Don't hold entire MQTT retained messages in memory #4228
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kozlovic
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Jun 9, 2023
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Could change signature of one function since we don't seem to need the old sequence anymore. But more importantly, I wonder if the mqttCheckPubRetainedPerms() function should not be refactored a little bit knowing that we now have to read messages (possibly from disk, and possibly a lot of them).
Signed-off-by: Neil Twigg <neil@nats.io>
Signed-off-by: Neil Twigg <neil@nats.io>
Signed-off-by: Neil Twigg <neil@nats.io>
…'t hold locks longer than needed Signed-off-by: Neil Twigg <neil@nats.io>
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kozlovic
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Jun 13, 2023
kozlovic
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Jun 13, 2023
server/mqtt.go
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| // Get all of the retained messages. Then we will sort them so | ||
| // that they are in sequence order, which should help the file | ||
| // store to not have to load out-of-order blocks so often. | ||
| asm.mu.Lock() |
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You could use RLock()/RUnlock() here since mqttAccountSessionManager.mu is a sync.RWMutex and you are just reading from asm.retmsgs.
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Good call. Thanks for your reviews on this!
Signed-off-by: Neil Twigg <neil@nats.io>
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This PR separates out the small amount of necessary metadata for retained messages (stream sequence, floor) from the message itself, instead accessing the messages themselves with KV-like access patterns.
This should save quite a bit of memory where there are lots of retained messages since we only now need to hold a small amount of metadata instead of the entire messages.
Signed-off-by: Neil Twigg neil@nats.io