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https://issues.apache.org/jira/browse/HADOOP-1702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Raghu Angadi updated HADOOP-1702:
---------------------------------
Fix Version/s: 0.17.0
Description:
HADOOP-1649 adds extra buffering to improve write performance. The following
diagram shows buffers as pointed by (numbers). Each eatra buffer adds an extra
copy since most of our read()/write()s match the io.bytes.per.checksum, which
is much smaller than buffer size.
{noformat}
(1) (2) (3) (5)
+---||----[ CLIENT ]---||----<>-----||---[ DATANODE ]---||--<>-> to Mirror
| (buffer) (socket) | (4)
| +--||--+
===== |
===== =====
(disk) =====
{noformat}
Currently loops that read and write block data, handle one checksum chunk at a
time. By reading multiple chunks at a time, we can remove buffers (1), (2),
(3), and (5).
Similarly some copies can be reduced when clients read data from the DFS.
was:
HADOOP-1649 adds extra buffering to improve write performance. The following
diagram shows buffers as pointed by (numbers). Each eatra buffer adds an extra
copy since most of our read()/write()s match the io.bytes.per.checksum, which
is much smaller than buffer size.
{noformat}
(1) (2) (3) (5)
+---||----[ CLIENT ]---||----<>-----||---[ DATANODE ]---||--<>-> to Mirror
| (buffer) (socket) | (4)
| +--||--+
===== |
===== =====
(disk) =====
{noformat}
Currently loops that read and write block data, handle one checksum chunk at a
time. By reading multiple chunks at a time, we can remove buffers (1), (2),
(3), and (5).
Similarly some copies can be reduced when clients read data from the DFS.
> Reduce buffer copies when data is written to DFS
> ------------------------------------------------
>
> Key: HADOOP-1702
> URL: https://issues.apache.org/jira/browse/HADOOP-1702
> Project: Hadoop Core
> Issue Type: Bug
> Components: dfs
> Affects Versions: 0.14.0
> Reporter: Raghu Angadi
> Assignee: Raghu Angadi
> Fix For: 0.17.0
>
>
> HADOOP-1649 adds extra buffering to improve write performance. The following
> diagram shows buffers as pointed by (numbers). Each eatra buffer adds an
> extra copy since most of our read()/write()s match the io.bytes.per.checksum,
> which is much smaller than buffer size.
> {noformat}
> (1) (2) (3) (5)
> +---||----[ CLIENT ]---||----<>-----||---[ DATANODE ]---||--<>-> to Mirror
>
> | (buffer) (socket) | (4)
> | +--||--+
> ===== |
> ===== =====
> (disk) =====
> {noformat}
> Currently loops that read and write block data, handle one checksum chunk at
> a time. By reading multiple chunks at a time, we can remove buffers (1), (2),
> (3), and (5).
> Similarly some copies can be reduced when clients read data from the DFS.
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