Programmer Group

Error stack as fllow: 2017-07-10T08:41:36,134 ERROR [task-runner-0-priority-0] io.druid.indexing.overlord.ThreadPoolTaskRunner - Exception while running task[HadoopIndexTask{id=index_hadoop_pageviews_2017-07-10T08:40:32.650Z, type=index_hadoop, dataSource=pageviews}] java.lang.RuntimeException: java.lang.reflect.InvocationTargetException a ...

Introduction of ZuulZuul is a load balancer based on JVM routing and server, which provides dynamic routing, monitoring, resilience, security and other edge services on cloud platform. Source of articles Javaa B2B2C Imitating Taobao Electronic Mall SystemRouting function: equivalent to the reverse proxy function of nginx.For example: / You may ...

Preface Object wait/notify method is a thread synchronization method based on Object Monitor provided by early JVM. This paper first introduces the related data structures (classes), then starts with the internal implementation of wait/notify method, and briefly analyses the principle and implementation of Object Monitor. Park PlatformParker Ob ...

JNI accesses Java instance variables and static variables Instance variables and static variables in Java, how to access and modify them in local code. Static variables, also known as class variables (attributes), share the same data in all instance objects and can be accessed directly by class name and variable name. Instance variables are als ...

The first is to create a class that inherits the Thread class and override the run method of the Thread class. The code is as follows: class Thread1 extends Thread { @Override public void run() { while (true) { try { Thread.sleep(1000);// Thread Sleep 1 s } catch (InterruptedException e) ...

First, the producer-consumer model The producer-consumer model is a common one. When both producers and consumers have only one model, it is also called the Pipe model, i.e. the pipeline model. In the producer-consumer mode, data is transmitted to each other through Channel, which is the channel. Then, in what order the data is transmitted in ...

1. Edit profile file export JAVA_HOME=/usr/lib/jvm/jdk/ export HADOOP_INSTALL=/sur/local/hadoop export PATH=$PATH:$HADOOP_INSTALL/bin export PATH=$PATH:$HADOOP_INSTALL/sbin export HADOOP_MAPRED_HOME=$HADOOP_INSTALL export HADOOP_COMMON_HOMR=$HADOOP_INSTALL export HADOOP_HDFS_HOME=$HADOOP_INSTALL export YARN_HOME-$HADOOP_INSTAL ...

Java provides eight basic data types, each of which has its corresponding packaging type. The packaging class is an object-oriented class and a high-level data type. It can carry out some more complex operations. They are reference type instead of basic type. Corresponding relationship between basic type and packaging type Basic types ...

Once synchronized modification is added to the method of the object, only one thread can access the synchronized modification method at any time. Assuming that a data object has write and read methods, in order to ensure the security of data in multithreaded environment, synchronized synchronized block is added to the read and write methods of ...

Excerpt from Professor Zhou Zhiming's "Deep Understanding of Java Virtual Machine: Advanced Features and Best Practices of JVM" 13.2.2 Thread Safety Implementation Method 1. Noun Interpretation Synchronization is to ensure that shared data is accessed by only one thread at the same time when the lock thread accesses shared data concur ...