[Tarantool-patches] [PATCH v4] memtx: change small allocator behavior

[mechanik20051988 <mechanik20051988@tarantool.org>]

From: mechanik20051988 <mechanik20.05.1988@gmail.com>

Branch: https://github.com/tarantool/tarantool/tree/mechanik20051988/gh-5216-fix-strange-allocator-behavior

Cnanges in v4:
	Add actual_alloc_factor parameter to small_alloc_create

Previously, in small allocator, memory pools
were allocated at the request, which in the case
of a small slab_alloc_factor led to use
pools with incorrect sizes. This patch changed
small allocator behavior, now we allocate pools
on the stage of allocator creation. Also we use
special function to find appropriate pool, which
is faster, then previous version with rbtree.
This change fixes #5216.

Also moved a check, that the slab_alloc_factor is in
the range (1.0, 2.0] from small allocator to memtx_engine.
If factor is not in range change it to 1.0001 or 2.0 respectively

Closes #5216
---
 src/box/memtx_engine.c                        | 12 +++-
 src/box/tuple.c                               |  3 +-
 src/lib/small                                 |  2 +-
 test/engine/engine.cfg                        |  3 +
 test/engine/gh-5216-small_alloc_factor.lua    | 11 +++
 test/engine/gh-5216-small_alloc_factor.result | 70 +++++++++++++++++++
 .../gh-5216-small_alloc_factor.test.lua       | 20 ++++++
 7 files changed, 118 insertions(+), 3 deletions(-)
 create mode 100644 test/engine/gh-5216-small_alloc_factor.lua
 create mode 100644 test/engine/gh-5216-small_alloc_factor.result
 create mode 100644 test/engine/gh-5216-small_alloc_factor.test.lua

diff --git a/src/box/memtx_engine.c b/src/box/memtx_engine.c
index 4f1fe3a3f..023402888 100644
--- a/src/box/memtx_engine.c
+++ b/src/box/memtx_engine.c
@@ -1116,13 +1116,23 @@ memtx_engine_new(const char *snap_dirname, bool force_recovery,
 	if (objsize_min < OBJSIZE_MIN)
 		objsize_min = OBJSIZE_MIN;
 
+	if (alloc_factor > 2) {
+		say_error("Alloc factor must be less than or equal to 2.0. It will be reduced to 2.0");
+		alloc_factor = 2.0;
+	} else if (alloc_factor <= 1.0) {
+		say_error("Alloc factor must be greater than 1.0. It will be increased to 1.001");
+		alloc_factor = 1.001;
+	}
+
 	/* Initialize tuple allocator. */
 	quota_init(&memtx->quota, tuple_arena_max_size);
 	tuple_arena_create(&memtx->arena, &memtx->quota, tuple_arena_max_size,
 			   SLAB_SIZE, dontdump, "memtx");
 	slab_cache_create(&memtx->slab_cache, &memtx->arena);
+	float actual_alloc_factor;
 	small_alloc_create(&memtx->alloc, &memtx->slab_cache,
-			   objsize_min, alloc_factor);
+			   objsize_min, alloc_factor, &actual_alloc_factor);
+	say_info("Actual alloc factor calculated on the basis of desired alloc_factor = %f", actual_alloc_factor);
 
 	/* Initialize index extent allocator. */
 	slab_cache_create(&memtx->index_slab_cache, &memtx->arena);
diff --git a/src/box/tuple.c b/src/box/tuple.c
index e83377c3a..c2023e4e8 100644
--- a/src/box/tuple.c
+++ b/src/box/tuple.c
@@ -313,8 +313,9 @@ tuple_init(field_name_hash_f hash)
 	/* Make sure this one stays around. */
 	tuple_format_ref(tuple_format_runtime);
 
