[enhencement](config) change default memtable size & loadStreamPerNod…

…e & default load parallelism (#28977)

We change memtable size from 200MB to 100MB to achieve smoother flush
performance. We change loadStreamPerNode from 20 to 60 to avoid stream
rpc to be the bottleneck when enable memtable_on_sink_node. We change
default s3&broker load parallelsim to make the most of CPUs on moderm
multi-core systems.

Signed-off-by: freemandealer <freeman.zhang1992@gmail.com>

be/src/common/config.cpp

@@ -592,7 +592,7 @@ DEFINE_Int32(memory_max_alignment, "16");
 // memtable insert memory tracker will multiply input block size with this ratio
 DEFINE_mDouble(memtable_insert_memory_ratio, "1.4");
 // max write buffer size before flush, default 200MB
-DEFINE_mInt64(write_buffer_size, "209715200");
+DEFINE_mInt64(write_buffer_size, "104857600");
 // max buffer size used in memtable for the aggregated table, default 400MB
 DEFINE_mInt64(write_buffer_size_for_agg, "419430400");
 // max parallel flush task per memtable writer

be/src/common/config.h

@@ -642,7 +642,7 @@ DECLARE_Int32(memory_max_alignment);
 
 // memtable insert memory tracker will multiply input block size with this ratio
 DECLARE_mDouble(memtable_insert_memory_ratio);
-// max write buffer size before flush, default 200MB
+// max write buffer size before flush, default 100MB
 DECLARE_mInt64(write_buffer_size);
 // max buffer size used in memtable for the aggregated table, default 400MB
 DECLARE_mInt64(write_buffer_size_for_agg);

docs/en/docs/admin-manual/config/fe-config.md

@@ -1153,7 +1153,7 @@ Max bytes a broker scanner can process in one broker load job. Commonly, each Ba
 
 #### `default_load_parallelism`
 
-Default: 1
+Default: 8
 
 IsMutable：true
 

docs/zh-CN/docs/admin-manual/config/fe-config.md

@@ -1154,7 +1154,7 @@ broker scanner 程序可以在一个 broker 加载作业中处理的最大字节
 
 #### `default_load_parallelism`
 
-默认值：1
+默认值：8
 
 是否可以动态配置：true
 

fe/fe-common/src/main/java/org/apache/doris/common/Config.java

@@ -144,7 +144,7 @@ public class Config extends ConfigBase {
 
     @ConfField(mutable = true, masterOnly = true, description = {"broker load 时，单个节点上 load 执行计划的默认并行度",
             "The default parallelism of the load execution plan on a single node when the broker load is submitted"})
-    public static int default_load_parallelism = 1;
+    public static int default_load_parallelism = 8;
 
     @ConfField(mutable = true, masterOnly = true, description = {
             "已完成或取消的导入作业信息的 label 会在这个时间后被删除。被删除的 label 可以被重用。",

fe/fe-core/src/main/java/org/apache/doris/qe/SessionVariable.java

@@ -1325,7 +1325,7 @@ public void setEnableLeftZigZag(boolean enableLeftZigZag) {
     public boolean enableMemtableOnSinkNode = true;
 
     @VariableMgr.VarAttr(name = LOAD_STREAM_PER_NODE)
-    public int loadStreamPerNode = 20;
+    public int loadStreamPerNode = 60;
 
     @VariableMgr.VarAttr(name = GROUP_COMMIT)
     public String groupCommit = "off_mode";