[ https://issues.apache.org/jira/browse/HADOOP-14535?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Mingliang Liu updated HADOOP-14535: ----------------------------------- Fix Version/s: (was: 3.0.0-alpha4) (was: 2.9.0) > Support for random access and seek of block blobs > ------------------------------------------------- > > Key: HADOOP-14535 > URL: https://issues.apache.org/jira/browse/HADOOP-14535 > Project: Hadoop Common > Issue Type: Improvement > Components: fs/azure > Reporter: Thomas > Assignee: Thomas > Attachments: > 0001-Random-access-and-seek-imporvements-to-azure-file-system.patch > > > This change adds a seek-able stream for reading block blobs to the wasb:// > file system. > If seek() is not used or if only forward seek() is used, the behavior of > read() is unchanged. > That is, the stream is optimized for sequential reads by reading chunks (over > the network) in > the size specified by "fs.azure.read.request.size" (default is 4 megabytes). > If reverse seek() is used, the behavior of read() changes in favor of reading > the actual number > of bytes requested in the call to read(), with some constraints. If the size > requested is smaller > than 16 kilobytes and cannot be satisfied by the internal buffer, the network > read will be 16 > kilobytes. If the size requested is greater than 4 megabytes, it will be > satisfied by sequential > 4 megabyte reads over the network. > This change improves the performance of FSInputStream.seek() by not closing > and re-opening the > stream, which for block blobs also involves a network operation to read the > blob metadata. Now > NativeAzureFsInputStream.seek() checks if the stream is seek-able and moves > the read position. > [^attachment-name.zip] -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org