Introduced jemalloc (#5590)

### What problem does this PR solve?

Introduced jemalloc.
Python uses pymalloc (which is an reimplementation of gblibc malloc) to
manage RES. It has pools for small objects to avoid returning memory to
OS aggressively. My experience is: Replacing pymalloc with
[jemalloc](https://github.com/jemalloc/jemalloc) can reduce RES and
speedup task_executor.py.

### Type of change

- [x] Performance Improvement

docker/entrypoint-parser.sh

@@ -15,8 +15,9 @@ CONSUMER_NO_BEG=$1
 CONSUMER_NO_END=$2
 
 function task_exe(){
+    JEMALLOC_PATH=$(pkg-config --variable=libdir jemalloc)/libjemalloc.so
     while [ 1 -eq 1 ]; do
-      $PY rag/svr/task_executor.py $1;
+      LD_PRELOAD=$JEMALLOC_PATH $PY rag/svr/task_executor.py $1;
     done
 }
 

docker/entrypoint.sh

@@ -17,8 +17,9 @@ if [[ -z "$WS" || $WS -lt 1 ]]; then
 fi
 
 function task_exe(){
+    JEMALLOC_PATH=$(pkg-config --variable=libdir jemalloc)/libjemalloc.so
     while [ 1 -eq 1 ];do
-      $PY rag/svr/task_executor.py $1;
+      LD_PRELOAD=$JEMALLOC_PATH $PY rag/svr/task_executor.py $1;
     done
 }