Focus of the training is to make JVM and Java performance tuning clear and simple as possible for the participants at the design, architecture and, implementation levels.

Cache and Memory

• Measure the effects of cache on a java program

• Identifying bottlenecks with the help of these measurements

• Measuring TLBs performance and its effects

• Keeping latency low and throughput high by engaging the cache

• Associating bottlenecks with java code.

• How Hardware effects Performance of JAVA application?

• Measure the effects of other processor and hardware Counters on a java program

• Hardware counters that can be measured

• Hardware and software Prefetchers

• TLBs effect on java code.

• TLBs architecture

• How cache effects performance?

• Crash Course in modern hardware

• Cache Levels and their architecture

Disk

• How to measure tardy disk?

• Identifying with correct reason

• Is your disk IO slow?

• Reasons for tardy performance.

• Associating the tardy performance with java code

Locking and Concurrency​​​​​​​

• Cache Coherency

• MESI

• False Sharing

• Associating False Sharing with Java Code

• Detecting False Sharing

Processor Affinity

• Effects of processor affinity

• Measuring effects of affinity

CPU​​​​​​​

• Measuring CPI and IPC

• CPU Performance Counters

• Associating and CPI and IPC with performance and java code

Virtual Memory

• Page Replacement

• Caveats of using TLB

• Introduction

• How physical memory acts

• Swap Space

• Pages and page frames

• Multilevel page tables

• How the operating system sees memory

• Optimizing Page table access

• How virtual memory acts

• Virtual memory and shared memory

• Demand Paged Virtual Memory and Working Sets

• Influencing TLB performance

JVMTuning for VirtualMemory​​​​​​​

• -XX:_UseLargePages

• /sys/kernel/mm/transparent_hugepages/enabled

• /proc/sys/vm/nr_hugepages

• /proc/meminfo Hugepagesize

• Linux huge Pages

• Linux Transparent huge pages

• LargePages

Locking and Concurrency​​​​​​​

• is_lock_owned

• try_spin

• Object layout with JOL

• spin_pause

• Undestanding Padding

• False Sharing

• Designing Classes to avoid false share

• @Contended and related annotation

• complete_monitor_locking

Setting Processor Affinity at OS​​​​​​​

• what is taskset

• isolcpus

Operating-System-Specific Tools​​​​​​​

• gdb

• conky

• vmstat

• mpstat

• iostat

• system tap

• top

Garbage Collection-Advanced Tuning ScenariosAdvance Tuning Scenarios-Part2

• JDK 5,6,7 defaults

• Default Flags

• Garbage Collection Data of Interest

Tuning GC For Throughput and Latency

Latency

• Old(Parallel)

• Perm

• Young (Parallel)

• Pset Configuration

Old (CMS)

• Tenuring Distribution

• Initiating Occupancy

• Common Scenarios

• Survivor Ratio

• Tenuring threshold

Througput

• (Parallel GC)

• CondCardmark

• Adaptive Sizing

• Tlabs

• Large Pages

• Numa

• Pset Configuration

CMS

• Concurrent Mode Failure

Monitoring GC

• Par New

• Parallel GC

• Safe Pointing

• Time Stamps

• Date Stamps

• System.GC

Advance Tuning Scenarios-Part1

• Monitoring the GC

• Conclusions

GC Tuning

• Tuning Parallel GC

• Tuning CMS

• Tuning the young generation

GC Tuning Methodology

• Deployment Model

• Choosing Runtime

• General GuideLines

• Data Model

Heap Sizing

• Factor Controlling Heap Sizing

MonitoringCtrl-Break Handler

• Deadlock Detection

• Thread Dump

• Heap Summary

jmap Utility

• Heap Histogram of Running Process

• Getting Information on the Permanent Generation

• Heap Histogram of Core File

• Heap Configuration and Usage

jps Utilityjhat Utility

• Instances Query

• Histogram Queries

• Standard Queries

• Heap Analysis Hints

• All Classes Query

• Object Query

• Where was this object allocated?

• Roots Query

• Instance Counts for All Classes Query

• New Instances Query

• What is keeping an object alive?

