[PATCH v5 2/2] box/memtx: Allow to skip tuple memory from coredump

[Cyrill Gorcunov <gorcunov@gmail.com>]

In case if there are huge amount of tuples the whole
memory goes to coredump file even if we don't need it
for problem investigation. In result coredump may
blow up to gigabytes in size.

Lets allow to exclude this memory from dumping via
box.cfg::strip_core boolean parameter.

Note that the tuple's arena is used not only for tuples
themselves but for memtx->index_extent_pool and
memtx->iterator_pool as well, so they are affected
too.

Fixes #3509

@TarantoolBot document
Title: Document box.cfg.strip_core

When Tarantool runs under a heavy load the memory allocated
for tuples may be very huge in size and to eliminate this
memory from being present in `coredump` file the `box.cfg.strip_core`
parameter should be set to `true`.

The default value is `false`.
---
v2:
 - Use strip_core name for box parameter
 - Pass cfg_geti directly to functions
 - vy_mem_env_create for now left as it was,
   simply because we can't use cfg_geti there
   (linking with library fails), I think we can
   address it on top later
v5:
 - Cover all code with new SLAB_ARENA_FLAG_ entries
   (actually there was one place only: memory_init)
 - In load_cfg do test if we support SMALL_FEATURE_DONTDUMP
   runtime and print a warning if we not.

 src/box/box.cc           |  1 +
 src/box/lua/load_cfg.lua |  2 ++
 src/box/memtx_engine.c   |  4 ++--
 src/box/memtx_engine.h   |  9 ++++++---
 src/box/tuple.c          | 15 ++++++++++++---
 src/box/tuple.h          |  2 +-
 src/box/vy_mem.c         |  2 +-
 src/lib/core/memory.c    |  2 +-
 src/main.cc              | 12 ++++++++++++
 test/box/admin.result    |  2 ++
 test/box/cfg.result      |  4 ++++
 11 files changed, 44 insertions(+), 11 deletions(-)

diff --git a/src/box/box.cc b/src/box/box.cc
index 7828f575b..57419ee01 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -1681,6 +1681,7 @@ engine_init()
 				    cfg_geti("force_recovery"),
 				    cfg_getd("memtx_memory"),
 				    cfg_geti("memtx_min_tuple_size"),
+				    cfg_geti("strip_core"),
 				    cfg_getd("slab_alloc_factor"));
 	engine_register((struct engine *)memtx);
 	box_set_memtx_max_tuple_size();
diff --git a/src/box/lua/load_cfg.lua b/src/box/lua/load_cfg.lua
index 5530b2caa..9f3344da3 100644
--- a/src/box/lua/load_cfg.lua
+++ b/src/box/lua/load_cfg.lua
@@ -25,6 +25,7 @@ end
 local default_cfg = {
     listen              = nil,
     memtx_memory        = 256 * 1024 *1024,
+    strip_core          = false,
     memtx_min_tuple_size = 16,
     memtx_max_tuple_size = 1024 * 1024,
     slab_alloc_factor   = 1.05,
@@ -88,6 +89,7 @@ local default_cfg = {
 local template_cfg = {
     listen              = 'string, number',
     memtx_memory        = 'number',
+    strip_core          = 'boolean',
     memtx_min_tuple_size  = 'number',
     memtx_max_tuple_size  = 'number',
     slab_alloc_factor   = 'number',
diff --git a/src/box/memtx_engine.c b/src/box/memtx_engine.c
index 25e800341..f4312484a 100644
--- a/src/box/memtx_engine.c
+++ b/src/box/memtx_engine.c
@@ -1011,7 +1011,7 @@ memtx_engine_gc_f(va_list va)
 struct memtx_engine *
 memtx_engine_new(const char *snap_dirname, bool force_recovery,
 		 uint64_t tuple_arena_max_size, uint32_t objsize_min,
-		 float alloc_factor)
+		 bool dontdump, float alloc_factor)
 {
 	struct memtx_engine *memtx = calloc(1, sizeof(*memtx));
 	if (memtx == NULL) {
@@ -1066,7 +1066,7 @@ memtx_engine_new(const char *snap_dirname, bool force_recovery,
 	/* Initialize tuple allocator. */
 	quota_init(&memtx->quota, tuple_arena_max_size);
 	tuple_arena_create(&memtx->arena, &memtx->quota, tuple_arena_max_size,
-			   SLAB_SIZE, "memtx");
+			   SLAB_SIZE, dontdump, "memtx");
 	slab_cache_create(&memtx->slab_cache, &memtx->arena);
 	small_alloc_create(&memtx->alloc, &memtx->slab_cache,
 			   objsize_min, alloc_factor);
diff --git a/src/box/memtx_engine.h b/src/box/memtx_engine.h
index 8f4ce7cdd..ccb51678d 100644
--- a/src/box/memtx_engine.h
+++ b/src/box/memtx_engine.h
@@ -189,7 +189,8 @@ memtx_engine_schedule_gc(struct memtx_engine *memtx,
 struct memtx_engine *
 memtx_engine_new(const char *snap_dirname, bool force_recovery,
 		 uint64_t tuple_arena_max_size,
-		 uint32_t objsize_min, float alloc_factor);
+		 uint32_t objsize_min, bool dontdump,
+		 float alloc_factor);
 
