[GitHub] [activemq-artemis] franz1981 edited a comment on pull request #3392: ARTEMIS-3045 ReplicationManager can batch sent replicated packets

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franz1981 edited a comment on pull request #3392:
URL: https://github.com/apache/activemq-artemis/pull/3392#issuecomment-769689978


   @michaelandrepearce There is any chance that this PR could be tried on a real hardware? 
   I'm having some problem to get it ATM.
   
   That should improve replication performance (especially with small sized messages ie < MTU size):  this PR try to batch records appends on the live broker before sending it to the backup broker, maximizing the usage of the outbound buffer provided by Netty.
   That should help submitting the send requests saving potential signaling to wake-up the event loop on each submitted packet.
   In turn, this could help to better use the network bandwidth, saving from sending near empty TCP packets.
   
   Despite batching seems to trade-off latency vs troughput perf, here it shouldn't happen, because:
   - we send a batch of packets from the same thread, improving cache misses while reading the batch of packets
   - reducing the amount of syscalls per packet means amortizing the latency cost per-packet, given that syscalls live vecored writes tends to have near fixed costs
   
   My only concern is that impl-wise it could be implemented much better, as mentioned on https://github.com/apache/activemq-artemis/pull/3392#issuecomment-757663864 and that batching could have some upper limit in the amount of bytes other then Netty buffering that could be maybe too big.
   


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