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https://issues.apache.org/jira/browse/CASSANDRA-8630?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14733187#comment-14733187
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Stefania commented on CASSANDRA-8630:
-------------------------------------
The following Coverity defects were reported after committing this, working on
a fix:
{code}
*** CID 1322973: FindBugs: Correctness
(FB.UR_UNINIT_READ_CALLED_FROM_SUPER_CONSTRUCTOR)
/src/java/org/apache/cassandra/io/util/RandomAccessReader.java: 83 in
org.apache.cassandra.io.compress.CompressedRandomAccessReader.initializeBuffer()()
77 this.bufferType = builder.bufferType;
78
79 if (builder.bufferSize <= 0)
80 throw new IllegalArgumentException("bufferSize must be
positive");
81
82 if (builder.initializeBuffers)
>>> CID 1322973: FindBugs: Correctness
>>> (FB.UR_UNINIT_READ_CALLED_FROM_SUPER_CONSTRUCTOR)
>>> Call from superclass constructor here
83 initializeBuffer();
84 }
85
86 protected int getBufferSize(Builder builder)
87 {
88 if (builder.limiter == null)
** CID 1322970: FindBugs: Dodgy code (FB.NS_DANGEROUS_NON_SHORT_CIRCUIT)
/src/java/org/apache/cassandra/hints/ChecksummedDataInput.java: 140 in
org.apache.cassandra.hints.ChecksummedDataInput.updateCrc()()
________________________________________________________________________________________________________
*** CID 1322970: FindBugs: Dodgy code (FB.NS_DANGEROUS_NON_SHORT_CIRCUIT)
/src/java/org/apache/cassandra/hints/ChecksummedDataInput.java: 140 in
org.apache.cassandra.hints.ChecksummedDataInput.updateCrc()()
134 super.reBuffer();
135 crcPosition = buffer.position();
136 }
137
138 private void updateCrc()
139 {
>>> CID 1322970: FindBugs: Dodgy code (FB.NS_DANGEROUS_NON_SHORT_CIRCUIT)
>>> Potentially dangerous use of non-short-circuit logic.
140 if (crcPosition == buffer.position() | crcUpdateDisabled)
141 return;
142
143 assert crcPosition >= 0 && crcPosition < buffer.position();
144
145 ByteBuffer unprocessed = buffer.duplicate();
** CID 1322957: (FORWARD_NULL)
{code}
> Faster sequential IO (on compaction, streaming, etc)
> ----------------------------------------------------
>
> Key: CASSANDRA-8630
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8630
> Project: Cassandra
> Issue Type: Improvement
> Components: Core, Tools
> Reporter: Oleg Anastasyev
> Assignee: Stefania
> Labels: compaction, performance
> Fix For: 3.x
>
> Attachments: 8630-FasterSequencialReadsAndWrites.txt, cpu_load.png,
> flight_recorder_001_files.tar.gz, flight_recorder_002_files.tar.gz,
> mmaped_uncomp_hotspot.png
>
>
> When node is doing a lot of sequencial IO (streaming, compacting, etc) a lot
> of CPU is lost in calls to RAF's int read() and DataOutputStream's write(int).
> This is because default implementations of readShort,readLong, etc as well as
> their matching write* are implemented with numerous calls of byte by byte
> read and write.
> This makes a lot of syscalls as well.
> A quick microbench shows than just reimplementation of these methods in
> either way gives 8x speed increase.
> A patch attached implements RandomAccessReader.read<Type> and
> SequencialWriter.write<Type> methods in more efficient way.
> I also eliminated some extra byte copies in CompositeType.split and
> ColumnNameHelper.maxComponents, which were on my profiler's hotspot method
> list during tests.
> A stress tests on my laptop show that this patch makes compaction 25-30%
> faster on uncompressed sstables and 15% faster for compressed ones.
> A deployment to production shows much less CPU load for compaction.
> (I attached a cpu load graph from one of our production, orange is niced CPU
> load - i.e. compaction; yellow is user - i.e. not compaction related tasks)
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