解决了这么几个问题

• Does HTM obviate the need for crafty lock-free index designs? No.

• How does HTM differ from lock-free index designs?

• Given that lock-free designs are still relevant, can HTM help simplify lock-free design techniques while maintaining good performance? Yes.

HTM

Transactional memory

ease the burden (a tedious and error prone task leading to deadlocks and race conditions) by delegating conflict detection and resolution from the developer to the system.

Hardware Transactional Memory

a best-effort model, optimistic concurrency.

specification

• ordered（ascending）
• no duplicated key

features

• non-blocking
• linearizable
• compare-and-swap based

仅使用一个cas的缺陷

• insert

• delete

对于只有一个insert或者一个delete的情况，没有问题会出现。

Memory model basics

two aspects:

• the basic structural aspects;
• the concurrency aspects.

Objects and memory location

C++程序中所有的数据都是由object组成，object是"a region of storage"。一个对象存储在一个或多个memory location。

Lecture 3: Big Data, Hardware Trends, and Apache Spark and Lecture 4: Spark Essentials

The Big Data Problem

• Growing data sources
• Storage getting cheapper
• But stalling CPU and storage bottlenecks

Hardware for Big Data

Problems with cheap hardware

• Failures
• Network
• Uneven performance

What’s Hard About Cluster Computing

• Divide work across machines
  • Must consider network, data locality
  • Moving data may be veay expensive
• Deal with failures

Spark Essentials

PySpark

A Spark program consists of two programs, a driver program and a workers program.

Basic

Creating Named Sessions

1

tmux new-session -s basic

or

1

tmux new -s basic

Detaching Sessions

CTRL-b, then d

Reattaching to Existing Sessions

1

tmux new-session -s basic

or

1

tmux ls

1. If there is only session, then tmux attach.
2. If there are multiple sessions, then tmux attach -t second_session. BTY, you can also use this when you only have one session.

Killing Sessions

• In sesssion, use exit.
• Kill specific session when not in session,

1

tmux kill-session -t basic

BTY, if there is no sessions, after typing tmux ls, you will get

If you want some specific package not to be processed（keep the current version with the current status whatever that is）, you can hold it.

hold

1

echo "package_name hold" | dpkg --set-selections

unhold

1

echo "package_name install" | dpkg --set-selecions

References

1. The Debian GNU/Linux FAQ Chapter 7 - Basics of the Debian package management system