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Added Wait Group section.

Rick Beton 2015-03-19 14:52:22 +00:00
parent b71a01c940
commit 901b5a65e5
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12
MutexOrChannel.md

@ -12,13 +12,19 @@ A common Go newbie mistake is to over-use channels and goroutines just because i
As a general guide, though: 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 | | 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. 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 ## More Info
* Channels in Effective Go: http://golang.org/doc/effective_go.html#channels * Channels in Effective Go: http://golang.org/doc/effective_go.html#channels
* The sync package: http://golang.org/pkg/sync/ * The sync package: http://golang.org/pkg/sync/