老程序员的一点总结之性能

老程序员的一点总结之性能

标签（空格分隔）： 性能 调优

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不精。

分类

数据处理，数据I/O
代码级的优化要定位到进程线程函数级别

数据处理

1. CPU
   用 visualvm 找 “methods with high total time percentage and simultaneously big self-time” 和 ""odd" methods that spend more time than they should due to a bug or unmet assumption"

参考：http://clojure-goes-fast.com/blog/profiling-tool-jvisualvm/

数据I/O

1. MEMORY
   看visualvm指标，"how long a certain method has been suspened by Garbage collection","which types of objects are allocated most and where these allocations occur"

参考：https://www.dynatrace.com/resources/ebooks/javabook/analyzing-java-memory/

2. NETWORK
   iptraf(iptraf-ng)

3. DISK
   iotop

开源/框架系统配置会导致I/O问题，通过理解配置对应的实现深入理解配置，进行调整。