 int
 memtx_engine_recover_snapshot(struct memtx_engine *memtx,
@@ -257,12 +258,14 @@ memtx_index_def_change_requires_rebuild(struct index *index,
 static inline struct memtx_engine *
 memtx_engine_new_xc(const char *snap_dirname, bool force_recovery,
 		    uint64_t tuple_arena_max_size,
-		    uint32_t objsize_min, float alloc_factor)
+		    uint32_t objsize_min, bool dontdump,
+		    float alloc_factor)
 {
 	struct memtx_engine *memtx;
 	memtx = memtx_engine_new(snap_dirname, force_recovery,
 				 tuple_arena_max_size,
-				 objsize_min, alloc_factor);
+				 objsize_min, dontdump,
+				 alloc_factor);
 	if (memtx == NULL)
 		diag_raise();
 	return memtx;
diff --git a/src/box/tuple.c b/src/box/tuple.c
index 45c6727a4..a7ef332b2 100644
--- a/src/box/tuple.c
+++ b/src/box/tuple.c
@@ -323,7 +323,7 @@ tuple_init(field_name_hash_f hash)
 void
 tuple_arena_create(struct slab_arena *arena, struct quota *quota,
 		   uint64_t arena_max_size, uint32_t slab_size,
-		   const char *arena_name)
+		   bool dontdump, const char *arena_name)
 {
 	/*
 	 * Ensure that quota is a multiple of slab_size, to
@@ -331,11 +331,17 @@ tuple_arena_create(struct slab_arena *arena, struct quota *quota,
 	 */
 	size_t prealloc = small_align(arena_max_size, slab_size);
 
+        /*
+         * Skip from coredump if requested.
+         */
+        int flags = SLAB_ARENA_PRIVATE;
+        if (dontdump)
+                flags |= SLAB_ARENA_DONTDUMP;
+
 	say_info("mapping %zu bytes for %s tuple arena...", prealloc,
 		 arena_name);
 
-	if (slab_arena_create(arena, quota, prealloc, slab_size,
-			      MAP_PRIVATE) != 0) {
+	if (slab_arena_create(arena, quota, prealloc, slab_size, flags) != 0) {
 		if (errno == ENOMEM) {
 			panic("failed to preallocate %zu bytes: Cannot "\
 			      "allocate memory, check option '%s_memory' in box.cfg(..)", prealloc,
@@ -345,6 +351,9 @@ tuple_arena_create(struct slab_arena *arena, struct quota *quota,
 				       " tuple arena", prealloc, arena_name);
 		}
 	}
+
+	say_debug("tuple arena %s: addr %p size %zu flags %#x dontdump %d",
+		  arena_name, arena->arena, prealloc, flags, dontdump);
 }
 
