to learn - http://www.ft.com[..]dd-80e9-0000779fd18c.html?nclick_check=1 Suggestion about how to delegate to other, spend time to explain to vision - http://www.kui.name[..]E6%88%96%E8%80%85%E5%B4%A9%E6%BD%B0.html Allocate free time to employee is good for company - http://www.codinghorror.com[..]12/08/today-is-goof-off-at-work-day.html What management should be - http://www.jrothman.com[..]-people-can-you-manage-as-a-manager.html 1. 清楚意識到您的創新意圖 2. 為彈性的工作時間設計一個架構 ３、涉入，然後再把手收回去 4. 測量什麼是有意義的 5. 給予「無實質價值」的報酬 6. 象徵化 7. 不是標準化地複製他人的創新行為 http://www.inside.com.tw/2014/01/15/6-way-innovation-culture http://www.fastcodesign.com[..]6-ways-to-create-a-culture-of-innovation 1. 在公司裡跟別人吐露的心事越少，對你越好。你以為是無傷大雅的閑聊，其實有可能會造成嚴重傷害。把你的猜測和擔憂都埋在心裡吧。 2. 務必管理好和下屬的關系。花時間和公司裡的較低層員工在一起，盡量對他們友好。對電梯操作員禮貌問候，對郵遞員表示感謝，對助理說句友善的話，這些都會得到讚賞。打造名譽要從基層做起。同樣的，碰到不爽的事情，要自己消化情緒，不要在別人面前發泄。 3. 做領導是一份全職工作，職責的時鐘永不停止。每個微小的跡象都會被解讀，你的不耐煩、失望或不安全感都會被那些解讀你的人放大。不應做出隨意、毫無準備的坦白，信息必須經過深思熟慮才能發出。要特別小心書面的東西，尤其是電子郵件──它們永遠都不會消失。 4. 保持聆聽並索取建議。每周至少在公司餐廳吃一次午飯，或者時不時在咖啡機旁逗留，聽聽其他人都在聊些什麼。如果有人想跟你說話，那就沒有理由不聽。如果有人批評，即使你不讚同也要花時間仔細回應。 5. 你覺得很風趣的俏皮話通常並不風趣。你的幽默感很容易被解讀為自傲和笨拙。如果你仍然以為講笑話或引用某個幽默故事對陳述觀點很重要，那麼請先跟你的配偶或信任的朋友演練一遍。幽默是有風險的。千萬不要拿嚴肅的事情開玩笑。 6. 很重要的一點是，保証重要事務的重要性。應該經常解釋你的戰略，可以換個措辭，但要反復強調。 7. 絕不要抱怨和解釋，沒有人會聽。出了差錯就承擔責任。不要把錯誤怪到前幾屆管理層、天氣、運氣不好或競爭對手身上。但也不要露出防御姿態。向前看──除非上級要求你辭職。 8. 信任你的專業顧問，接受他們的專業意見。不要對市場做過多猜測。沒有所謂的完美數據。做出決策，往前走。 9. 謹慎使用“平均”這個詞──平均深度為6英寸河也可能淹死人。欣然接受“平均”，只會獲得虛假的安全感。假設最糟糕的情況會發生，因為通常就是如此。 10. 最後這條是陳詞濫調，但卻是至理真言：絕不要做或說你不希望在報紙頭條看到的事情。和媒體打交道時，不要回答假設性的問題，謹記麥克風永遠不會真正關閉，絕不要同意“私下”談。對一場危機唯一值得做的公開回應是誠實。 http://cn.wsj.com/big5/20140318/eoe074616.asp?source=rss http://online.wsj.com[..]0001424052702303519404579353060931625306 給新手高管的10條建議 - http://cn.wsj.com/big5/20140318/eoe074616.asp?source=rss http://jchyip.blogspot.com[..]/causes-and-solutions-for-bystander.html 以競爭激發員工潛力有其道理，但就我過往所見，鼓催互鬥文化往往淪為非實力較量，最後變成內部互搞小動作放毒箭，對公司產生最嚴重的破壞 － 內耗。 - http://thehousenewsbloggers.net[..]%84%EF%BC%9F%EF%BC%8F%E5%BE%90%E7%B7%A3/ Good developer cannot be good manager? - http://discuss.joelonsoftware.com/default.asp?joel.3.172310 Manager guide in google - https://www.infoq.com/news/2017/02/google-managers Every person is a vector — add them all up, and you know how much progress your company is going to make. - https://thinkgrowth.org[..]me-about-growing-a-business-c2c173f5bff3 The Seven Habits of One Highly Effective Manager of Managers: Things I Learned from Charity Majors - https://honkathon.com/2019-12-19-seven-habits https://codahale.com/work-is-work/
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Mon Mar 16 07:46:47 HKT 2020
From /weblog/web/script
How I made a 3D game in only 2KB of JavaScript - http://frankforce.com/?p=7427
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