steveloughran commented on pull request #2069: URL: https://github.com/apache/hadoop/pull/2069#issuecomment-687247574
OK, despite my force push losing @jimmy-zuber-amzn 's comments, I agree with the points about thread safety. In my head I'd imagined that we'd build that implementation map once and then iterate over it, but I can see benefits in supporting dynamic addition of new values to both the snapshot and the dynamic ones. Snapshot: add an entry to the map Dynamic: add new atomic long etc entries to the appropriate map this would let us create a minimal snapshot then pass it around, and as it was passed around it would collect values, *without you needing to define up front all stats to collect*. This work here needs to be lined up for that with iterators of maps being resilient to new values being added. For the dynamic stuff -> ConcurrentHashMap. For Snapshot, it's trickier as they need to be java serializable, so that Spark & can can forward them around. There I will have to do one of *mark the maps all as transient, and then in read/write data actually save then restore the data as treemaps (or just arrays of entries) * Make accessors to the iterators synchronized and do a snapshot of the iterator. I think that will actually be the easiest approach...I just need to make sure the operations to update the maps are also synchronized ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org
