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Added Wait Group section.

Rick Beton 2015-03-19 14:52:22 +00:00
parent b71a01c940
commit 901b5a65e5
1 changed files with 9 additions and 3 deletions
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10
MutexOrChannel.md

@ -12,12 +12,18 @@ A common Go newbie mistake is to over-use channels and goroutines just because i
As a general guide, though:
| **Channel** | **Mutex**|
|:------------|:---------|
| **Channel** | **Mutex** |
|:------------|:----------|
| passing ownership of data,<br />distributing units of work,<br /> communicating async results | caches,<br />state |
If you ever find your sync.Mutex locking rules are getting too complex, ask yourself whether using channel(s) might be simpler.
## Wait Group
Another important category is sync.WaitGroup. These allow co-operating goroutines to collectively wait for a threshold event before proceeding independently again. This is useful typically in two cases. Firstly, when 'cleaning up', a sync.WaitGroup can be used to ensure that all goroutines - including the main one - wait before all terminating at once.
The second more general case is of a cyclic algorithm that involves independent work by the goroutines, then waiting on a barrier before proceeding independently. Data might be exchanged at the barrier event. This strategy is the basis of [Bulk Synchronous Parallelism](https://en.wikipedia.org/wiki/Bulk_synchronous_parallel) (BSP).
## More Info
* Channels in Effective Go: http://golang.org/doc/effective_go.html#channels