Getting started
1) make buffered channel
sem := make(chan int, 10)
2) in synchronous process, send some variable to buffered channel (this step called acquire)
sem <- i
3) in asynchronous process, release variable from buffered channel (this step called release)
<- sem
Result from log
start process [9]
start process [0]
start process [7]
start process [6]
start process [3]
start process [2]
start process [4]
start process [8]
start process [1]
start process [5] <- 10 processes start concurrency
end process [0] 0.0001 seconds
start process [10] <- process 10 start after process 0 end
end process [2] 4.0014 seconds
end process [1] 4.0012 seconds
start process [12]
start process [11] <- process 11, 12 start after process 1, 2 end
end process [3] 5.0011 seconds
start process [13]
end process [4] 0.0001 seconds
start process [14]
end process [5] 6.0014 seconds
start process [15]
end process [6] 1.0011 seconds
start process [16]
end process [7] 8.0013 seconds
start process [17]
...
Remark
Standard package
golang.org/x/sync/semaphore
Code
package main
import (
"fmt"
"math/rand"
"time"
)
const (
MAX_CONCURRENT = 10 // Allow max concurrent
TOTAL_PROCESSES = 1000 // Total loop count
MAX_RANDOM_SECONDS = 20
)
func main() {
sem := make(chan int, MAX_CONCURRENT)
for i := range TOTAL_PROCESSES {
sem <- i // *** send i to buffered channel. If channel sem full, it blocked for loop.
go func(i int) {
start := time.Now()
fmt.Printf("start\tprocess\t[%d]\n", i)
defer func() {
// <- sem will release a value, so sem channel will available for next value
fmt.Printf("end\tprocess\t[%d]\t %.4f seconds\n", <-sem, time.Since(start).Seconds())
}()
iv := rand.Intn(MAX_RANDOM_SECONDS) * int(time.Second)
time.Sleep(time.Duration(iv))
}(i)
}
}
start process [0]
start process [9]
start process [5]
start process [6]
start process [7]
start process [8]
start process [2]
start process [1]
start process [3]
start process [4]
start process [10]
end process [0] 3.0013 seconds
start process [11]
end process [1] 2.0012 seconds
start process [12]
end process [2] 6.0012 seconds
end process [3] 9.0012 seconds
start process [13]
end process [4] 5.0008 seconds
start process [14]
end process [5] 12.0012 seconds
end process [6] 12.0012 seconds
start process [16]
start process [15]
start process [17]
end process [7] 14.0012 seconds
end process [8] 16.0012 seconds
end process [9] 16.0012 seconds
start process [19]
end process [10] 0.0001 seconds
start process [20]
start process [18]
end process [11] 17.0012 seconds
start process [21]
end process [12] 18.0002 seconds
start process [22]
end process [14] 8.0012 seconds
end process [13] 4.0010 seconds
start process [24]
start process [23]
end process [15] 15.0011 seconds
start process [25]
start process [26]
end process [16] 13.0011 seconds
end process [17] 15.0005 seconds
start process [27]
end process [18] 0.0000 seconds
start process [28]
end process [19] 5.0010 seconds
end process [20] 4.0011 seconds
start process [29]
start process [30]
end process [21] 2.0005 seconds
end process [22] 12.0011 seconds
start process [31]
start process [32]
end process [23] 6.0002 seconds
start process [33]
end process [24] 1.0002 seconds
start process [34]
end process [25] 9.0011 seconds
start process [35]
end process [26] 1.0002 seconds
start process [36]
end process [27] 12.0011 seconds
start process [37]
end process [28] 3.0007 seconds
start process [38]
end process [29] 13.0011 seconds
start process [39]
end process [30] 19.0012 seconds
start process [40]
end process [31] 8.0010 seconds
start process [41]
end process [32] 8.0011 seconds
start process [42]
end process [33] 8.0001 seconds
start process [43]
end process [34] 11.0010 seconds
end process [35] 13.0001 seconds
start process [45]
start process [44]
end process [36] 2.0009 seconds
start process [46]
end process [37] 1.0002 seconds
start process [47]
end process [38] 8.0011 seconds
start process [48]
end process [39] 2.0011 seconds
start process [49]
end process [40] 4.0011 seconds
start process [50]
end process [41] 6.0011 seconds
start process [51]
start process [52]
end process [42] 19.0011 seconds
end process [43] 15.0011 seconds
start process [53]
end process [44] 0.0000 seconds
start process [54]
end process [45] 17.0004 seconds
start process [55]
end process [46] 19.0006 seconds
start process [56]
start process [57]
end process [47] 15.0011 seconds
end process [48] 3.0011 seconds
start process [58]
end process [49] 17.0011 seconds
start process [59]
end process [50] 18.0011 seconds
start process [60]
end process [51] 0.0001 seconds
start process [61]
end process [52] 11.0001 seconds
end process [53] 18.0004 seconds
start process [63]
start process [62]
end process [54] 19.0011 seconds
start process [64]
start process [65]
end process [55] 19.0002 seconds
end process [56] 16.0006 seconds
start process [66]
end process [57] 11.0001 seconds
start process [67]
end process [58] 12.0001 seconds
start process [68]
end process [59] 18.0011 seconds
start process [69]
end process [60] 9.0002 seconds
start process [70]
end process [61] 6.0011 seconds
start process [71]
end process [63] 7.0006 seconds
end process [62] 8.0011 seconds
start process [73]
start process [72]
end process [64] 13.0011 seconds
start process [74]
end process [65] 15.0006 seconds
start process [75]
end process [66] 17.0001 seconds
start process [76]
end process [67] 3.0002 seconds
start process [77]
end process [68] 15.0011 seconds
start process [78]
start process [79]
end process [69] 14.0007 seconds
end process [70] 6.0006 seconds
end process [71] 11.0012 seconds
start process [81]
start process [80]
end process [72] 11.0011 seconds
start process [82]
end process [73] 4.0003 seconds
start process [83]
end process [74] 11.0008 seconds
end process [75] 15.0011 seconds
start process [85]
start process [84]
end process [76] 2.0011 seconds
start process [86]
end process [77] 6.0009 seconds
start process [87]
end process [78] 1.0011 seconds
start process [88]
end process [79] 6.0009 seconds
start process [89]
end process [80] 6.0011 seconds
end process [81] 11.0008 seconds
start process [91]
start process [90]
start process [92]
end process [82] 18.0011 seconds
end process [83] 16.0012 seconds
start process [93]
end process [84] 4.0002 seconds
start process [94]
end process [85] 9.0011 seconds
start process [96]
start process [95]
start process [97]
end process [86] 11.0003 seconds
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