Mobility

Storm UI OverviewStorm UI is very helpful for troubleshooting issues encountered during Storm usage, but some properties have unclear meanings. Although they are all simple concepts, not knowing them can be quite frustrating. One thing to note: when you hover over the title bar in the UI, you can see the specific details of that property. Several highly-ranked Google articles are essentially just organizing this information. Most properties are straightforward — you know what they mean just b...

Problem SymptomsRecently, while using ActiveMQ’s connection pool, I discovered a very serious memory leak issue. Investigation ProcessThrough jmap monitoring, it can be seen that java.util.concurrent.locks.ReentrantLock and org.apache.activemq.pool.PooledConnection occupy a very large amount of memory, and the growth rate is also very fast. Root Cause AnalysisAfter searching online, I found exactly the corresponding ActiveMQ bug report: https://issues.apache.org/jira/browse/AMQ-3997 SolutionT...

Test ScenarioThe company uses ActiveMQ and Camel for message distribution. Previously, the data volume wasn’t very large, so we never really considered efficiency issues, and the research into Camel’s working principles wasn’t deep. However, recently, as the business volume increased, Camel’s efficiency has gradually become a bottleneck, so I got a general understanding of Camel’s working principles based on logs. Although Camel is embedded into ActiveMQ, during the working process, Camel and...

Reposted from http://leyew.blog.51cto.com/5043877/860255#559183-tsina-1-46862-ed0973a0c870156ed15f06a6573c8bf0 A few days ago I started learning LDA, took many detours, and was still completely confused about LDA. After reading this document, I finally understood what LDA is for.   LDA (Latent Dirichlet Allocation) Learning NotesI’ve been studying the LDA algorithm recently, and after a few days of struggle, I’ve finally gained a rough understanding of the overall framework and process o...

OverviewReference: http://www.cnblogs.com/xia520pi/archive/2012/05/16/2504205.html   12345678910111213141516171819202122232425262728package org.apache.hadoop.examples;import java.io.IOException;import java.util.StringTokenizer;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.IntWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Job;import org.apache.hadoop.mapreduce.Mapper;import org.apache.hadoop.mapreduce...

⚠️ These are study notes from 2012. The Hadoop ecosystem has changed dramatically over the past decade. The links below are very outdated. I’ve preserved the original content as a historical record and added 2026-era learning recommendations. Why Learn About Hadoop in 2026?You might wonder: with Spark, Flink, and data lakes everywhere, why bother with Hadoop? The answer is simple: HDFS and YARN remain the foundation of big data infrastructure. Spark runs on YARN by default, Hive table dat...