Hi,
On Linux, if I compile and run this simple program:
package main
import (
"fmt"
"net/http"
"time"
)
type x struct{}
func (x) ServeHTTP(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("aaaa"))
}
func main() {
sp := &http.Server{
ReadHeaderTimeout: 5 * time.Second,
ReadTimeout: 5 * time.Second,
WriteTimeout: 5 * time.Second,
IdleTimeout: 30 * time.Second,
Addr: ":8080",
Handler: x{},
}
fmt.Println(sp.ListenAndServe())
}
After a while I start to see constant CPU activity (1% to 7%) even when the
server is idle.
If I run "sudo strace -f -c -p <pid>" I get constant very fast calls like:
[pid 131277] 23:42:16 nanosleep({tv_sec=0, tv_nsec=10000000}, NULL) = 0
[pid 131277] 23:42:16 nanosleep({tv_sec=0, tv_nsec=10000000}, NULL) = 0
[pid 131277] 23:42:16 nanosleep({tv_sec=0, tv_nsec=10000000}, NULL) = 0
[pid 131277] 23:42:16 nanosleep({tv_sec=0, tv_nsec=10000000}, NULL) = 0
[pid 131277] 23:42:16 nanosleep({tv_sec=0, tv_nsec=10000000}, NULL) = 0
....
It never stops. Sometimes the CPU goes to 100% for a while and then go back
down to 1%.. This happens only in one or two cores.
This doesn't happen with Go 1.16. I have been checking all versions and it
starts in Go 1.17
If I run the program with go run instead of compiling and running the
binary, I can't reproduce it.
Sometimes it starts after a couple of http calls and sometimes I do a few
"wrk -d2 http://localhost:8080"; calls to trigger it (wrk is a web stress
tool). But as soon as it starts making the nanosleep calls, it doesn't
stop, no matter how long the server is iddle.
If I remove the timeout values or set them to a short period, like one
second for example, I am also not able to reproduce it. But with longer
values it happens very quickly. I am surprised of not seing it reported.
Do you know what can be going on?
Thank you!
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