README
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Channels
Channels allow goroutines to communicate with each other through the use of signaling semantics. Channels accomplish this signaling through the use of sending/receiving data or by identifying state changes on individual channels. Don't architect software with the idea of channels being a queue, focus on signaling and the semantics that simplify the orchestration required.
Design Guidelines
- Learn about the design guidelines for channels.
Diagrams
How an unbuffered channel works.
How a buffered channel works.
Links
Channel Communication
http://blog.golang.org/share-memory-by-communicating
http://www.goinggo.net/2014/02/the-nature-of-channels-in-go.html
A Retrospective on SEDA - Matt Welsh
Buffer Bloat - 2011
- Large buffers prevent timely notification of back pressure.
- They defeat your ability to reduce back pressure in a timely matter.
- They can increase latency not reduce it.
- Use buffered channels to provide a way of maintaining continuity.
- Don't use them just for performance.
- Use them to handle well defined bursts of data.
- Use them to deal with speed of light issues between handoffs.
Bufferbloat: Dark Buffers in the Internet
Buffer Bloat Videos
Code Review
Unbuffered channels - Tennis game (Go Playground)
Unbuffered channels - Relay race (Go Playground)
Buffered channels - Retrieving results (Go Playground)
Timer channels and Select (Go Playground)
Advanced Code Review
Channel communication ordering (Go Playground)
Exercises
Exercise 1
Write a program where two goroutines pass an integer back and forth ten times. Display when each goroutine receives the integer. Increment the integer with each pass. Once the integer equals ten, terminate the program cleanly.
Template (Go Playground) | Answer (Go Playground)
Exercise 2
Write a program that uses a fan out pattern to generate 100 random numbers concurrently. Have each goroutine generate a single random number and return that number to the main goroutine over a buffered channel. Set the size of the buffer channel so no send every blocks. Don't allocate more buffers than you need. Have the main goroutine display each random number is receives and then terminate the program.
Template (Go Playground) | Answer (Go Playground)
All material is licensed under the Apache License Version 2.0, January 2004.
Directories
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| Path | Synopsis |
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advanced
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example1
Sample program to show the order of channel communication for unbuffered, buffered and closing channels based on the specification.
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Sample program to show the order of channel communication for unbuffered, buffered and closing channels based on the specification. |
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Sample program to show how to use an unbuffered channel to simulate a game of tennis between two goroutines.
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Sample program to show how to use an unbuffered channel to simulate a game of tennis between two goroutines. |
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Sample program to show how to use an unbuffered channel to simulate a relay race between four goroutines.
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Sample program to show how to use an unbuffered channel to simulate a relay race between four goroutines. |
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This sample program demonstrates how to use a buffered channel to receive results from other goroutines in a guaranteed way.
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This sample program demonstrates how to use a buffered channel to receive results from other goroutines in a guaranteed way. |
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This sample program demonstrates how to use a channel to monitor the amount of time the program is running and terminate the program if it runs too long.
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This sample program demonstrates how to use a channel to monitor the amount of time the program is running and terminate the program if it runs too long. |
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exercises
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exercise1
Write a program where two goroutines pass an integer back and forth ten times.
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Write a program where two goroutines pass an integer back and forth ten times. |
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exercise2
Write a program that uses a fan out pattern to generate 100 random numbers concurrently.
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Write a program that uses a fan out pattern to generate 100 random numbers concurrently. |
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template1
Write a program where two goroutines pass an integer back and forth ten times.
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Write a program where two goroutines pass an integer back and forth ten times. |
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template2
Write a program that uses a fan out pattern to generate 100 random numbers concurrently.
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Write a program that uses a fan out pattern to generate 100 random numbers concurrently. |