jvm

问题 I'm trying to use the ASM library to translate byte code into a different format, which can be done with a MethodVisitor, as with this simple test code: return new MethodVisitor(ASM7) { @Override public void visitInsn(int opcode) { System.out.println(String.format("%02x", opcode)); } @Override public void visitMaxs(int maxStack, int maxLocals) { System.out.println(maxStack); } }; One issue is that I only get to see maxStack after the actual instructions – I've tested it, and that is the order

问题 I'm trying to use the ASM library to translate byte code into a different format, which can be done with a MethodVisitor, as with this simple test code: return new MethodVisitor(ASM7) { @Override public void visitInsn(int opcode) { System.out.println(String.format("%02x", opcode)); } @Override public void visitMaxs(int maxStack, int maxLocals) { System.out.println(maxStack); } }; One issue is that I only get to see maxStack after the actual instructions – I've tested it, and that is the order

问题 When I was reading Thinking in Java (4th Edition) recently, I got a problem about method binding in Java. First let's look at two definitions from the book: Connecting a method call to a method body is called binding. All method binding in Java uses late binding unless the method is static or final. you can find those definitions in section Method-call binding from chapter Polymorphism . (page 281-282) To testify that, I wrote the following code: public class Test3{ public static void main

问题 When I was reading Thinking in Java (4th Edition) recently, I got a problem about method binding in Java. First let's look at two definitions from the book: Connecting a method call to a method body is called binding. All method binding in Java uses late binding unless the method is static or final. you can find those definitions in section Method-call binding from chapter Polymorphism . (page 281-282) To testify that, I wrote the following code: public class Test3{ public static void main

问题 The Scala compiler generates byte code like Java compiler which could be run on a platform dependent JVM right?Then why do we need complete JDK as a pre-requisite?Is it for including few Java items within scala and debugging it?Please provide some insights. 回答1: I've just tested this claim on a system with sbt and a JRE but no JDK. Compiling works fine: the JDK is not required. You'll need it for jarsigner if you are going to sign your .jar files or do other obscure things. 回答2: From the

问题 The Scala compiler generates byte code like Java compiler which could be run on a platform dependent JVM right?Then why do we need complete JDK as a pre-requisite?Is it for including few Java items within scala and debugging it?Please provide some insights. 回答1: I've just tested this claim on a system with sbt and a JRE but no JDK. Compiling works fine: the JDK is not required. You'll need it for jarsigner if you are going to sign your .jar files or do other obscure things. 回答2: From the

问题 I am trying to increase heap size for wildfly in docker container. This is easily done by updating wildfly/bin/standalone.conf in a regular wildfly setup. Our base docker image for wildfly has a default heapsize of 512 MB which is required to be 1GB in one of the web apps. One way to go is by simple text replace in the Docker file using sed command - RUN sed -i -- 's/JAVA_OPTS="-Xms64m -Xmx512m -XX:MaxPermSize=256m/JAVA_OPTS="-Xms2048m -Xmx6144m -XX:MaxPermSize=256m/g' /path/standalone.conf I

问题 I am trying to increase heap size for wildfly in docker container. This is easily done by updating wildfly/bin/standalone.conf in a regular wildfly setup. Our base docker image for wildfly has a default heapsize of 512 MB which is required to be 1GB in one of the web apps. One way to go is by simple text replace in the Docker file using sed command - RUN sed -i -- 's/JAVA_OPTS="-Xms64m -Xmx512m -XX:MaxPermSize=256m/JAVA_OPTS="-Xms2048m -Xmx6144m -XX:MaxPermSize=256m/g' /path/standalone.conf I

问题 I have a tiny java console application which I would like to optimize in terms of memory usage. It is being run with Xmx set to only 64MB. The overall memory usage of the process according to different monitoring tools (htop, ps, pmap, Dynatrace) shows values above 250MB. I run it mostly on Ubuntu 18 (tested on other OS-es as well). I've used -XX:NativeMemoryTracking java param and Native Memory Tracking with jcmd to find out why so much more memory is used outside of the heap. The values

问题 I am bit confused with the terms of cross platform and cross compiler. Let me be first clear about the cross platform. When people talk about cross platform it means the architecture of the CPU, i.e, X86 and X64 ? or the OS i.e windows 32 bit or Windows 64 (server or desktop)? UNIX doesn't have different flavours like 64 bit or 32 bit. Why so? .NET and java is cross compiler language, what it means? When the program is compiled in .NET, we have to choose the option like X86, X64 or Any CPU.