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Fix: defragment_sys_variable has memory allocation failure wild pointer problem

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This commit is contained in:
obdev
2023-02-20 10:11:47 +00:00
committed by ob-robot
parent 61cb178902
commit 429bde73a6
2 changed files with 61 additions and 23 deletions
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74
src/sql/session/ob_basic_session_info.cpp
View File

@ -91,7 +91,9 @@ ObBasicSessionInfo::ObBasicSessionInfo()
trans_flags_(),
sql_scope_flags_(),
base_sys_var_alloc_(ObModIds::OB_SQL_SESSION, OB_MALLOC_NORMAL_BLOCK_SIZE),
inc_sys_var_alloc_(ObModIds::OB_SQL_SESSION, OB_MALLOC_NORMAL_BLOCK_SIZE),
inc_sys_var_alloc1_(ObModIds::OB_SQL_SESSION, OB_MALLOC_NORMAL_BLOCK_SIZE),
inc_sys_var_alloc2_(ObModIds::OB_SQL_SESSION, OB_MALLOC_NORMAL_BLOCK_SIZE),
current_buf_index_(0),
bucket_allocator_wrapper_(&block_allocator_),
user_var_val_map_(SMALL_BLOCK_SIZE, ObWrapperAllocator(&block_allocator_)),
influence_plan_var_indexs_(),
@ -151,6 +153,8 @@ ObBasicSessionInfo::ObBasicSessionInfo()
CHAR_CARRAY_INIT(trace_id_buff_);
ssl_cipher_buff_[0] = '\0';
sess_bt_buff_[0] = '\0';
inc_sys_var_alloc_[0] = &inc_sys_var_alloc1_;
inc_sys_var_alloc_[1] = &inc_sys_var_alloc2_;
}
ObBasicSessionInfo::~ObBasicSessionInfo()
@ -411,7 +415,9 @@ void ObBasicSessionInfo::reset(bool skip_sys_var)
// 最后再重置所有allocator
// 否则thread_data_.user_name_之类的属性会有野指针，在session_mgr的foreach接口遍历时可能core掉。
name_pool_.reset();
inc_sys_var_alloc_.reset();
inc_sys_var_alloc1_.reset();
inc_sys_var_alloc2_.reset();
current_buf_index_ = 0;
if (!skip_sys_var) {
base_sys_var_alloc_.reset();
sys_var_fac_.destroy();
@ -1741,7 +1747,7 @@ int ObBasicSessionInfo::deep_copy_sys_variable(ObBasicSysVar &sys_var,
sys_var.set_value(dest_val);
}
} else {
if (OB_FAIL(inc_sys_var_alloc_.write_obj(src_val, &dest_val))) {
if (OB_FAIL(inc_sys_var_alloc_[current_buf_index_]->write_obj(src_val, &dest_val))) {
LOG_WARN("fail to write obj", K(src_val), K(ret));
} else {
if (ob_is_string_type(src_val.get_type())) {
@ -1755,23 +1761,30 @@ int ObBasicSessionInfo::deep_copy_sys_variable(ObBasicSysVar &sys_var,
// defragment.
// https://work.aone.alibaba-inc.com/issue/39958139
// Double buffer optimization
// https://work.aone.alibaba-inc.com/issue/47795403
// Double buffer optimization uses two buffers to cyclically store
// system variable values. If the currently used buffer reaches the
// upper limit, the variable value will be defragmented and stored
// in another buffer, which can avoid the failure of using one buffer
// to store in the temporary buffer and cause wild pointer problem.
if (OB_SUCC(ret)) {
if (inc_sys_var_alloc_.used() > next_frag_mem_point_) {
// Note: this defrag impl. algrothim is not efficient.
// howerver, considering it is not the common path, we don't expect to be here very often.
// for an efficient impl. please refer https://yuque.antfin-inc.com/xiaochu.yh/doc/oa9az6
common::ObStringBuf tmp_buf(ObModIds::OB_SQL_SESSION, OB_MALLOC_NORMAL_BLOCK_SIZE);
if (OB_FAIL(defragment_sys_variable_to(tmp_buf))) {
if (inc_sys_var_alloc_[current_buf_index_]->used() > next_frag_mem_point_) {
// Double buffer optimization
// tmp_value storage tmp dest_val.
ObArray<std::pair<int64_t, ObObj>> tmp_value;
if (OB_FAIL(defragment_sys_variable_from(tmp_value))) {
LOG_WARN("fail to defrag sys variable memory to temp alloc", K(ret));
} else {
int32_t next_index = (current_buf_index_ == 0 ? 1 : 0);
LOG_INFO("Too much memory used for system variable values. do defragment",
"before", inc_sys_var_alloc_.used(), "after", tmp_buf.used());
inc_sys_var_alloc_.reset();
if (OB_FAIL(defragment_sys_variable_to(inc_sys_var_alloc_))) {
LOG_WARN("fail to defrag sys variable memory to base sys var alloc", K(ret));
} else {
next_frag_mem_point_ = std::max(2 * inc_sys_var_alloc_.used(), OB_MALLOC_NORMAL_BLOCK_SIZE);
}
"before", inc_sys_var_alloc_[current_buf_index_]->used(),
"after", inc_sys_var_alloc_[next_index]->used());
defragment_sys_variable_to(tmp_value);
inc_sys_var_alloc_[current_buf_index_]->reset();
current_buf_index_ = next_index;
next_frag_mem_point_ = std::max(2 * inc_sys_var_alloc_[next_index]->used(),
OB_MALLOC_NORMAL_BLOCK_SIZE);
}
}
}
@ -1779,11 +1792,13 @@ int ObBasicSessionInfo::deep_copy_sys_variable(ObBasicSysVar &sys_var,
return ret;
}
int ObBasicSessionInfo::defragment_sys_variable_to(common::ObStringBuf &allocator)
// buf2 write_obj for defragment_sys_variable and push dest_val into tmp_value.
int ObBasicSessionInfo::defragment_sys_variable_from(ObArray<std::pair<int64_t, ObObj>> &tmp_value)
{
int ret = OB_SUCCESS;
const SysVarIds &all_sys_var_ids = sys_var_inc_info_.get_all_sys_var_ids();
for (int i = 0; OB_SUCC(ret) && i < all_sys_var_ids.count(); i++) {
int32_t next_index = (current_buf_index_ == 0 ? 1 : 0);
for (int64_t i = 0; OB_SUCC(ret) && i < all_sys_var_ids.count(); i++) {
int64_t store_idx = -1;
ObSysVarClassType sys_var_id = all_sys_var_ids.at(i);
OZ (ObSysVarFactory::calc_sys_var_store_idx(sys_var_id, store_idx));
@ -1793,17 +1808,32 @@ int ObBasicSessionInfo::defragment_sys_variable_to(common::ObStringBuf &allocato
const ObObj &src_val = sys_vars_[store_idx]->get_value();
if (ob_is_string_type(src_val.get_type()) || ob_is_number_tc(src_val.get_type())) {
ObObj dest_val;
if (OB_FAIL(allocator.write_obj(src_val, &dest_val))) {
if (OB_FAIL(inc_sys_var_alloc_[next_index]->write_obj(src_val, &dest_val))) {
LOG_WARN("fail to write obj", K(src_val), K(ret));
} else if (OB_FAIL(tmp_value.push_back(std::pair<int64_t, ObObj>(store_idx, dest_val)))){
LOG_WARN("fail to push back tmp_value", K(ret));
} else {
sys_vars_[store_idx]->set_value(dest_val);
LOG_DEBUG("success to push back tmp value", K(ret), K(store_idx), K(dest_val));
}
}
}
if (OB_FAIL(ret)) {
inc_sys_var_alloc_[next_index]->reset();
}
}
return ret;
}
// sys_vars_ set value.
void ObBasicSessionInfo::defragment_sys_variable_to(ObArray<std::pair<int64_t, ObObj>> &tmp_value)
{
for (int64_t i = 0; i < tmp_value.count(); i++) {
sys_vars_[tmp_value.at(i).first]->set_value(tmp_value.at(i).second);
}
}
int ObBasicSessionInfo::update_session_sys_variable(ObExecContext &ctx,
const ObString &var,
const ObObj &val)
@ -4423,7 +4453,9 @@ int ObBasicSessionInfo::clean_all_sys_vars()
}
}
OX (base_sys_var_alloc_.reset());
OX (inc_sys_var_alloc_.reset());
OX (inc_sys_var_alloc1_.reset());
OX (inc_sys_var_alloc2_.reset());
current_buf_index_ = 0;
return ret;
}

10
src/sql/session/ob_basic_session_info.h
View File

@ -1327,7 +1327,8 @@ private:
int deep_copy_sys_variable(share::ObBasicSysVar &sys_var,
const share::ObSysVarClassType sys_var_id,
const common::ObObj &src_val);
int defragment_sys_variable_to(common::ObStringBuf &allocator);
int defragment_sys_variable_from(ObArray<std::pair<int64_t, ObObj>> &tmp_value);
void defragment_sys_variable_to(ObArray<std::pair<int64_t, ObObj>> &tmp_value);
int deep_copy_trace_id_var(const common::ObObj &src_val,
common::ObObj *dest_val_ptr);
inline int store_query_string_(const ObString &stmt);
@ -1933,7 +1934,12 @@ protected:
private:
common::ObStringBuf base_sys_var_alloc_; // for variables names and statement names
common::ObStringBuf inc_sys_var_alloc_; // for values in sys variables update
// Double buffer optimization
common::ObStringBuf *inc_sys_var_alloc_[2]; // for values in sys variables update
common::ObStringBuf inc_sys_var_alloc1_; // for values in sys variables update
common::ObStringBuf inc_sys_var_alloc2_; // for values in sys variables update
int32_t current_buf_index_; // for record current buf index
// Double buffer optimization end.
common::ObWrapperAllocator bucket_allocator_wrapper_;
ObSessionValMap user_var_val_map_; // user variables
share::ObBasicSysVar *sys_vars_[share::ObSysVarFactory::ALL_SYS_VARS_COUNT]; // system variables