scion/ping: wait for send go routine to terminate #4392
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Wait for the ping sender go routine to terminate before we return the stats. With bad luck, the receiver go routine receives all the replies before the sender go routine has terminated. Because only the sender go routine increments the stats.Sent count, we end up with wrong stats that claim more packets were received then sent.
matzf
approved these changes
Sep 18, 2023
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Just to slightly expand on the description of the problem (because I had initially misunderstood this to be about spurious echo packets); the race condition is that WriteTo in the last pinger.send succeeds, but then the writer go-routine is not scheduled to increment the stats.Sent counter before these stats are returned from pinger.Ping. This only seems likely to happen with very low latency (e.g. ping localhost).
Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status:complete! all files reviewed, all discussions resolved (waiting on @oncilla)
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Wait for the ping sender go routine to terminate before we return the stats. With bad luck, the receiver go routine receives all the replies before the sender go routine has terminated. Because only the sender go routine increments the stats.Sent count at the end, we can end up with wrong stats that claim more packets were received then sent.
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