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Chandni Singh commented on APEXMALHAR-2063: ------------------------------------------- I am close to completing the implementation of all the methods supported in WindowDataManager api. WindowDataManager API extended the StorageAgent API and I am thinking of deprecating the following methods which are not being used in any operator using WindowDataManager. 1. long[] getWindowIds(int operatorId) 2. long[] getWindowIds() The reason to deprecate them is that the implementation to provide just the window ids is not optimal. If all the window ids[] are expected without reading the data of those windows then we basically re-read wal files. > Integrate WAL to FS WindowDataManager > ------------------------------------- > > Key: APEXMALHAR-2063 > URL: https://issues.apache.org/jira/browse/APEXMALHAR-2063 > Project: Apache Apex Malhar > Issue Type: Improvement > Reporter: Chandni Singh > Assignee: Chandni Singh > > FS Window Data Manager is used to save meta-data that helps in replaying > tuples every completed application window after failure. For this it saves > meta-data in a file per window. Having multiple small size files on hdfs > cause issues as highlighted here: > http://blog.cloudera.com/blog/2009/02/the-small-files-problem/ > Instead FS Window Data Manager can utilize the WAL to write data and maintain > a mapping of how much data was flushed to WAL each window. > In order to use FileSystemWAL for replaying data of a finished window, there > are few changes made to FileSystemWAL this is because of following: > 1. WindowDataManager needs to reply data of every finished window. This > window may not be checkpointed. > FileSystemWAL truncates the WAL file to the checkpointed point after recovery > so this poses a problem. > WindowDataManager should be able to control recovery of FileSystemWAL. > 2. FileSystemWAL writes to temporary files. The mapping of temp files to > actual file is part of its state which is checkpointed. Since > WindowDataManager replays data of a window not yet checkpointed, it needs to > know the actual temporary file the data is being persisted to. -- This message was sent by Atlassian JIRA (v6.3.4#6332)