• All Roots Query

• Class Query

• Reachable Objects Query

• Custom Queries

jstack Utility

• Printing Stack Trace From Core Dump

• Printing a Mixed Stack

• Forcing a Stack Dump

jrunscript Utilityjsadebugd Daemonjstatd DaemonJMX

• Introduction

• Dynamic Mbeans

• Open Mbean

• Standard Mbeans

• JMX Remoting

• Advanced Features

• J2EE Management(optional)

• Model Mbean

jstat Utility

• Example of -gcoldcapacity Option

• Example of -gcnew Option

• Example of -gcutil Option

jinfo Utilityvisualgc ToolCPU Usage Profilers

Solaris Studio Analyzer (Linux and Solaris)

• stepping through assembly with source

• er_print utility

• stepping through call-stack (native and java)

• stepping through byte codes with source

• Associating hardware events with java code analyzer

• Collecting processor specific hardware events

• Collect command

Java Mission Control

• Enabling JFR

• Selecting JFR Events

• Java Flight recorder

Diagnostics and Analysis

Native Memory Best Practices

• Measuring Footprint

• NIO Buffers

• Minimizing Footprint

• Native Memory Tracking

• FootPrint

Integrating Signal and Exception Handling

• Reducing Signal Usage

• Console Handlers

• Signal Chaining

• Signal Handling on Solaris OS and Linux

• Alternative Signals

• Signal Handling in the HotSpot Virtual Machine

Reasons for Not Getting a Core FileDiagnosing Leaks in Native Code

• Crash in Compiled Code

• Tracking Memory Allocation With OS Support

• Using libumem to Find Leaks

• Tracking Memory Allocation in a JNI Library

• Tracking All Memory Allocation and Free Calls

• Sample Crashes

• Crash in Native Code

• Crash in VMThread

• Determining Where the Crash Occurred

• Crash due to Stack Overflow

• Using dbx to Find Leaks

• Crash in the HotSpot Compiler Thread

• Troubleshooting System Crashes

Developing Diagnostic Tools

• Java Platform Debugger Architecture

• java.lang.management Package

• Java Virtual Machine Tools Interface

Diagnosing Leaks in Java Language Code

• Obtaining a Heap Histogram on a Running Process

• -XX:+HeapDumpOnOutOfMemoryError Command-line

• Option

• jmap Utility

• Using the jhat Utility

• JConsole Utility

• Monitoring the Number of Objects Pending Finalization

• Obtaining a Heap Histogram at OutOfMemoryError

• HPROF Profiler

• NetBeans Profiler

• Creating a Heap Dump

Troubleshooting Hanging or Looping Processes

• Diagnosing a Looping Process

• Deadlock Detected

• No Thread Dump

• Deadlock Not Detected

• Diagnosing a Hung Process

Forcing a Crash DumpTroubleshooting Memory Leaks

• Crash Instead of OutOfMemoryError

• Meaning of OutOfMemoryError

• Detail Message: <reason> <stack> (Native method)</stack></reason>

• Detail Message: Java heap space

• Detail Message: request <size> bytes for <reason> Out of swap</reason></size>

• space?

• Detail Message: PermGen space

• Detail Message: Requested array size exceeds VM limit

Finding a Workaround

• Crash During Garbage Collection

• Class Data Sharing

• Crash in HotSpot Compiler Thread or Compiled Code

Direct Memory

• Avoiding GC for low latencies

• Why not C/C++

• Going Off-heap

• Advantages of Off-heap structures

• Disadvantages of Off-heap structures

Garbage Collection and Memory Architecture

• Heap Fragmentation

• GC Pros and Cons

• Object Size

• Algorithms

• Overview

• Performance

• GC Tasks

• Reachability

• Managing OutOfMemoryError

• Generational Spaces

• Measuring GC Activity

History

• Summary

• Old Space

• Young Space

• JVM 1.4, 5, 6

Advanced JVM ArchitectureTuning inlining

• MaxInlineSize

• InlineSmallCode

• MaxInline

• MaxRecursiveInline

• FreqInlineSize

Monitoring JIT

• Deoptimizations

• Backing Off

• PrintCompilation

• OSR

• Log Compilations

• Optimizations

• PrintInlining

Intrinsics

• Common intrinsics

Advanced JVM Architecture Part 1

• NUMA

• Inline caching

• Virtual method calls Details

• Virtual Machine Design

• Dynamic Compilation

• Large Pages

• Biased Locking

• Lock Coarsening

• Standard Compiler Optimizations

• Speculative Optimizations

• Escape Analysis

• Scalar Replacements

• Inlining DetailsVM Philosophy

Understanding and Controlling JVM Options

• DoEscapeAnalysis

• AggressiveOpts

CallSites

• Polymorphic

• BiMorphic

• MegaMorphic

• MonoMorphic

HotSpot

• Client

• Server

• Tiered

Advanced JVM Architecture-Part 2

• JIT

• Mixed mode

• Golden Rule

• Profiling

• Optimizations

Memory AnalysisCore/Heap dumps Analyzerjdb Utility

• Attaching to a Process

• Attaching to a Core File on the Same Machine

• Attaching to a Core File or a Hung Process from a Different Machine

JConsole Utility Serviceability Agent(SA)

