[HDFS-9879] Erasure Coding : schedule striped blocks to be cached on DataNodes

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: caching, erasure-coding
• Assignee: Rakesh Radhakrishnan
• Reporter: Rakesh Radhakrishnan
• Created: 01/Mar/16 05:58
• Updated: 19/Jan/17 08:21

Description

This jira to discuss and implement the caching of striped block objects on the appropriate datanode.

Presently it is checking block group size and scheduling the blockGroupId to the datanode, which needs to be refined by checking the StripedBlockUtil.getInternalBlockLength() and schedule proper blockId to the datanode.

CacheReplicationMonitor.java

      if (pendingCapacity < blockInfo.getNumBytes()) {
        LOG.trace("Block {}: DataNode {} is not a valid possibility " +
            "because the block has size {}, but the DataNode only has {} " +
            "bytes of cache remaining ({} pending bytes, {} already cached.)",
            blockInfo.getBlockId(), datanode.getDatanodeUuid(),
            blockInfo.getNumBytes(), pendingCapacity, pendingBytes,
            datanode.getCacheRemaining());
        outOfCapacity++;
        continue;
      }

    for (DatanodeDescriptor datanode : chosen) {
      LOG.trace("Block {}: added to PENDING_CACHED on DataNode {}",
          blockInfo.getBlockId(), datanode.getDatanodeUuid());
      pendingCached.add(datanode);
      boolean added = datanode.getPendingCached().add(cachedBlock);
      assert added;
    }