+	float actual_alloc_factor;
 	small_alloc_create(&runtime_alloc, &cord()->slabc, OBJSIZE_MIN,
-			   ALLOC_FACTOR);
+			   ALLOC_FACTOR, &actual_alloc_factor);
 
 	mempool_create(&tuple_iterator_pool, &cord()->slabc,
 		       sizeof(struct tuple_iterator));
diff --git a/src/lib/small b/src/lib/small
index fcac155db..bdbe73cd3 160000
--- a/src/lib/small
+++ b/src/lib/small
@@ -1 +1 @@
-Subproject commit fcac155dba18e97b10bc668d1a2fae01184adc13
+Subproject commit bdbe73cd35865160dd9f80bfc8bfa3817f4980aa
diff --git a/test/engine/engine.cfg b/test/engine/engine.cfg
index f017a03ec..3bfc44dcf 100644
--- a/test/engine/engine.cfg
+++ b/test/engine/engine.cfg
@@ -8,6 +8,9 @@
     },
     "gh-4973-concurrent-alter-fails.test.lua": {
         "memtx": {"engine": "memtx"}
+    },
+    "gh-5216-small_alloc_factor.test.lua" : {
+        "memtx": {"engine": "memtx"}
     }
 }
 
diff --git a/test/engine/gh-5216-small_alloc_factor.lua b/test/engine/gh-5216-small_alloc_factor.lua
new file mode 100644
index 000000000..a303a95d4
--- /dev/null
+++ b/test/engine/gh-5216-small_alloc_factor.lua
@@ -0,0 +1,11 @@
+#!/usr/bin/env tarantool
+
+require('console').listen(os.getenv('ADMIN'))
+
+box.cfg({
+    wal_mode = 'none',
+    memtx_memory = 2*1024*1024*1024,
+    listen = os.getenv("LISTEN"),
+    memtx_min_tuple_size=32,
+    slab_alloc_factor=1.03
+})
diff --git a/test/engine/gh-5216-small_alloc_factor.result b/test/engine/gh-5216-small_alloc_factor.result
new file mode 100644
index 000000000..5cf69a8f3
--- /dev/null
+++ b/test/engine/gh-5216-small_alloc_factor.result
@@ -0,0 +1,70 @@
+env = require('test_run')
+---
+...
+test_run = env.new()
+---
+...
+test_run:cmd('create server test with script="engine/gh-5216-small_alloc_factor.lua"')
+---
+- true
+...
+test_run:cmd('start server test with args="none"')
+---
+- true
+...
+test_run:cmd('switch test')
+---
+- true
+...
+s = box.schema.space.create('test')
+---
+...
+_ = s:create_index('test')
+---
+...
+function str(i) return string.rep('a', math.floor(256 * math.pow(1.03, i))) end
+---
+...
+for i=1,276 do _ = s:replace{i+200, str(i)} end
+---
+...
+for i=1,274 do _ = s:delete{i+200} end
+---
+...
+collectgarbage('collect')
+---
+- 0
+...
+_ = s:replace{200+277, str(275)}
+---
+...
+_ = s:delete{200+275}
+---
+...
+collectgarbage('collect')
+---
+- 0
+...
+_ = s:delete{200+276}
+---
+...
+collectgarbage('collect')
+---
+- 0
+...
+test_run:cmd('switch default')
+---
+- true
+...
+test_run:cmd('stop server test')
+---
+- true
+...
+test_run:cmd('cleanup server test')
+---
+- true
+...
+test_run:cmd('delete server test')
+---
+- true
+...
diff --git a/test/engine/gh-5216-small_alloc_factor.test.lua b/test/engine/gh-5216-small_alloc_factor.test.lua
new file mode 100644
index 000000000..83e51d19c
--- /dev/null
+++ b/test/engine/gh-5216-small_alloc_factor.test.lua
@@ -0,0 +1,20 @@
+env = require('test_run')
+test_run = env.new()
+test_run:cmd('create server test with script="engine/gh-5216-small_alloc_factor.lua"')
+test_run:cmd('start server test with args="none"')
+test_run:cmd('switch test')
+s = box.schema.space.create('test')
+_ = s:create_index('test')
+function str(i) return string.rep('a', math.floor(256 * math.pow(1.03, i))) end
+for i=1,276 do _ = s:replace{i+200, str(i)} end
+for i=1,274 do _ = s:delete{i+200} end
+collectgarbage('collect')
+_ = s:replace{200+277, str(275)}
+_ = s:delete{200+275}
+collectgarbage('collect')
+_ = s:delete{200+276}
+collectgarbage('collect')
+test_run:cmd('switch default')
+test_run:cmd('stop server test')
+test_run:cmd('cleanup server test')
+test_run:cmd('delete server test')
-- 
2.20.1