When we read from HDFS, we overread to pick up the next blocks header.
Doing this saves a seek as we move through the hfile; we save having to
do an explicit seek just to read the block header every time we need to
read the body. We used to read in the next header as part of the
current blocks buffer. This buffer was then what got persisted to
blockcache; so we were over-persisting: our block plus the next blocks'
header (33 bytes).
This patch undoes this over-persisting.
Removes support for version 1 blocks (0.2 was added in hbase-0.92.0).
Not needed any more.
There is an open question on whether checksums should be persisted
when caching. The code seems to say no but if cache is SSD backed or
backed by anything that does not do error correction, we'll want
checksums.
Adds loads of documentation.
M hbase-common/src/main/java/org/apache/hadoop/hbase/io/hfile/BlockType.java
(write) Add writing from a ByteBuff.
M hbase-common/src/main/java/org/apache/hadoop/hbase/nio/ByteBuff.java
(toString) Add one so ByteBuff looks like ByteBuffer when you click on
it in IDE
M hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java
Remove support for version 1 blocks.
Cleaned up handling of metadata added when we serialize a block to
caches. Metadata is smaller now.
When we serialize (used when caching), do not persist the next blocks
header if present.
Removed a bunch of methods, a few of which had overlapping
functionality and others that exposed too much of our internals.
Also removed a bunch of constructors and unified the constructors we
had left over making them share a common init method.
Shutdown access to defines that should only be used internally here.
Renamed all to do w/ 'EXTRA' and 'extraSerialization' to instead talk
about metadata saved to caches; was unclear previously what EXTRA was
about.
Renamed static final declarations as all uppercase.
(readBlockDataInternal): Redid. Couldn't make sense of it previously.
Undid heavy-duty parse of header by constructing HFileBlock. Other
cleanups. Its 1/3rd the length it used to be. More to do in here.
M hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreScanner.java
optimize Add doc on what is being optimized. Also, if a Get Scan, do not
optimize else we'll keep going after our row is DONE.
Another place to make use of the Get Scan fact is when we are DONE.. if
Get Scan, we can close out the scan.
M hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestStoreScanner.java
Add tests for Get Scans and optimize around block loading.
M hbase-common/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileContext.java
Make it emit its toString in format that matches the way we log
elsewhere
M hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java
Capitalize statics.
M hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java
Verify and cleanup documentation of hfileblock format at head of class.
Explain what 'EXTRA_SERIALIZATION_SPACE' is all about.
Connect how we serialize and deserialize... done in different places
and one way when pulling from HDFS and another when pulling from cache
(TO BE FIXED). Shut down a load of public access.
M hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderImpl.java
Add trace-level logging
M hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileScanner.java
Make it Closeable
Summary:
Use less contended things for metrics.
For histogram which was the largest culprit we use FastLongHistogram
For atomic long where possible we now use counter.
Test Plan: unit tests
Reviewers:
Subscribers:
Differential Revision: https://reviews.facebook.net/D54381
stack
Elliott Clark
tedyu
Enis Soztutar
anoopsjohn
Andrew Purtell
Matteo Bertozzi
Stephen Yuan Jiang
Jonathan M Hsieh
zhangduo
Mikhail Antonov
eshcar
ramkrishna
Misty Stanley-Jones
Gary Helmling