Question 1

Hardware

Accepted Answer

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

Question 2

Operating System

Accepted Answer

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

Question 3

Java Virtual Machine

Accepted Answer

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: (Native method) • Detail Message: Java heap space • Detail Message: request bytes for Out of swap • 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)

Question 4

Java Language Tuning

Accepted Answer

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

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.

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