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I'm a Software Engineer working at WSO2. Please check my company profile at http://wso2.com/about/team/isuru-perera/

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Benchmarking Java Locks with Counters

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These days I am analyzing some Java Flight Recordings from taken from WSO2 API Manager performance tests and I found out that main processing threads were in "BLOCKED" state in some situations. The threads were mainly blocked due to "synchronized" methods in Java. Synchronizing the methods in a critical section of request processing causes bottlenecks and it has an impact on the throughput and overall latency. Then I was thinking whether we could avoid synchronizing the whole method. The main problem with synchronized is that only one thread can run that critical section. When it comes to consumer/producer scenarios, we may need to give read access to data in some threads and write access to a thread to edit data exclusively. Java provides ReadWriteLock for these kinds of scenarios. Java 8 provides another kind of lock named StampedLock . The StampedLock provides an alternative way to the standard  ReadWriteLock  and it also supports optimistic...
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Java CPU Flame Graphs

Update (September 14, 2015): Java 8 Update 60 was released on August 18, 2015. There are some recent changes to "perf-map-agent". There is no longer a script named "perf-java" and you should use "bin/create-java-perf-map.sh " Brendan Gregg shared an exciting news in his Monitorama talk: The " JDK-8068945 " is fixed in Java 8 Update 60 Build 19 ! Without this fix, it was not possible to see full stack in Java with Linux perf_events and standard JDK (without any patches). For more information, see Brendan's Java CPU Flame Graphs page. The Problem with Java and Perf First of all, let's see what's the problem with using current latest Java and perf. For this example, I used the same program explained in my previous blog post regarding FlameGraphs . java org.wso2.example.JavaThreadCPUUsage.App Then I sampled on-CPU functions for Java program using perf. (See Brendan's Perf Examples ) sudo perf record -F 99 -g -...
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Vacation!

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I have been waiting for almost 2 years to create a blog.. and finally my dream came true.. Yes! it's vacation! I had so many plans after I completed the exam in June. I was bit scared about the exam as I couldn't try my best at the exam. I got my results this month and I'm happy about my marks. One of my plans was to create my own blog.. I'm very much inspired by some of my friends' blogs and I wanted my own blog badly. Actually, I'm writing this post after 19 days creating this blog. I didn't get much "free time" as expected. These days I'm very busy with my office work. Sometimes, I fed up with programming, as I'm staring at the monitor 10 hours per day! But I enjoy what I'm doing. These days we're developing a web application using ICEfaces , Spring and Websphere eXtreme Scale . Working with new technology is always very interesting. But I'm exhausted..... Best thing happened in this vacation was our batch trip. We all went ...
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