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| package main | |
| //#include <unistd.h> | |
| import "C" | |
| import ( | |
| "context" | |
| "log" | |
| "math/rand" | |
| "runtime" | |
| "sync" | |
| "time" | |
| ) | |
| /////////////////////////////////// | |
| // Application | |
| /////////////////////////////////// | |
| func main() { | |
| var wg sync.WaitGroup | |
| workersNum:=1000 // 10000 | |
| for i := 0; i <= workersNum; i++ { | |
| wg.Add(1) | |
| go func() { | |
| defer wg.Done() | |
| worker() | |
| }() | |
| } | |
| for { | |
| PrintMemUsage() | |
| time.Sleep(30*time.Second) | |
| } | |
| wg.Wait() | |
| } | |
| func worker() { | |
| for i := 0; i < 100000; i++ { | |
| // http.Get with Second timeout | |
| ctx, ctxCancel := context.WithTimeout(context.Background(), time.Second) | |
| doSmth(ctx) | |
| ctxCancel() | |
| } | |
| } | |
| /////////////////////////////////// | |
| // CGO resolver emulation | |
| /////////////////////////////////// | |
| // see net.go var threadLimit chan struct{} | |
| var threadsLimiter chan int | |
| func init() { | |
| threadsLimiter = make(chan int, 500 /*OS threads limit*/) | |
| } | |
| // see go/src/net/cgo_unix.go | |
| // func cgoIPLookup & cgoLookupIPCNAME | |
| func cgoCall(res chan struct{}) { | |
| threadsLimiter <- 1 | |
| defer func() { | |
| <-threadsLimiter | |
| }() | |
| t := uint(rand.Int() % 100) | |
| C.sleep(C.uint(t)) // ~ C.getaddrinfo | |
| close(res) | |
| } | |
| // see cgo_unix.go: func cgoLookupIP | |
| func doSmth(ctx context.Context) bool { | |
| res := make(chan struct{}) | |
| go cgoCall(res) // <---- goroutine leak (actually, there is no leak, we just can't control goroutine lifetime) | |
| select { | |
| case <-res: | |
| return true | |
| case <-ctx.Done(): | |
| return false | |
| } | |
| } | |
| ///////////////////////// | |
| // Resources usage utils | |
| ///////////////////////// | |
| func bToMb(b uint64) uint64 { | |
| return b / 1024 / 1024 | |
| } | |
| func PrintMemUsage() { | |
| var m runtime.MemStats | |
| runtime.ReadMemStats(&m) | |
| // For info on each, see: https://golang.org/pkg/runtime/#MemStats | |
| log.Printf("Alloc = %v MiB", bToMb(m.Alloc)) | |
| log.Printf("TotalAlloc = %v MiB", bToMb(m.TotalAlloc)) | |
| log.Printf("Sys = %v MiB", bToMb(m.Sys)) | |
| log.Printf("NumGoroutine = %v", runtime.NumGoroutine()) | |
| log.Print("") | |
| } |
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