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Section 3
Threading and Locking
+ Section 3 Threading and Locking + Definitions What is a thread? - - PowerPoint PPT Presentation
+ Section 3 Threading and Locking + Definitions What is a thread? - - PowerPoint PPT Presentation
+ Section 3 Threading and Locking + Definitions What is a thread? + Definitions What is a thread? A single flow of control with a process + Definitions What is a thread? A single flow of control with a process Why use threads? + Definitions
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SLIDE 3
+Definitions
What is a thread? A single flow of control with a process
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+Definitions
What is a thread? A single flow of control with a process Why use threads?
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+Definitions
What is a thread? A single flow of control with a process Why use threads? Exploit latency, concurrency
Event-driven software
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+Dangers
What could go wrong?
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+Dangers
What could go wrong? Race Conditions
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+Dangers
What could go wrong? Race Conditions How do we fix this?
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+Dangers
What could go wrong? Race Conditions How do we fix this? Locking
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+Definitions
What is a lock?
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+Definitions
What is a lock?
Serializes access to some critical region of code or data Used to enforce mutual exclusion concurrency control
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+Definitions
What is a lock?
Serializes access to some critical region of code or data Used to enforce mutual exclusion concurrency control Locks need help from hardware
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+Definitions
What is a lock?
Serializes access to some critical region of code or data Used to enforce mutual exclusion concurrency control Locks need help from hardware Different kinds of locks
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+Dangers
What could go wrong?
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+Dangers
What could go wrong? Impacts Performance
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+Dangers
What could go wrong? Impacts Performance
Hard to debug
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+Dangers
What could go wrong? Impacts Performance
Hard to debug Deadlocks
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+Dangers
What could go wrong? Impacts Performance
Hard to debug Deadlocks
How do we fix this?
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+Dangers
What could go wrong? Impacts Performance
Hard to debug Deadlocks
How do we fix this? Punt (if collisions aren’t our problem)
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+Dangers
What could go wrong? Impacts Performance
Hard to debug Deadlocks
How do we fix this? Punt (if collisions aren’t our problem)
Resource hierarchy/Conductor/Chandy-Misra
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+Using Threads
Creation Termination Detachment and Joining Self and Equal
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+Using Threads
Thread (class) Runnable (interface) ForkJoin ThreadPools/Executor Services
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+Project 0 Review
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+Project 1 Suggestions
John’s Suggestion
One thread for listening (waiting for server probes) One thread for keyboard input that handles server communication initiated by keyboard input One thread for periodic re-registration
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+Project 1 Reminders
John’s Suggestion
One thread for listening (waiting for server probes) One thread for keyboard input that handles server communication initiated by keyboard input One thread for periodic re-registration
Remember Terminate cleanly
You need to re-register Modularity
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+Questions?
Java:
http://docs.oracle.com/javase/tutorial/essential/concurrency/index.html http://docs.oracle.com/cd/E13150_01/jrockit_jvm/jrockit/geninfo/diagnos/ thread_basics.html