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https://issues.apache.org/jira/browse/HDFS-17510?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Zhikai Hu updated HDFS-17510:
-----------------------------
Description:
In one of my projects, I need to dynamically adjust compression level for
different files.
However, I found that in most cases the new compression level does not take
effect as expected, the old compression level continues to be used.
Here is the relevant code snippet:
ZStandardCodec zStandardCodec = new ZStandardCodec();
zStandardCodec.setConf(conf);
conf.set("io.compression.codec.zstd.level", "5"); // level may change
dynamically
conf.set("io.compression.codec.zstd", zStandardCodec.getClass().getName());
writer = SequenceFile.createWriter(conf,
SequenceFile.Writer.file(sequenceFilePath),
SequenceFile.Writer.keyClass(LongWritable.class),
SequenceFile.Writer.valueClass(BytesWritable.class),
SequenceFile.Writer.compression(CompressionType.BLOCK));
The reason is SequenceFile.Writer.init() method will call
CodecPool.getCompressor(codec, null) to get a compressor.
If the compressor is a reused instance, the conf is not applied because it is
passed as null:
public static Compressor getCompressor(CompressionCodec codec, Configuration
conf) {
Compressor compressor = borrow(compressorPool, codec.getCompressorType());
if (compressor == null)
{ compressor = codec.createCompressor(); LOG.info("Got brand-new
compressor ["+codec.getDefaultExtension()+"]"); }
else {
compressor.reinit(conf); // conf is null here
if(LOG.isDebugEnabled())
{ LOG.debug("Got recycled compressor"); }
}
Please also refer to my unit test to reproduce the bug.
To address this bug, I modified the code to ensure that the configuration is
read back from the codec when a compressor is reused.
was:
In one of my projects, I need to dynamically adjust compression level for
different files.
However, I found that in most cases the new compression level does not take
effect as expected, the old compression level continues to be used.
Here is the relevant code snippet:
ZStandardCodec zStandardCodec = new ZStandardCodec();
zStandardCodec.setConf(conf);
conf.set("io.compression.codec.zstd.level", "5"); // level may change
dynamically
conf.set("io.compression.codec.zstd", zStandardCodec.getClass().getName());
writer = SequenceFile.createWriter(conf,
SequenceFile.Writer.file(sequenceFilePath),
SequenceFile.Writer.keyClass(LongWritable.class),
SequenceFile.Writer.valueClass(BytesWritable.class),
SequenceFile.Writer.compression(CompressionType.BLOCK));
The reason is SequenceFile.Writer.init() method will call
CodecPool.getCompressor(codec, null) to get a compressor.
If the compressor is a reused instance, the conf is not applied because it is
passed as null:
public static Compressor getCompressor(CompressionCodec codec, Configuration
conf) {
Compressor compressor = borrow(compressorPool, codec.getCompressorType());
if (compressor == null) {
compressor = codec.createCompressor();
LOG.info("Got brand-new compressor ["+codec.getDefaultExtension()+"]");
} else {
compressor.reinit(conf); // conf is null here
if(LOG.isDebugEnabled()) {
LOG.debug("Got recycled compressor");
}
}
Please also refer to my unit test to reproduce the bug.
To address this bug, I modified the code to ensure that the configuration is
read back from the codec when a compressor is reused.
> Change of Codec configuration does not work
> -------------------------------------------
>
> Key: HDFS-17510
> URL: https://issues.apache.org/jira/browse/HDFS-17510
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: compress
> Reporter: Zhikai Hu
> Priority: Minor
>
> In one of my projects, I need to dynamically adjust compression level for
> different files.
> However, I found that in most cases the new compression level does not take
> effect as expected, the old compression level continues to be used.
> Here is the relevant code snippet:
> ZStandardCodec zStandardCodec = new ZStandardCodec();
> zStandardCodec.setConf(conf);
> conf.set("io.compression.codec.zstd.level", "5"); // level may change
> dynamically
> conf.set("io.compression.codec.zstd", zStandardCodec.getClass().getName());
> writer = SequenceFile.createWriter(conf,
> SequenceFile.Writer.file(sequenceFilePath),
>
> SequenceFile.Writer.keyClass(LongWritable.class),
>
> SequenceFile.Writer.valueClass(BytesWritable.class),
>
> SequenceFile.Writer.compression(CompressionType.BLOCK));
> The reason is SequenceFile.Writer.init() method will call
> CodecPool.getCompressor(codec, null) to get a compressor.
> If the compressor is a reused instance, the conf is not applied because it is
> passed as null:
> public static Compressor getCompressor(CompressionCodec codec, Configuration
> conf) {
> Compressor compressor = borrow(compressorPool, codec.getCompressorType());
> if (compressor == null)
> { compressor = codec.createCompressor(); LOG.info("Got brand-new
> compressor ["+codec.getDefaultExtension()+"]"); }
> else {
> compressor.reinit(conf); // conf is null here
> if(LOG.isDebugEnabled())
> { LOG.debug("Got recycled compressor"); }
> }
> Please also refer to my unit test to reproduce the bug.
> To address this bug, I modified the code to ensure that the configuration is
> read back from the codec when a compressor is reused.
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