willpower
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bailangfei3344：
自我介绍 -
regionwar：
你好，转化为人为：1、不该加锁的不要加锁:局部变量，单线程占用 ...
关于java锁机制的优化 -
danni505：
希望能交流：
msn:danni-505#hotmail.co ...
关于java锁机制的优化 -
ouspec：
收藏的东西不错。
TOP500 -
willpower：
The idea behind is e-sync IO do ...
Rethink the sync
文章列表
JVM 级别的锁机制的优化主要针对这两种情况:
1> 大多数情况不会存在竞争的锁.
2> 被频繁竞争的锁.
以下采用事例的方式加以说明. 前三种方法是针对情况1>, 最后一种是针对情况2>.
1. lock elision
public String getStoogeNames() ...
- 2008-10-21 17:14
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你说这一帮哲学家聚到一起吃饭，还一人只有一根筷子，还要吃口饭，放下筷子思考一下。
当他们都拿起一根筷子时，发现还少根筷子，谁也不肯放下手中的筷子。结果是都只能饿死了。
哎。。。这样不行啊。
BTW, 这样吃饭好像很不卫生吧.
- 2008-10-21 13:45
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Here is a simple benchmark case for testing the performance between ReentrantLock and Synchronized.
Machine: 2 phycial processors with hyperthreading enabled (4 logical processors)
OS: windows server 2003
JVM version: 1.6
Threads Number: 4
Benchmark result:
Synchronized - 25786ms
ReentrantLock ...
- 2008-10-20 17:57
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Everytime, when people mention about performance test, some guys would stand out and say: aha, performance test, using loadrunner, collecting performance data, that's it. So, there are many docs talking about how to use loadrunner, and even more documents on loadrunner questions for performance testi ...
- 2008-10-16 15:25
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我们知道最简单的情况下有如下公式：
Throughput = 1 / responseTime (1)
现实情况是用户在提交一个请求后并不会立即发第二个请求，比如用户打开一个页面后，他可能会花些时间来浏览它，我们把这个时间叫思考时间：ThinkTime, 那么公式(1)则进化为：
Throughput = 1 / (thinkTime + responseTime) (2)
以上公式是在单用户的情况下， 多用户下还要引入活动用户(active user)的概念,公式(2)进化为：
Throughput = activeUserNumber / (th ...
- 2008-10-08 14:33
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严格上讲，scalability还没有正式定义， 甚至有人觉得这样的词完全是带有商业味的。但我觉得以下的解释很直观：
(from Steve Haines)
performance
measures the
speed with which a single request can be executed, while scalability
measures the ability of a request to maintain its performance under
increasing load. For example, the performance of a requ ...
- 2008-10-07 14:07
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All performance articles are only based on my experience. The purpose that I put them here is trying to collect and shape my thoughts.
You may find something lose or wrong. Please leave me some notes. Then, I will be able to fix them.
Thanks.
- 2008-07-01 11:32
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Kirk Pepperdine's attendence of AMD's performance talk at JavaOne produced a cascade of fascinating memories about Cray optimizations. Here, Kirk relates some of the most interesting optimizations that helped make Cray's superfast - and how that relates to your Java programs. Published July 2007, Aut ...
- 2007-08-29 15:54
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1. http://www.ibm.com/developerworks/java/
library/j-jtp11234/
---------------------------------------
2.
wait free synchronization
- 2007-06-18 22:06
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解决方案就是:在启动服务器时加上指定PermGen区域的内存大小的配置.-XX:PermSize=128m -XX:MaxPermSize=256m
比如:nohup /usr/java/jdk1.5.0_08/bin/java -Dcom.sun.management.jmxremote -Xms512m -Xm
x1024m -XX:=128m -XX:MaxPermSize=256m -jar oc4j.jar&
HOHO,问题解决了,上网查了一个PermGen space是咋回事,原来:
PermGen space的全称是Permanent Genera ...
- 2007-06-05 18:07
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« I used to work for... | Main | Usability for Programmers »
Google TechTalk: Open Source Performance Testing
Goranka Bjedov - Using Open Source Tools for Performance Testing, Google TechTalk, 8 September 2006.
Goranka provides a great overview of how Google are doing performance testing
" ...
- 2007-06-05 15:11
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http://www.isaacmao.com/meta/2006/07/how-to-view-google-video-locally-in.html
- 2007-06-05 15:10
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数据仓库，英文名称为Data Warehouse，可简写为DW。
数据仓库之父Bill Inmon在1991年出版的“Building the Data Warehouse”一书中所提出的定义被广泛接受——数据仓库（Data Warehouse）是一个面向主题的（Subject Oriented）、集成的（Integrated）、相对稳定的（Non-Volatile）、反映历史变化（Time Variant）的数据集合，用于支持管理决策(Decision Makin ...
- 2007-04-18 10:38
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全球500强
http://cn.biz.yahoo.com/overseas/top500.html
- 2007-04-16 17:43
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Expressions, Conversion and Evaluation with C
(All you need to know about Expressions)
In this tutorial, I will be writing in detail about an important programming concept i.e. Algebraic Expressions, different expression notations like Prefix, Postfix and Infix evaluation of the expressions, how to ...
- 2007-04-13 11:13
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