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https://issues.apache.org/jira/browse/HBASE-17623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15891720#comment-15891720
]
ramkrishna.s.vasudevan commented on HBASE-17623:
------------------------------------------------
I verified the patch. Looks great.
bq.* @param data encoded bytes with header
Is this the encoded bytes or the bytes with header that has to be encoded?
Not your patch,
{code}
if (blockType == BlockType.DATA) {
this.dataBlockEncoder.endBlockEncoding(dataBlockEncodingCtx,
userDataStream,
baosInMemory.getBuffer(), blockType);
blockType = dataBlockEncodingCtx.getBlockType();
}
{code}
Internally we write the int
{code}
Bytes.putInt(uncompressedBytesWithHeader,
HConstants.HFILEBLOCK_HEADER_SIZE + DataBlockEncoding.ID_SIZE,
state.unencodedDataSizeWritten
);
{code}
So are we sure that the baosInMemory has the place to write this int?
> Reuse the bytes array when building the hfile block
> ---------------------------------------------------
>
> Key: HBASE-17623
> URL: https://issues.apache.org/jira/browse/HBASE-17623
> Project: HBase
> Issue Type: Improvement
> Reporter: CHIA-PING TSAI
> Assignee: CHIA-PING TSAI
> Priority: Minor
> Fix For: 2.0.0, 1.4.0
>
> Attachments: after(snappy_hfilesize=5.04GB).png,
> after(snappy_hfilesize=755MB).png, before(snappy_hfilesize=5.04GB).png,
> before(snappy_hfilesize=755MB).png, HBASE-17623.branch-1.v0.patch,
> HBASE-17623.branch-1.v1.patch, HBASE-17623.v0.patch, HBASE-17623.v1.patch,
> HBASE-17623.v1.patch, HBASE-17623.v2.patch, memory allocation measurement.xlsx
>
>
> There are two improvements.
> # The onDiskBlockBytesWithHeader should maintain a bytes array which can be
> reused when building the hfile.
> # The onDiskBlockBytesWithHeader is copied to an new bytes array only when we
> need to cache the block.
> # If no block need to be cached, the uncompressedBlockBytesWithHeader will
> never be created.
> {code:title=HFileBlock.java|borderStyle=solid}
> private void finishBlock() throws IOException {
> if (blockType == BlockType.DATA) {
> this.dataBlockEncoder.endBlockEncoding(dataBlockEncodingCtx,
> userDataStream,
> baosInMemory.getBuffer(), blockType);
> blockType = dataBlockEncodingCtx.getBlockType();
> }
> userDataStream.flush();
> // This does an array copy, so it is safe to cache this byte array when
> cache-on-write.
> // Header is still the empty, 'dummy' header that is yet to be filled
> out.
> uncompressedBlockBytesWithHeader = baosInMemory.toByteArray();
> prevOffset = prevOffsetByType[blockType.getId()];
> // We need to set state before we can package the block up for
> cache-on-write. In a way, the
> // block is ready, but not yet encoded or compressed.
> state = State.BLOCK_READY;
> if (blockType == BlockType.DATA || blockType == BlockType.ENCODED_DATA)
> {
> onDiskBlockBytesWithHeader = dataBlockEncodingCtx.
> compressAndEncrypt(uncompressedBlockBytesWithHeader);
> } else {
> onDiskBlockBytesWithHeader = defaultBlockEncodingCtx.
> compressAndEncrypt(uncompressedBlockBytesWithHeader);
> }
> // Calculate how many bytes we need for checksum on the tail of the
> block.
> int numBytes = (int) ChecksumUtil.numBytes(
> onDiskBlockBytesWithHeader.length,
> fileContext.getBytesPerChecksum());
> // Put the header for the on disk bytes; header currently is
> unfilled-out
> putHeader(onDiskBlockBytesWithHeader, 0,
> onDiskBlockBytesWithHeader.length + numBytes,
> uncompressedBlockBytesWithHeader.length,
> onDiskBlockBytesWithHeader.length);
> // Set the header for the uncompressed bytes (for cache-on-write) --
> IFF different from
> // onDiskBlockBytesWithHeader array.
> if (onDiskBlockBytesWithHeader != uncompressedBlockBytesWithHeader) {
> putHeader(uncompressedBlockBytesWithHeader, 0,
> onDiskBlockBytesWithHeader.length + numBytes,
> uncompressedBlockBytesWithHeader.length,
> onDiskBlockBytesWithHeader.length);
> }
> if (onDiskChecksum.length != numBytes) {
> onDiskChecksum = new byte[numBytes];
> }
> ChecksumUtil.generateChecksums(
> onDiskBlockBytesWithHeader, 0, onDiskBlockBytesWithHeader.length,
> onDiskChecksum, 0, fileContext.getChecksumType(),
> fileContext.getBytesPerChecksum());
> }{code}
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