github@nicwatson.org wrote:

Full_Name: Nic Watson Version: LMDB v 0.9.21 OS: Ubuntu 17.04 URL: ftp://ftp.openldap.org/incoming/ Submission from: (NULL) (108.56.136.246)

I'm getting a seg fault in using LMDB on a database opened with MDB_DUPSORT.

Here's a minimal set of operations that will cause the problem:

It will *not* crash under debug. In fact, -O3 -fvect-cost-model=cheap will *not* crash. This makes some sense since it is crashing on an SSE instruction.

I tried gcc versions (Ubuntu 7.2.0-8ubuntu3.2) and (Ubuntu 6.4.0-8ubuntu1) with the same result. I also tried with the mdb.master branch (0.9.70) with the same result.

I'm not convinced this a fault in your code. It may be a gcc bug.

Interesting. I've got gcc 5.4.0 on Ubuntu 16.04 here, and no crash. Also rather puzzled that there's anything vectorizable in this code, that seems pretty unlikely.