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https://issues.apache.org/jira/browse/TEZ-3732?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16013579#comment-16013579
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Gopal V commented on TEZ-3732:
------------------------------
Before:
{code}
org.apache.tez.runtime.library.common.InputAttemptIdentifier object internals:
OFFSET SIZE
TYPE DESCRIPTION VALUE
0 4
(object header) 01 00 00 00 (00000001
00000000 00000000 00000000) (1)
4 4
(object header) 00 00 00 00 (00000000
00000000 00000000 00000000) (0)
8 4
(object header) 18 8e 08 00 (00011000
10001110 00001000 00000000) (560664)
12 4
int InputAttemptIdentifier.inputIdentifier 0
16 4
int InputAttemptIdentifier.attemptNumber 0
20 4
int InputAttemptIdentifier.spillEventId -1
24 1
boolean InputAttemptIdentifier.shared false
25 3
(alignment/padding gap)
28 4
java.lang.String InputAttemptIdentifier.pathComponent null
32 4
org.apache.tez.runtime.library.common.InputAttemptIdentifier.SPILL_INFO
InputAttemptIdentifier.fetchTypeInfo (object)
36 4
(loss due to the next object alignment)
Instance size: 40 bytes
Space losses: 3 bytes internal + 4 bytes external = 7 bytes total
{code}
{code}
org.apache.tez.runtime.library.common.shuffle.orderedgrouped.MapOutput object
internals:
OFFSET SIZE
TYPE DESCRIPTION VALUE
0 4
(object header) 01 00 00 00 (00000001
00000000 00000000 00000000) (1)
4 4
(object header) 00 00 00 00 (00000000
00000000 00000000 00000000) (0)
8 4
(object header) 18 8e 08 00 (00011000
10001110 00001000 00000000) (560664)
12 4
int MapOutput.id 1
16 8
long MapOutput.size 0
24 1
boolean MapOutput.primaryMapOutput false
25 3
(alignment/padding gap)
28 4
org.apache.tez.runtime.library.common.shuffle.orderedgrouped.MapOutput.Type
MapOutput.type null
32 4
org.apache.tez.runtime.library.common.InputAttemptIdentifier
MapOutput.attemptIdentifier null
36 4
org.apache.tez.runtime.library.common.shuffle.orderedgrouped.MergeManager
MapOutput.merger null
40 4
byte[] MapOutput.memory null
44 4
org.apache.hadoop.io.BoundedByteArrayOutputStream MapOutput.byteStream
null
48 4
org.apache.hadoop.fs.FileSystem MapOutput.localFS null
52 4
org.apache.hadoop.fs.Path MapOutput.tmpOutputPath null
56 4
org.apache.hadoop.io.FileChunk MapOutput.outputPath null
60 4
java.io.OutputStream MapOutput.disk null
Instance size: 64 bytes
Space losses: 3 bytes internal + 0 bytes external = 3 bytes total
{code}
> Reduce Object size of InputAttemptIdentifier and MapOutput for large jobs
> -------------------------------------------------------------------------
>
> Key: TEZ-3732
> URL: https://issues.apache.org/jira/browse/TEZ-3732
> Project: Apache Tez
> Issue Type: Bug
> Reporter: Jonathan Eagles
> Assignee: Jonathan Eagles
> Attachments: TEZ-3732.1.patch
>
>
> Objects in 64bit java are 12bytes + member size aligned to 8 bytes
> InputAttemptIdentifier -> 33Bytes gets aligned up to 40 bytes
> This class is just one byte over the 32 byte alignment. Reducing object size
> by one byte can save 8 bytes per object.
> This is ~8MB savings for 1,000,000 inputs and ~80 MB savings for tasks with
> 10,000,000 inputs to fetch (Yes this is a real job)
> MapOutput -> 45 bytes gets aligned to 48 bytes
> This class can be sub-classed to avoid all sub-classes paying the object size
> cost for the other sub-classes
> Wait InMemory and DiskDirect -> 32 bytes
> Disk -> 40 bytes
> Total savings is harder to account for but more than the above case.
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