Many Cores Java - Session One: Threads and Threads
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Aims to introduce some basic concurrency design concepts by starting with a single core. Takes a top down approach. If you're looking for a guide to implementation, read anything and everything written by Doug Lea. Exercises available at https://github.com/RobertBurrellDonkin/kata-manycore-threadsandthreads
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Azul Systems. Are you interested in learning what a Java Virtual Machine (JVM) is and what it does for your Java applications? This presentation will provide insight into the inner workings of a Java Virtual Machine and some drill down on what compilers and garbage collectors do, so that you don't have to worry about it while programming your Java application. In particular, you will learn about common optimizations, well established garbage collection algorithms, and what the current biggest challenge with Java scalability is today.
Java Memory Consistency Model - concepts and context
Java Memory Consistency Model is a difficult topic.
It's useful in making sure that multi-threaded programs on multi-threaded cores will interact with each other (and through memory) in a consistent manner.
It's specification is damn hard (even according to folks with lots of concurrent experience, like Doug Lea) to read, understand and routinely follow without error.
This presentation talks about some fallacies surrounding memory model, explains it, offers definitions and reasons for it's existence. It ain't deep, it's more entry level stuff.
Threads in Java
Threads allow programs to perform multiple tasks concurrently. A thread is a single sequence of execution within a program. Multithreading refers to multiple threads running within a single program. Threads share program resources but have their own call stack and local variables. Threads are created by extending the Thread class or implementing the Runnable interface. Synchronization is needed when multiple threads access shared resources concurrently to prevent race conditions. The wait() and notify() methods enable threads to cooperate by pausing and resuming execution.
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The document summarizes Google's Bigtable storage system, which provides a structured storage layer for large distributed data sets. Bigtable stores data as a sparse, distributed, multidimensional sorted map. It is built using the Google File System for storage, Chubby for locking, and provides a simple "get/put/delete" interface for accessing rows and columns. Bigtable tables are sharded into tablets, distributed across servers, and data is stored in immutable Sorted String Tables (SSTables).
JAVA NIO
- Java NIO provides non-blocking and asynchronous network input/output that can help address performance issues with Java IO such as blocking behavior and thread overhead.
- Key aspects of Java NIO include direct buffers to reduce copying, channel-based IO to support scatter/gather operations, and selectors for asynchronous non-blocking IO across multiple channels.
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Tutorial4 Threads
Threads are lightweight processes that exist within a process and share most of the process resources like memory and file descriptors. Threads have their own independent flow of control and maintain their own stack pointer, registers, and scheduling properties. The pthreads API provides functions for creating and managing threads in UNIX/Linux environments. Pthreads allow creating threads that execute concurrently and share resources.
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Multi-core architectures
This document summarizes multi-core computer architectures. It discusses how single-core CPUs are being replaced by multi-core chips that contain multiple processor cores on a single die. Each core can run threads in parallel for improved performance. The cores share the same memory and socket. Operating systems see each core as a separate processor. Issues around cache coherence and programming for multi-core architectures are also covered at a high level.
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IT MATCH: Vastgoedfinanciering voor zelfstandigen / freelancers in België
IT MATCH: Vastgoedfinanciering voor zelfstandigen / freelancers in België
Java Memory Consistency Model - concepts and context
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Agenda:
In this talk we will present various locking mechanisms implemented in the linux kernel.
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Speaker:
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More from Robert Burrell Donkin
Threads and Threads
Pre-emptive multi-tasking operating systems use involuntary context switching to provide the illusion of parallel processes even when the hardware supports only a single thread of execution. This allows for liveliness, responsiveness, and sometimes performance by time-slicing the CPU between processes through rapid context switching, where the execution state is stored and restored. While context switching was once expensive, cache improvements have reduced the cost so it is usually low compared to other operations, though excessive context switching can still be expensive.
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This document discusses data locality and scaling algorithms to large datasets. It notes that as more processors are added, the problem size should also scale up according to Gustafson's Law. Map-Reduce platforms provide benefits like fault tolerance, orchestration, and redundant storage that help process terabytes and petabytes of data by adding new nodes smoothly. The conclusion recommends adopting an appropriate architecture now to enable processing of big data by adding cores or computers in the future.
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A brief introduction to Retrospectives. From an Agilist perspective. Complete with notes (at the end of the main presentation.
Original http://tinyurl.com/5wfs8yy
License
Robert Burrell Donkin http://robertburrelldonkin.name created “Agile Retrospectives in
Ten Slides” in 2011.
This work is licensed under the Creative Commons Attribution 3.0 Unported License. To
view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/ or send a
letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California,
94105, USA.
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Many Cores Java - Session One: Threads and Threads
- 1. Threads and Threads session one starting with a single core copyright 2013 Robert Burrell Donkin robertburrelldonkin.name this work is licensed under a Creative Commons Attribution 3.0 Unported License
- 2. Threads, Threads and Processes from the ● hardware perspective ○ a thread is a serial code sequence ● software perspective ○ a thread abstracts a serial code sequence ● operating system perspective ○ a process abstracts an application instance
- 3. Multi-tasking a Single Core ● on a single core ○ a multitasking operating system ■ uses scheduling ■ to create the illusion of parallelism ● a software platform may also ○ use scheduling to create the illusion of parallelism ○ but then this is more often called multi-threading
- 4. Approaches to Multi-Tasking ● cooperative (or voluntary) multi-tasking ○ time-sharing ○ background processing ○ early Apple PCs ○ now rarely used ● pre-emptive multi-tasking ○ time-slicing ○ Windows 95 PCs ○ now almost universal
- 5. Why Multi-Task...? ● liveliness ● responsiveness ○ (to people) ● performance ○ (sometimes)
- 6. Context Switch ● a context switch ○ stores the current execute state, and ○ restores an execution state from storage ● from a CPU perspective ○ this is an expensive operation ● but is often cheap in comparison
- 7. Caches, Caches, Caches ● Moore's Law ○ the number of transistors doubles every 2 years ● but ○ diminishing returns from longer pipelines ○ popularity of multi-tasking ● so more and bigger caches ● so context switching cost now usually low ● but scales in a non-linear fashion ● excessive context switching expensive
- 8. Pre-emptive multi-tasking operating systems use involuntary context switching to provide the illusion of parallel processes even when the hardware supports only a single thread of execution. Take Away
- 9. Break Out ● Exercises ○ https://github.com/RobertBurrellDonkin/kata-manycore- threadsandthreads ● Try ○ On Windows ■ perfmon ■ typeperf ○ On Linux ■ vmstat ■ iostat ■ mpstat