From e9c43b2b944a9378dc0ab708fd560cae9034c3f9 Mon Sep 17 00:00:00 2001
From: HappenLee <happenlee@hotmail.com>
Date: Fri, 18 Aug 2023 16:50:58 +0800
Subject: [PATCH] [Enhancement](scanner) allocate blocks in scanner_context on
 demand and free them on close

---
 be/src/vec/exec/scan/scanner_context.cpp | 16 ----------------
 be/src/vec/exec/scan/scanner_context.h   |  2 --
 2 files changed, 18 deletions(-)

diff --git a/be/src/vec/exec/scan/scanner_context.cpp b/be/src/vec/exec/scan/scanner_context.cpp
index 17bfbde79d5878..a08c81ad5e91d9 100644
--- a/be/src/vec/exec/scan/scanner_context.cpp
+++ b/be/src/vec/exec/scan/scanner_context.cpp
@@ -104,9 +104,6 @@ Status ScannerContext::init() {
             limit == -1 ? _batch_size : std::min(static_cast<int64_t>(_batch_size), limit);
     _block_per_scanner = (doris_scanner_row_num + (real_block_size - 1)) / real_block_size;
     _free_blocks_capacity = _max_thread_num * _block_per_scanner;
-    auto pre_alloc_block_count = _max_thread_num * _block_per_scanner;
-
-    _init_free_block(pre_alloc_block_count, real_block_size);
 
 #ifndef BE_TEST
     // 3. get thread token
@@ -126,19 +123,6 @@ Status ScannerContext::init() {
     return Status::OK();
 }
 
-void ScannerContext::_init_free_block(int pre_alloc_block_count, int real_block_size) {
-    // The free blocks is used for final output block of scanners.
-    // So use _output_tuple_desc;
-    int64_t free_blocks_memory_usage = 0;
-    for (int i = 0; i < pre_alloc_block_count; ++i) {
-        auto block = vectorized::Block::create_unique(_output_tuple_desc->slots(), real_block_size,
-                                                      true /*ignore invalid slots*/);
-        free_blocks_memory_usage += block->allocated_bytes();
-        _free_blocks.enqueue(std::move(block));
-    }
-    _free_blocks_memory_usage->add(free_blocks_memory_usage);
-}
-
 vectorized::BlockUPtr ScannerContext::get_free_block(bool* has_free_block,
                                                      bool get_block_not_empty) {
     vectorized::BlockUPtr block;
diff --git a/be/src/vec/exec/scan/scanner_context.h b/be/src/vec/exec/scan/scanner_context.h
index 202a15e4262005..6e86286b15f258 100644
--- a/be/src/vec/exec/scan/scanner_context.h
+++ b/be/src/vec/exec/scan/scanner_context.h
@@ -167,8 +167,6 @@ class ScannerContext {
 protected:
     virtual void _dispose_coloate_blocks_not_in_queue() {}
 
-    void _init_free_block(int pre_alloc_block_count, int real_block_size);
-
     RuntimeState* _state;
     VScanNode* _parent;