The History of Computer Chess: An AI Perspective

Very impressive talk with chess authorities and computer scientists.

David Levy, Knuth (talking about its paper alpha-beta).

Decompiling Java

Simple example:

public class Hola {

    public static void main(String[] args) {

        double pi = 3.14156;
       
        System.out.println("pi="+pi);
       
    }
}

Using javap -c can be solved:

$ javap -c Hola.class Compiled from "Hola.java"
public class Hola {
  public Hola();
    Code:
       0: aload_0      
       1: invokespecial #8                  // Method java/lang/Object."":()V
       4: return       

  public static void main(java.lang.String[]);
    Code:
       0: ldc2_w        #16                 // double 3.14156d
       3: dstore_1     
       4: getstatic     #18                 // Field java/lang/System.out:Ljava/io/PrintStream;
       7: new           #24                 // class java/lang/StringBuilder
      10: dup          
      11: ldc           #26                 // String pi=
      13: invokespecial #28                 // Method java/lang/StringBuilder."":(Ljava/lang/String;)V
      16: dload_1      
      17: invokevirtual #31                 // Method java/lang/StringBuilder.append:(D)Ljava/lang/StringBuilder;
      20: invokevirtual #35                 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
      23: invokevirtual #39                 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
      26: return       
}

javap -verbose MyClass | grep "major"

to know java version.

Haskell Cheat Sheets

http://cheatsheet.codeslower.com/

https://matela.com.br/pub/cheat-sheets/
https://matela.com.br/pub/cheat-sheets/haskell-cs-1.1.pdf

http://www.cheat-sheets.org/saved-copy/Haskell.Haskell_Cheat_Sheet.pdf

https://cheat.readthedocs.io/en/latest/haskell.html

https://gist.github.com/caiorss/a39a48c4966355188f95cb9b0cf94b20

common log4j2/slf4 error by duplication

####<Nov 23, 2018 12:20:05 PM CLST> <Error> <Deployer> <machine1> <WLSSandbox01> <[STANDBY] ExecuteThread: '3' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1542986405456> <BEA-149231> <Unable to set the activation state to true for the application "foo-bar-qux-rest".
weblogic.application.ModuleException: java.lang.NoClassDefFoundError: org/apache/logging/log4j/util/ReflectionUtil
    at weblogic.application.internal.ExtensibleModuleWrapper.start(ExtensibleModuleWrapper.java:140)
    at weblogic.application.internal.flow.ModuleListenerInvoker.start(ModuleListenerInvoker.java:124)
    at weblogic.application.internal.flow.ModuleStateDriver$3.next(ModuleStateDriver.java:216)
    at weblogic.application.internal.flow.ModuleStateDriver$3.next(ModuleStateDriver.java:211)
    at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:42)
    at weblogic.application.internal.flow.ModuleStateDriver.start(ModuleStateDriver.java:73)
    at weblogic.application.internal.flow.StartModulesFlow.activate(StartModulesFlow.java:24)



---


<Feb 22, 2019 1:14:48,804 PM CLST> <Error> <Console> <BEA-240003> <Administration Console encountered the following error: weblogic.application.ModuleException: java.lang.IncompatibleClassChangeError: Class org.apache.logging.slf4j.Log4jLoggerFactory does not implement the requested interface org.slf4j.ILoggerFactory
    at weblogic.application.internal.ExtensibleModuleWrapper.start(ExtensibleModuleWrapper.java:140)
    at weblogic.application.internal.flow.ModuleListenerInvoker.start(ModuleListenerInvoker.java:124)
    at weblogic.application.internal.flow.ModuleStateDriver$3.next(ModuleStateDriver.java:216)
    at weblogic.application.internal.flow.ModuleStateDriver$3.next(ModuleStateDriver.java:211)
    at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:42)

Haskell Ubuntu install

sudo apt-get install -y software-properties-common
sudo add-apt-repository ppa:hvr/ghc
sudo apt-get update
sudo apt-get install ghc-8.6.3
sudo apt-get install cabal-install-2.4


i.e.:
export PATH=/opt/ghc/8.0.2/bin/:$PATH
export PATH=/opt/ghc/bin/:$PATH

multiple ghc:
$ activate-hs
You must be root to activate a particular Haskell Platform.
Please rerun this command sudo:
    sudo /usr/local/bin/activate-hs 

Architecture and Design trends 2019 Q1

http://infoq.link/architecture-trends-2019

Log4j2 name JMX MBeans

To let name through JMX at MBeans, this can be assigned through

        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-web</artifactId>
            <version>${log4j2.version}</version>
            <scope>provided</scope>
        </dependency>
      
and can be customized:

    <context-param>
        <param-name>log4jContextName</param-name>
        <param-value>spring-mvc-simple-32-nombre</param-value>
    </context-param>


https://logging.apache.org/log4j/2.x/manual/webapp.html

It must be web.xml 3.0

WebLogic log4j2 asm

At starting or deploying time the next exception can be thrown with WebLogic Server :

