Memory leaks in govpp core #184
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Signed-off-by: Vladimir Lavor <vlavor@cisco.com>
hardeker
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Jan 15, 2024
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| replyTimeoutTimer := time.NewTimer(ch.receiveReplyTimeout) | ||
| defer replyTimeoutTimer.Stop() | ||
| select { | ||
| case ch.replyChan <- reply: | ||
| return // reply sent ok | ||
| case <-time.After(ch.receiveReplyTimeout): | ||
| // receiver still not ready | ||
| case <-replyTimeoutTimer.C: | ||
| // receiver still isn't ready |
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I understand the idea but I don't understand the issue.
time.After creates a temporary leak until the timer expires. After the expiration, it is supposed to be garbage collected. By default the timeout is 100ms. So I am not sure how you can fire enough API calls in such a little time window to create a significant memory impact.
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@hardeker hello Arthur, two reasons:
- the reply timeout is indeed 100ms by default, but is configurable via
ReplyChannelTimeoutso the garbage collection can be easily and unknowingly by a user "postponed". - It depends on what we consider a "significant memory impact". I understand the impact is temporary, but memory spikes are noticeable as the timer is responsible for >30% of total GoVPP memory consumption. Or even much more, see this example:
With the fix, the time.After() drops to ~10kB in the same scenario.
hardeker
approved these changes
Jan 16, 2024
ondrej-fabry
approved these changes
Jan 23, 2024
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Fixed memory leaks in GoVPP core stream and request handler.
Edit: the second issue was already addressed in #182
The temporary leak is occurring in the request handler.
<-time.After()is not garbage-collected before expiration and shouldn't be used in such a frequently called method.The second memory leak is permanent, caused by the timer not being closed, causing a slow increase in memory consumption over time.
Performance profile (done on ~1000 API calls using the Stream API):
With the fix:
