memory leak issue fixed with jemalloc (#381)

Dockerfile

@@ -87,6 +87,15 @@ RUN DEBIAN_FRONTEND=noninteractive \
   apt-get clean && \
   rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 
+ADD https://github.com/jemalloc/jemalloc/releases/download/5.2.1/jemalloc-5.2.1.tar.bz2 /tmp/jemalloc-5.2.1.tar.bz2
+RUN apt-get update && apt install -y bzip2 gcc make autoconf
+RUN cd /tmp \
+    && tar -jxvf jemalloc-5.2.1.tar.bz2 --no-same-owner \
+    && cd jemalloc-5.2.1 \
+    && ./configure --enable-prof && make && make install \
+    && rm -rf /tmp/*
+ENV LD_PRELOAD=/usr/local/lib/libjemalloc.so
+
 # Server port to listen
 ENV PORT 9000