Tim Armstrong has uploaded a new patch set (#7). Change subject: IMPALA-5169: Add support for async pins in buffer pool ......................................................................
IMPALA-5169: Add support for async pins in buffer pool Makes Pin() do async reads behind-the-scenes, instead of blocking until the read completes. The blocking is done instead when the client tries to access the buffer via PageHandle::GetBuffer() or ExtractBuffer(). This is implemented with a new sub-state of "pinned" where the page has a buffer and consumes reservation but the buffer does not contain valid data. Motivation: This unlocks various opportunities to overlap read I/Os with other work: * Reads to different disks can execute in parallel * I/O and computation can be overlapped. This initially benefits BufferedTupleStream::PinStream(), where many pages are pinned at once. With this change the reads run asynchronously. This can potentially lead to large speedups when spilling. E.g. if the pages for a Hash Join's partition are spread across 10 disks, we could get 10x the read throughput, plus overlap the I/O with hash table build. In future we can use this to do read-ahead over unpinned BufferedTupleStreams or for unpinned Runs in Sorter, but this requires changes to the client code to Pin() pages in advance. Testing: * BufferedTupleStreamV2 already exercises this. * Various BufferPool tests already exercise this. * Added a basic test to cover edge cases made possible by the new state transitions. * Extended the randomised test to cover this. Change-Id: Ibdf074c1ac4405d6f08d623ba438a85f7d39fd79 --- M be/src/runtime/buffered-tuple-stream-v2.cc M be/src/runtime/buffered-tuple-stream-v2.h M be/src/runtime/bufferpool/buffer-pool-internal.h M be/src/runtime/bufferpool/buffer-pool-test.cc M be/src/runtime/bufferpool/buffer-pool.cc M be/src/runtime/bufferpool/buffer-pool.h M be/src/runtime/tmp-file-mgr.cc M be/src/runtime/tmp-file-mgr.h 8 files changed, 418 insertions(+), 153 deletions(-) git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/12/6612/7 -- To view, visit http://gerrit.cloudera.org:8080/6612 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-MessageType: newpatchset Gerrit-Change-Id: Ibdf074c1ac4405d6f08d623ba438a85f7d39fd79 Gerrit-PatchSet: 7 Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-Owner: Tim Armstrong <tarmstr...@cloudera.com> Gerrit-Reviewer: Dan Hecht <dhe...@cloudera.com> Gerrit-Reviewer: Tim Armstrong <tarmstr...@cloudera.com>
