Hi Abhi.
I believe that your logic is faulty. The timeout does take place – but it
doesn’t really do what you wanted, I think.
GetWorkerValues isn’t going to send it’s info because the “range cs” can’t
finish until the channel is closed. The channel is not closed until both
workers are finished – timeout or not, thus it always contains the info for
both workers.
John
John Souvestre - New Orleans LA
From: [email protected] [mailto:[email protected]] On
Behalf Of [email protected]
Sent: 2017 January 08, Sun 06:24
To: golang-nuts
Subject: Re: [go-nuts] Multiple goroutine timeout for waitgroup not working
hi John
I am expecting work2 should not include in
headers = <-messgesResponse
so output of below should be Len = 1 and should print only work 1 only and not
2 ( as work 2 is timed out )
fmt.Printf("len > %s\n", len(headers))
for i:=0;i<len(headers);i++ {
fmt.Printf("Name > %s\n", headers[i].Name)
}
basically workgroup timeout doesnt close the timeout works
select {
case <-time.After(2 * time.Second): //This works but
dont stop the work2
return
}
Do I need to explicitly close them in
select {
case <-time.After(2 * time.Second):
close(cs)
return
}
Thanks for the help
Rgds,
Abhi
On Sunday, January 8, 2017 at 5:40:01 PM UTC+5:30, John Souvestre wrote:
Hi Abhi.
I believe that the wait group timeout (in monitorWorker) was set to 2 seconds
in the code you posted.
I put a debugging print in the timeout case, and it is taking place.
What were you expecting to see?
John
John Souvestre - New Orleans LA
From: [email protected] <javascript:>
[mailto:[email protected] <javascript:> ] On Behalf Of
[email protected] <javascript:>
Sent: 2017 January 08, Sun 05:48
To: golang-nuts
Subject: Re: [go-nuts] Multiple goroutine timeout for waitgroup not working
hi John
Thanks for the reply
sorry
I mean Work2 takes => 3 seconds
work1 takes => 1 seconds
Wait group timeout is => 1 seconds
It is expected that only Work1 should get done and Work 2 should get timeout
which is not happening
Waitgroup waits for both work.. program doing something wrong
func Work2(message chan *TestStruct, wg *sync.WaitGroup, tokenNumber string) {
defer wg.Done()
v1 := new(TestStruct)
v1.Name = tokenNumber
time.Sleep(3 * time.Second)
message <- v1
fmt.Printf("finished %s\n", tokenNumber)
}
Thanks,
Abhi
On Sunday, January 8, 2017 at 5:09:56 PM UTC+5:30, John Souvestre wrote:
What do you see when you run it? I see:
finished 1
finished 2
len > %!s(int=2) ç Using a string format for an int
Name > 1
Name > 2
Ø Work 2 - have 3 second
I’m not sure exactly what you are trying to do, but I suspect that changing
“messges” to hold 2 items might make it work.
messges := make(chan *TestStruct, 2)
I’m guessing, but I suspect that you didn’t realize that if Work1 runs first,
then Work2 will block since the channel is full (or until you close it).
John
John Souvestre - New Orleans LA
From: [email protected] [mailto:[email protected]] On Behalf Of
[email protected]
Sent: 2017 January 08, Sun 01:23
To: golang-nuts
Subject: [go-nuts] Multiple goroutine timeout for waitgroup not working
Can you please help to correct below program where timeout not seems working
Work 1 - have 1 second
Work 2 - have 3 second
Total Timeout - 2 sec
program wait for entire 3 seconds and return both values rather than value from
Work 1
Program >
package main
import (
"fmt"
"time"
"sync"
)
type TestStruct struct {
Name string
}
func main() {
wg := &sync.WaitGroup{}
messges := make(chan *TestStruct, 1)
wg.Add(1)
go Work1(messges, wg, "1")
wg.Add(1)
go Work2(messges, wg, "2")
monitorWorker(wg, messges)
messgesResponse := make(chan []*TestStruct)
go GetWorkerValues(messges, messgesResponse)
headers := make([]*TestStruct, 0)
headers = <-messgesResponse
fmt.Printf("len > %s\n", len(headers))
for i:=0;i<len(headers);i++ {
fmt.Printf("Name > %s\n", headers[i].Name)
}
}
func monitorWorker(wg *sync.WaitGroup, cs chan *TestStruct) {
go func() {
defer close(cs)
wg.Wait()
}()
select {
case <-time.After(2 * time.Second):
return
}
}
func Work1(message chan *TestStruct, wg *sync.WaitGroup, tokenNumber string) {
defer wg.Done()
v1 := new(TestStruct)
v1.Name = tokenNumber
time.Sleep(1 * time.Second)
message <- v1
fmt.Printf("finished %s\n", tokenNumber)
}
func Work2(message chan *TestStruct, wg *sync.WaitGroup, tokenNumber string) {
defer wg.Done()
v1 := new(TestStruct)
v1.Name = tokenNumber
time.Sleep(1 * time.Second)
message <- v1
fmt.Printf("finished %s\n", tokenNumber)
}
func GetWorkerValues(cs <-chan *TestStruct, response chan<- []*TestStruct) {
var val []*TestStruct
for header := range cs {
val = append(val, header)
}
response <- val
}
Thanks,
Abhi
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