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From Micael Capitão (JIRA) <j...@apache.org>
Subject [jira] [Created] (TEPHRA-232) Transaction metadata sent on each put is too big
Date Tue, 06 Jun 2017 10:00:23 GMT
Micael Capitão created TEPHRA-232:

             Summary: Transaction metadata sent on each put is too big
                 Key: TEPHRA-232
                 URL: https://issues.apache.org/jira/browse/TEPHRA-232
             Project: Tephra
          Issue Type: Bug
         Environment: HBase 1.2.0-cdh5.11
CentOS 7.3
4x machines
Bandwidth between machines 1Gbps
            Reporter: Micael Capitão
            Assignee: Poorna Chandra
            Priority: Critical

I've been testing Tephra 0.11.0 (and more recently 0.12.0) for a project that may need transactions
on top of HBase and I find it's performance, for instance, for a bulk load, very poor. Let's
not discuss why am I doing a bulk load with transactions.

In my use case I am generating batches of ~10000 elements and inserting them with the *put(List<Put>
puts)* method. There is no concurrent writers or readers.
If I do the put without transactions it takes ~0.5s. If I use the *TransactionAwareHTable*
it takes ~12s.
In both cases the network bandwidth is fully utilised.

I've tracked down the performance killer to be the *addToOperation(OperationWithAttributes
op, Transaction tx)* on the TransactionAwareHTable.

I've created a TransactionAwareHTableFix with the *addToOperation(txPut, tx)* commented, and
used it in my code, and each batch started to take ~0.5s.

Then I checked what was being done inside the *addToOperation* method and verified that the
issue has something to do with the serialization of the Transaction object. The serialized
Transaction object has 104171 bytes of length. Considering that it happens for each put, basically
my batch of ~10000 elements has ~970MB of serialized transactions, which explains the 12s
vs 5s to be processed at the same time that the network is exhausted.

It seems that the transactions' metadata, despite being sent to HBase, is not stored so the
final table size, with or without transactions, is the same.

Is this metadata encoding and send behaviour expected? This is making Tephra unusable, at
least with only 1Gbps bandwidth.

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