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A synchronization primitive, which limits access to a given resource, such as a limited number of database connections, open files, or network connections.
## Example
~~~ ruby
require 'async'
require 'async/semaphore'
require 'net/http'
Sync do
# Only allow two concurrent tasks at a time:
semaphore = Async::Semaphore.new(2)
# Generate an array of 10 numbers:
terms = ['ruby', 'python', 'go', 'java', 'c++']
# Search for the terms:
terms.each do |term|
semaphore.async do |task|
Console.info("Searching for #{term}...")
response = Net::HTTP.get(URI "https://www.google.com/search?q=#{term}")
Console.info("Got response #{response.size} bytes.")
end
end
end
~~~
### Output
~~~
0.0s info: Searching for ruby... [ec=0x3c] [pid=50523]
0.04s info: Searching for python... [ec=0x21c] [pid=50523]
1.7s info: Got response 182435 bytes. [ec=0x3c] [pid=50523]
1.71s info: Searching for go... [ec=0x834] [pid=50523]
3.0s info: Got response 204854 bytes. [ec=0x21c] [pid=50523]
3.0s info: Searching for java... [ec=0xf64] [pid=50523]
4.32s info: Got response 103235 bytes. [ec=0x834] [pid=50523]
4.32s info: Searching for c++... [ec=0x12d4] [pid=50523]
4.65s info: Got response 109697 bytes. [ec=0xf64] [pid=50523]
6.64s info: Got response 87249 bytes. [ec=0x12d4] [pid=50523]
~~~
|