Caused By: java.lang.IllegalArgumentException
        at com.bea.objectweb.asm.ClassReader.(Unknown Source)
        at com.bea.objectweb.asm.ClassReader.(Unknown Source)
        at weblogic.application.utils.annotation.ClassInfoImpl.(ClassInfoImpl.java:41)
        at weblogic.application.utils.annotation.ClassfinderClassInfos.polulateOneClassInfo(ClassfinderClassInfos.java:240)
        at weblogic.application.utils.annotation.ClassfinderClassInfos.populateClassInfos(ClassfinderClassInfos.java:193)
        at weblogic.application.utils.annotation.ClassfinderClassInfos.(ClassfinderClassInfos.java:44)
        at weblogic.servlet.internal.War.initializeClassInfosIfNecessary(War.java:446)
        at weblogic.servlet.internal.War.getAnnotatedClasses(War.java:376)
        at weblogic.servlet.utils.WarUtils.isJsfApplication(WarUtils.java:258)
        at weblogic.servlet.internal.WebAppModule.detectJsfApplication(WebAppModule.java:277)
        at weblogic.servlet.internal.WebAppModule.init(WebAppModule.java:262)
        at weblogic.servlet.internal.WebAppModule.init(WebAppModule.java:682)
        at weblogic.application.internal.flow.ScopedModuleDriver.init(ScopedModuleDriver.java:162)
        at weblogic.application.internal.ExtensibleModuleWrapper.init(ExtensibleModuleWrapper.java:98)
        at weblogic.application.internal.flow.ModuleListenerInvoker.init(ModuleListenerInvoker.java:84)
        at weblogic.application.internal.flow.InitModulesFlow.initModule(InitModulesFlow.java:288)
        at weblogic.application.internal.flow.InitModulesFlow.initModules(InitModulesFlow.java:301)
        at weblogic.application.internal.flow.InitModulesFlow.prepare(InitModulesFlow.java:329)
        at weblogic.application.internal.BaseDeployment$1.next(BaseDeployment.java:706)
        at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:42)
        at weblogic.application.internal.BaseDeployment.prepare(BaseDeployment.java:237)
        at weblogic.application.internal.EarDeployment.prepare(EarDeployment.java:61)
        at weblogic.application.internal.DeploymentStateChecker.prepare(DeploymentStateChecker.java:158)
        at weblogic.deploy.internal.targetserver.AppContainerInvoker.prepare(AppContainerInvoker.java:61)
        at weblogic.deploy.internal.targetserver.operations.ActivateOperation.createAndPrepareContainer(ActivateOperation.java:208)
        at weblogic.deploy.internal.targetserver.operations.ActivateOperation.doPrepare(ActivateOperation.java:98)
        at weblogic.deploy.internal.targetserver.operations.AbstractOperation.prepare(AbstractOperation.java:233)
        at weblogic.deploy.internal.targetserver.DeploymentManager.handleDeploymentPrepare(DeploymentManager.java:749)
        at weblogic.deploy.internal.targetserver.DeploymentManager.prepareDeploymentList(DeploymentManager.java:1238)
        at weblogic.deploy.internal.targetserver.DeploymentManager.handlePrepare(DeploymentManager.java:252)
        at weblogic.deploy.internal.targetserver.DeploymentServiceDispatcher.prepare(DeploymentServiceDispatcher.java:172)


This is caused by having .class bytecode bigger than accepted

Tag: ASM_5_0

        // checks the class version
        if (readShort(off + 6) > Opcodes.V1_8) {
            throw new IllegalArgumentException();
        }
  
One workaround is to remove the classes compiled with the newest bytecode (> 1.8 > 52)

more details:

https://issues.apache.org/jira/browse/LOG4J2-2124

http://mail-archives.apache.org/mod_mbox/logging-notifications/201711.mbox/%3CJIRA.13120226.1511356169000.299143.1511356200159@Atlassian.JIRA%3E

https://gitlab.ow2.org/asm

Busy Socket

Common issue when reading from a socket without timeout:

"main" prio=10 tid=0x00007f79a4009800 nid=0x32ec runnable [0x00007f79aa67a000]
   java.lang.Thread.State: RUNNABLE
    at java.net.SocketInputStream.socketRead0(Native Method)
    at java.net.SocketInputStream.read(SocketInputStream.java:153)
    at java.net.SocketInputStream.read(SocketInputStream.java:122)
    at java.io.ObjectInputStream$PeekInputStream.read(ObjectInputStream.java:2664)
    at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2680)
    at java.io.ObjectInputStream$BlockDataInputStream.readShort(ObjectInputStream.java:3157)
    at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:865)
    at java.io.ObjectInputStream.(ObjectInputStream.java:362)
    at com.sun.btrace.client.Client.submit(Client.java:402)
    at com.sun.btrace.client.Main.main(Main.java:206)

---

      sock.setSoTimeout(5 * 1000); //milliseconds

Other details on sockets:

• https://devwebcl.blogspot.com/2018/12/most-interesting-socket-options.html
• https://docs.oracle.com/javase/7/docs/api/java/net/Socket.html#connect(java.net.SocketAddress,%20int)

Btrace cheat sheet

Btrace is a not very popular and powerful tool to debug class at runtime.

The plugin must be installed to run it from visualvm:

Second button to execute it:

Copy the script to be executed thru btrace :

See the results:

It can be executed through command line as well:

btrace <pid> <btrace-script>

$ ./btrace -v -p 2020 -d ./dump/ 64834 TracingScript.java 


More info:

1. https://github.com/btraceio/btrace
2. https://dzone.com/articles/btrace-hidden-gem-java
3. https://www.zcfy.cc/original/btrace-wiki-userguide-mdash-project-kenai