Glen Geng created HDDS-4228:
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Summary: ALLOCATE_BLOCK of scm audit log miss num
Key: HDDS-4228
URL: https://issues.apache.org/jira/browse/HDDS-4228
Project: Hadoop Distributed Data Store
Issue Type: Improvement
Reporter: Glen Geng
Assignee: Marton Elek
Teragen reported to be slow with low number of mappers compared to HDFS.
In my test (one pipeline, 3 yarn nodes) 10 g teragen with HDFS was ~3 mins but
with Ozone it was 6 mins. It could be fixed with using more mappers, but when I
investigated the execution I found a few problems reagrding to the BufferPool
management.
1. IncrementalChunkBuffer is slow and it might not be required as BufferPool
itself is incremental
2. For each write operation the bufferPool.allocateBufferIfNeeded is called
which can be a slow operation (positions should be calculated).
3. There is no explicit support for write(byte) operations
In the flamegraph it's clearly visible that with low number of mappers the
client is busy with buffer operations. After the patch the rpc call and the
checksum calculation give the majority of the time.
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