• Cache Dump

• Stepping Through heap

• Class Browser

• Compute reverse pointers

• Stepping through NON Heap

• Deadlock detection

• Value in code cache

• Code Viewer

Java VisualVMHPROF - Heap Profiler

• CPU Usage Sampling Profiles ( cpu=samples)

• CPU Usage Times Profile ( cpu=times)

• Heap Dump ( heap=dump)

• Heap Allocation Profiles ( heap=sites)

NIO 2.0

• File System Change Notification

• Multicasting

• File and Directories

• Symbolic Links

• Watch Service API

• Metadata File Attributes

• Two Security models

• FileVisitor Class

• Working with path

• SPI Package

• Asynchronous IO with Socket and File

Concurrent Data Structures

Java Memory Model(JMM)

• Real Meaning and effect of synchronization

• Volatile

• Sequential Consistency would disallow common optimizations

• The changes in JMM

• Final

Shortcomings of the original JMM

• Finals not really final

• Prevents effective compiler optimizations

• Processor executes operations out of order

• Compiler is free to reorder certain instructions

• Cache reorders writes

• Old JMM surprising and confusing

Instruction Reordering

• What is the limit of reordering

• Programmatic Control

• super-scalar processors

• heavily pipelines processors

• As-if-serial-semantics

• Why is reordering done

Cache Coherency

• Write-back Caching explained

• What is cache Coherence.

• How does it effect java programs.

• Software based Cache Coherency

• NUMA(Non uniform memory access)

• Caching explained

• Cache incoherency

New JMM and goals of JSR-133

• Simple,intuitive and, feasible

• Out-of-thin-air safety

• High performance JVM implementations across

• architectures

• Minimal impact on existing code

• Initialization safety

• Preserve existing safety guarantees and type-safety

Highly Concurrent Data Structures-Part1Weakly Consistent Iterators vs Fail Fast IteratorsConcurrentHashMap

• Structure

• remove/put/resize lock

• Almost immutability

• Using volatile to detect interference

• Read does not block in common code path

Applying Thread PoolsConfiguring ThreadPoolExecutor

• Thread factories

• corePoolSize

• Customizing thread pool executor after construction

• Using default Executors.new* methods

• Managing queued tasks

• maximumPoolSize

• keepAliveTime

• PriorityBlockingQueue

Saturation policies

• Discard

• Caller runs

• Abort

• Discard oldest

Sizing thread pools

• Examples of various pool sizes

• Determining the maximum allowed threads on your operating system

• CPU-intensiv vs IO-intensive task sizing

• Danger of hardcoding worker number

• Problems when pool is too large or small

• Formula for calculating how many threads to use

• Mixing different types of tasks

Tasks and Execution Policies

• Long-running tasks

• Homogenous, independent and thread-agnostic tasks

• Thread starvation deadlock

Extending ThreadPoolExecutor

• terminate

• Using hooks for extension

• afterExecute

• beforeExecute

Parallelizing recursive algorithms

• Using Fork/Join to execute tasks

• Converting sequential tasks to parallel

Common Issues with thread

• Uncaught Exception Handler

• problem with stop

• Dealing with InterruptedStatus

Canned Synchronizers

• Semaphore

• Latches

• SynchronousQueue

• Future

• Exchanger

• Synchronous Queue Framework

• Mutex

• Barrier

Producer Consumer(Basic Hand-Off)Why wait-notify require Synchronization

• notifyAll used as work around

• Structural modification to hidden queue by wait-notify

• locking handling done by OS

• use cases for notify-notifyAll

• Hidden queue

• design issues with synchronization

Advanced Class-loading

• Understanding visibility rules

• Advantages of Peer Class-loading

• Hot Loading

• IllegalAccessException

• ClassCastException

• Peer Class-loading

• Understanding delegation rules

• LinkageError

• Problems with these rules.

Class-loading

• Common Class loading Issues

• Changing the rules of default class visibility

• Class Loading Basics

• Introduction

• Diagnosing and resolving class loading problems

• Custom Class Loaders

• Class visibility

NIOCharacter Streams Encoding

• Other Charsets - ISO 8859

• Big / Little Endian

• Forms of Unicode

• 32-bit Characters

• Code Points

• Charset Class

• Other Encodings

• The Unicode Standard

• Encoders and Decoders

Java New IO Package

• Non-Blocking Operations

• Buffers Advantages

• Selectors

• Channels

• Allocating Buffers

• Motivation for Using

• Memory Mapped Files

• Working with Buffers

NIO Uses

• Event Driven Architecture