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https://issues.apache.org/jira/browse/HDFS-14355?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16805884#comment-16805884
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Anoop Sam John commented on HDFS-14355:
---------------------------------------
getBlockInputStreamWithCheckingPmemCache -> Can be private method
public PmemVolumeManager getPmemVolumeManager -> Why being exposed? For tests?
If so can this be package private? And also mark it with @VisibleForTesting
I think the afterCache() thing is an unwanted indirection
{code}
FsDatasetCache
try {
411 mappableBlock = cacheLoader.load(length, blockIn, metaIn,
412 blockFileName, key);
413 } catch (ChecksumException e) {
414 // Exception message is bogus since this wasn't caused by
a file read
418 LOG.warn("Failed to cache the block [key=" + key + "]!",
e);
419 return;
420 }
421 mappableBlock.afterCache();
PmemMappedBlock
@Override
58 public void afterCache() {
59 pmemVolumeManager.afterCache(key, volumeIndex);
60 }
PmemVolumeManager
public void afterCache(ExtendedBlockId key, Byte volumeIndex) {
299 blockKeyToVolume.put(key, volumeIndex);
300 }
{code}
Actually in PmemMappableBlockLoader#load, once the load is successful
(mappableBlock != null), we can do this pmemVolumeManager work right?
{code}
public void close() {
64 pmemVolumeManager.afterUncache(key);
...
68 FsDatasetUtil.deleteMappedFile(cacheFilePath);
{code}
Call afterUncache() after delete the file
public PmemVolumeManager(DNConf dnConf)
Can we only pass pmemVolumes and maxLockedPmem? That is cleaner IMO
getVolumeByIndex -> can this be package private
getCacheFilePath(ExtendedBlockId key) -> Better name would be
getCachedPath(ExtendedBlockId)
dfs.datanode.cache.pmem.capacity -> Am not sure any naming convention u follow
in HDFS. But as a user I would prefer a name dfs.datanode.pmem.cache.capacity.
Ditto for dfs.datanode.cache.pmem.dirs
> Implement HDFS cache on SCM by using pure java mapped byte buffer
> -----------------------------------------------------------------
>
> Key: HDFS-14355
> URL: https://issues.apache.org/jira/browse/HDFS-14355
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: caching, datanode
> Reporter: Feilong He
> Assignee: Feilong He
> Priority: Major
> Attachments: HDFS-14355.000.patch, HDFS-14355.001.patch,
> HDFS-14355.002.patch, HDFS-14355.003.patch, HDFS-14355.004.patch,
> HDFS-14355.005.patch, HDFS-14355.006.patch, HDFS-14355.007.patch,
> HDFS-14355.008.patch
>
>
> This task is to implement the caching to persistent memory using pure
> {{java.nio.MappedByteBuffer}}, which could be useful in case native support
> isn't available or convenient in some environments or platforms.
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