Hs java open_party

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话题来自OpenParty “清雨榕香”活动

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  • What if all previous best prestise cannot meet your need? You would like to optimize your application manually?
  • msdk – This tool can be used to do detailed performance analysis of concurrent Java applications. It does an in-depth analysis of the complete execution stack, starting from the hardware to the application layer. Information is gathered from all four layers of the stack – hardware, operating system, jvm and application.
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  • For multi-thread application, lock-free approach is different with lock-based approach in several aspects: When accessing shared resource, lock-based approach will only allow one thread to enter critical section and others will wait for it On the contrary, lock-free approach will all every thread to modify state of shared state. But one of the all threads can succeed, and all other threads will be aware of their action are failed so they will retry or choose other actions.
  • The real difference occurs when something bad happens to the running thread. If a running thread is paused by OS scheduler, different thing will happen to the two approach: Lock-based approach: All other threads are waiting for this thread, and no one can make progress Lock-free approach: Other threads will be free to do any operations. And the paused thread might fail its current operation From this difference, we can found in multi-core environment, lock-free will have more advantage. It will have better scalability since threads don’t wait for each other. And it will waste some CPU cycles if contention. But this won’t be a problem for most cases since we have more than enough CPU resource 
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