Re: Thread Safety in LMDB with MDB_NOTLS and Readonly Cursors

xiaoya2wei@gmail.com wrote:

Thanks Howard,

Then I guess I have 2 follow-up questions:

1. Just to confirm (something I didn't get a clear answer): when MDB_NOTLS is set, a cursor opened by a rw txn can be serially accessed by multiple threads, one at a time. Is this write?

No. MDB_NOTLS has no relevance to rw txns. The docs state quite clearly that it only affects read-only txns. Read more carefully.

2. What does "Cursors may not span transactions" specifically mean? In my understanding, a cursor belongs to one and only one txn, I didn't find an LMDB API that allows users to operate a cursor with some random transactions?

Read more carefully.