I see that others have already addressed the locking issued, but I noticed
something else. I don’t understand why you are using “select”. With only one
case, I think that it’s normally going to fail and exit the select block, then
loop due to the “for”. This will make it run constantly.
If you get rid of the “select” then the loop will block until something comes
in from the channel.
John
John Souvestre - New Orleans LA
From: [email protected] [mailto:[email protected]] On
Behalf Of [email protected]
Sent: 2016 October 11, Tue 21:26
To: golang-nuts
Subject: [go-nuts] infinite loop makes program stuck
Hi, there. I've read the FAQ and specifically the concurrency part. Tell me if
the problem has been discussed anywhere.
I used an infinite loop to block a goroutine until a value is big enough:
for commitIndex < index {}
I know its bad but its just a very intuitive and fast to implement. And I
incremented commitIndex in another goroutine monotonically:
for {
select {
case <-ch:
mu.Lock()
commitIndex++
mu.Unlock()
}
}
These are the only two places that access commitIndex. I didn't acquire the
lock when reading commitIndex since I think its OK to read a stale value in my
case. The program is a complex Raft replicated server so there're many other
goroutines. The problem is the program became stuck after running for a while.
commitIndex stopped updating and even the Raft servers stopped communicating
with each other. I ended up adding a Sleep() in the for loop and everything
worked. Is this normal? Or there's a problem with the goroutine scheduling?
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