It Security Chapter 4

Pico Java

A modified version of JAVA used to write IOT's?

simplify code, increase efficency

A thread can ____ and ____

belonging to the same process, code section, data section, other OS resources

A thread shares with other threads...

single thread

A traditional/heavyweight process has a

pthread.h (header)

All pthreads must include in their program what?

Signal Handling

Another issue of threading is _____ _____.

POSIX

GCDs thread pool is composed of _______ threads?

Mac OS X

Grand Central Dispatch (GCD) is for what system?

Amdahl's Law

Identifies performance gains from adding additional cores to an application that has both serial and parallel components

one client at a time slowing down the application

If the server web ran as a traditional single-threaded process it would be able to service only

a separate thread that listens for client request, a new thread to service the request and resume listening for additional request

If the web-server process is multithreaded the server will create _____. When a request is made rather than creating another process the server creates______

allows multiple threads to run in parallel on multiprocessors

One-to-One-Model

parallel regions

OpenMP identifies ______ _______ as blocks of code that may run in parallel.

Linux, Windows, Mac OSX

OpenMP is available to ______,________,and__________ systems.

threads run in parallel on different processing cores. In a single threaded process can run only one process regardless of how many are available.

Scalability is when?

default, user

every signal has a _______ signal handler that the kernel runs when handling the signal. this can be overriden by a _____ defined signal handler that is called to handle the signal.

multithreaded

kernels are

Starvation Philosopher

no matter how you design the code their may be a condition of starvation starvation mode: not enough resources to finish their tasks Problem in OS no deadlock but starvation is possible

fork (), exec()

one of the issues of threading is ______ and _____ system calls.

serial, concurrent

what are the two kinds of dispatch queues?

UNIX, synchronously, asynchronously

A signal is used in _____ systems to notify a process that a particular event has occured. A signal can be received either ____________________ or ___________________.

Solaris, 30, context switching, 5

Economy example: In ______ creating a process is about ______ times slower than creating a thread and _______ _____ is about ____ times slower

context switch, process

Economy? creating threads and ________ ________ them saves more memory and resources than creating a whole new ______.

one process that contains multiple threads

In the web server it is generally more efficient to use

JVM, Windows, Linux, Max OS, Android

Java threads are available for any system that provides an _____ including ______, _______, ________,_______.

free memory in the system

Linux uses a kernel thread for managing the amount of _______

many user threads to one but cannot take advantage of multicore processor

Many-to-One-Model

develop as many user threads as needed, kernel threads can run in parallel on a multiprocessor

Many-to-many model?

2, 8

Modern Intel CPU supports __ threads per core. Oracle T4 CPU supports ___ threads per core

multithreaded

Most modern applications are

place multi computing cores on a single chip. Each core appears as a separate process to the OS

Multi core or multiprocessing systems are?

Dividing activities, Balance,Data splitting, Data dependency Testing, debugging

Multicore or multiprocessing system puts pressure on programmers challenges include...

a process can preform more than one task simultaneously

Parallelism is when

Kernel Design

Process communication is most important part of

heavyweight, lightweight

Process creation is _____ while thread creation is ________

synchronization, specification, implementation

Pthreads refers the POSIX standard defining an API for thread creation and _______. This is a ______ for thread behavior not an ______.

multithreaded

RPC servers are usually what?

it allows an application to have several different threads of activity withing the same address space, the technique of sharing would have to arranged by the programer

Resource Sharing? Since threads automatically share memory and the resources of the process ______. If it was a process was single threaded then____

A program can continue running if it is multithreaded even if part of it is blocked or performing a lengthy operation. If it was single threaded you would not be able to do other stuff within the application if it was single threaded until the 1st process was done

Responsiveness has to do with when?

interrupt handling

Solaris kernel has a set of threads specifically for

Responsiveness, resource sharing, economy, scalability

The benefits of multithreaded programming can be broken down into four major catagories?

allocates memory and initializes a new thread in the JVM, it calls the run () method making the thread able to run by the JVM

The start () method creates the new thread in Java it does 2 things?

entirely in user space with no kernel support this results in a local call and not a system call, kernel level supported by OS results in system call

There are two different ways to implement a thread library?

POSIX pthreads, Windows, Java

Three main libraries are in use today?

PCB (Process Control Block)

To terminate the process you just have to delete the...

Linux, Windows

What 2 systems use the one-to-one model?

linux, mac os x, solaris, Windows (third party)

What are the systems that use pthreads?

create a new class that is from the THREAD class and to override its run() method, define a class that implements the runnable interface

What are the two ways to create a thread in Java?

asynchronous and synchronous threading

What are two general strategies for creating multiple threads?

A parent thread creates one or more children and then wait for all of its children to terminate before it resumes the so called fork-join stratagy.

What does synchronous threading do?

is a set of compiler directives as well as an API for programs written in C, C++, or FORTRAN that provides support for parallel programming in shared memory environments

What is OpenMP?

Remote Procedure call, allows interprocess communication by providing a communication mechanism

What is a RPC? And what does it do?

assigns a block to an available thread from the thread pool it manages

What is a dispatch queue?

provides programmer with an API for creating and managing threads

What is a thread library?

number of threads at process startup and place them in a pool where they sit and wait for work

What is a thread pool?

A parent creates a child and resumes execution so that the parent and child execute concurrently (Doesnt matter when child terminates since they run independently)

What is asynchronous threading do?

distributing subsets of the same data across multiple computing cores and performing the same operation on each core

What is data parallelism?

A thread library available for Solaris Systems and adopted in early versions of Java, many to one

What is green threads? What thread model does it use?

distributing tasks (threads) not data across multiple computing cores

What is task parallelism?

User threads are managed without kernel support. Kernel threads are are supported by OS.

What is the difference between user and kernel threads?

allows a user level thread to be bound to a kernel level thread and multiplexes many user level threads to a smaller or equal number of kernel threads

What is the two level model?

separate thread, requests

When a RPC server gets a message it services it with a _____. This allows many _____ to happen at once.

supports more than one task by allowing all the tasks to make progress

concurrency is when

Windows, Linux, Mac OS X, Solaris

Which four programs support Kernel threads?

C

Windows is written in ____ code?

thread ID, program counter, register set, stack

a thread has ...