From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtpng3.m.smailru.net (smtpng3.m.smailru.net [94.100.177.149]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dev.tarantool.org (Postfix) with ESMTPS id 33E884696C3 for ; Fri, 14 Feb 2020 22:40:38 +0300 (MSK) From: Ilya Kosarev Date: Fri, 14 Feb 2020 22:40:30 +0300 Message-Id: Subject: [Tarantool-patches] [PATCH 0/4] Safe truncation and deletion List-Id: Tarantool development patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: tarantool-patches@dev.tarantool.org This patchset is an experiment on reserve tech used for safe truncation and the demonstration of the possible space:delete() fail on reserve. The idea of the 3rd patch (memtx: use reserved slab for truncation) was to prealloc a slab on arena to be used only for truncation tuples. This approach didn't really solve the problem. After we are getting the reserved slab with slab_map, we have a choice to put or not to put it on slab lists. In case we do put it, the problem is that any next operation, using mempool_alloc, will be able to use our slab, not only truncation. This will lead to it's fast exhaustion. On the other hand, if we skip all this lists (as it is done), we will fail at the garbage collection when trying to free those tuples, as far as their slab won't be found. See backtrace at https://gitlab.com/tarantool/tarantool/-/jobs/438082894. It doesn't look like there is any acceptable way to tune garbage collector behavior. In the 4th patch the stress_delete test with errinj is introduced to show how it may fail on reserve. It uses errinj to simulate the case where the num of reserved extents for memtx_index_extent_reserve won't be enough, setting target amount as current amount + 1. Not aimed to be pushed to master! Branch: https://github.com/tarantool/tarantool/tree/i.kosarev/gh-3807-safe-alloc-on-truncation Issue: https://github.com/tarantool/tarantool/issues/3807 Ilya Kosarev (4): small: bump small version b-tree: return NULL on matras_alloc fail memtx: use reserved slab for truncation memtx: space:delete() might fail on reserve src/box/box.cc | 27 ++++++- src/box/memtx_space.c | 15 +++- src/box/tuple.c | 4 + src/lib/core/errinj.h | 1 + src/lib/core/memory.c | 1 + src/lib/salad/bps_tree.h | 22 +++++- src/lib/small | 2 +- test/box/errinj.result | 1 + test/engine/engine.cfg | 6 ++ test/engine/low_memory.lua | 8 ++ test/engine/stress_delete.result | 111 +++++++++++++++++++++++++++ test/engine/stress_delete.test.lua | 55 +++++++++++++ test/engine/stress_truncate.result | 103 +++++++++++++++++++++++++ test/engine/stress_truncate.test.lua | 52 +++++++++++++ 14 files changed, 399 insertions(+), 9 deletions(-) create mode 100644 test/engine/low_memory.lua create mode 100644 test/engine/stress_delete.result create mode 100644 test/engine/stress_delete.test.lua create mode 100644 test/engine/stress_truncate.result create mode 100644 test/engine/stress_truncate.test.lua -- 2.17.1