 void
diff --git a/src/box/tuple.h b/src/box/tuple.h
index 0d950940d..99dfeb82d 100644
--- a/src/box/tuple.h
+++ b/src/box/tuple.h
@@ -70,7 +70,7 @@ tuple_free(void);
 void
 tuple_arena_create(struct slab_arena *arena, struct quota *quota,
 		   uint64_t arena_max_size, uint32_t slab_size,
-		   const char *arena_name);
+		   bool dontdump, const char *arena_name);
 
 void
 tuple_arena_destroy(struct slab_arena *arena);
diff --git a/src/box/vy_mem.c b/src/box/vy_mem.c
index a4fae26e2..b4d016a68 100644
--- a/src/box/vy_mem.c
+++ b/src/box/vy_mem.c
@@ -54,7 +54,7 @@ vy_mem_env_create(struct vy_mem_env *env, size_t memory)
 	/* Vinyl memory is limited by vy_quota. */
 	quota_init(&env->quota, QUOTA_MAX);
 	tuple_arena_create(&env->arena, &env->quota, memory,
-			   SLAB_SIZE, "vinyl");
+			   SLAB_SIZE, false, "vinyl");
 	lsregion_create(&env->allocator, &env->arena);
 	env->tree_extent_size = 0;
 }
diff --git a/src/lib/core/memory.c b/src/lib/core/memory.c
index 059304e34..f236c1887 100644
--- a/src/lib/core/memory.c
+++ b/src/lib/core/memory.c
@@ -43,7 +43,7 @@ memory_init()
 
 	/* No limit on the runtime memory. */
 	slab_arena_create(&runtime, &runtime_quota, 0,
-			  SLAB_SIZE, MAP_PRIVATE);
+			  SLAB_SIZE, SLAB_ARENA_PRIVATE);
 }
 
 void
diff --git a/src/main.cc b/src/main.cc
index 606c64c13..569ff4b5f 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -65,6 +65,7 @@
 #include "lua/init.h"
 #include "box/box.h"
 #include "box/error.h"
+#include "small/features.h"
 #include "scoped_guard.h"
 #include "random.h"
 #include "cfg.h"
@@ -488,6 +489,17 @@ load_cfg()
 #endif
 	}
 
+	/*
+	 * If we're requested to strip coredump
+	 * make sure we can do that, otherwise
+	 * require user to not turn it on.
+	 */
+	if (cfg_geti("strip_core")) {
+		if (!small_test_feature(SMALL_FEATURE_DONTDUMP)) {
+			say_warn("'strip_core' is set but unsupported");
+		}
+	}
+
 	int background = cfg_geti("background");
 	const char *log = cfg_gets("log");
 	const char *log_format = cfg_gets("log_format");
diff --git a/test/box/admin.result b/test/box/admin.result
index 53ced2fcc..bbebbd224 100644
--- a/test/box/admin.result
+++ b/test/box/admin.result
@@ -84,6 +84,8 @@ cfg_filter(box.cfg)
     - 500000
   - - slab_alloc_factor
     - 1.05
+  - - strip_core
+    - false
   - - too_long_threshold
     - 0.5
   - - vinyl_bloom_fpr
diff --git a/test/box/cfg.result b/test/box/cfg.result
index 66b02f591..81f4afac8 100644
--- a/test/box/cfg.result
+++ b/test/box/cfg.result
@@ -72,6 +72,8 @@ cfg_filter(box.cfg)
     - 500000
   - - slab_alloc_factor
     - 1.05
+  - - strip_core
+    - false
   - - too_long_threshold
     - 0.5
   - - vinyl_bloom_fpr
@@ -171,6 +173,8 @@ cfg_filter(box.cfg)
     - 500000
   - - slab_alloc_factor
     - 1.05
+  - - strip_core
+    - false
   - - too_long_threshold
     - 0.5
   - - vinyl_bloom_fpr
-- 
2.20.1