Alexey Serbin has submitted this change and it was merged. ( http://gerrit.cloudera.org:8080/16928 )
Change subject: [transactions] remove cached TransactionEntry's state ...................................................................... [transactions] remove cached TransactionEntry's state With changelist fa21bf618, an atomic field was added to TransactionEntry to contain a cached state for an entry. The motivation was to provide lock-free access the state of the entry: accessing the metadata stored as a COW object in the 'metadata_' field involves taking read lock for that. The transaction keepalive tracking task needs to check the status of an entry every time it runs (10 seconds by default), and there may be many txn records records. However, that approach didn't provide an automatic update of the cached field upon modification of the underlying 'metadata_' object, and updating that manually proved to be cumbersome and bug prone. A few alternatives to update the cached field automatically were considered, but after realizing that we don't have hard data showing a lot of lock contention or resources spent on lock acquisition, the former approach was deemed to be a premature optimization. With this changelist, the cached field is removed and the TransactionEntry::state() accessor now takes a read lock to access the state of the transactional entry. Change-Id: Iab1ffe4312d21b732d7f37f7b54f28e43c979e35 Reviewed-on: http://gerrit.cloudera.org:8080/16928 Reviewed-by: Andrew Wong <aw...@cloudera.com> Tested-by: Kudu Jenkins --- M src/kudu/transactions/txn_status_entry.cc M src/kudu/transactions/txn_status_entry.h M src/kudu/transactions/txn_status_manager.cc 3 files changed, 9 insertions(+), 22 deletions(-) Approvals: Andrew Wong: Looks good to me, approved Kudu Jenkins: Verified -- To view, visit http://gerrit.cloudera.org:8080/16928 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: merged Gerrit-Change-Id: Iab1ffe4312d21b732d7f37f7b54f28e43c979e35 Gerrit-Change-Number: 16928 Gerrit-PatchSet: 2 Gerrit-Owner: Alexey Serbin <aser...@cloudera.com> Gerrit-Reviewer: Alexey Serbin <aser...@cloudera.com> Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com> Gerrit-Reviewer: Hao Hao <hao....@cloudera.com> Gerrit-Reviewer: Kudu Jenkins (120)
