laskfla

import java.io.File;
import java.util.*;
import java.lang.management.BufferPoolMXBean;
import java.lang.management.ManagementFactory;
import javax.management.MBeanServerConnection;
import javax.management.ObjectName;
import javax.management.remote.*;

import com.sun.tools.attach.VirtualMachine; // Attach API

laskfla

########Queries with For#######
//the insight from Sir.M
For expression is very similar to the common operations of query language for database.
For has "if" for filter and nested form "for" expression is similar to the join in database.
(The collection returned could be then reduced/aggregated ,deduped/distinct , etc)

For example: Suppose that we have a database books, represented as a list of books .
    case class Book(title : String, authors : List[String])
 
 //the argument could be passed in  "parameter name = value" form  

laskfla

import java.io.*;
import java.util.*;
import sun.jvm.hotspot.memory.*;
import sun.jvm.hotspot.oops.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.tools.*;
import sun.jvm.hotspot.utilities.*;

public class DirectMemorySize extends Tool {

laskfla

Latency Comparison Numbers
--------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

laskfla

List of threads:

4210 Thread-4
4208 WatcherThread
4209 Timer-0
4207 Low Memory Detector
4206 C2 CompilerThread1
4205 C2 CompilerThread0
4204 Signal Dispatcher
4203 Finalizer