Use uvloop

Resolves https://github.com/spesmilo/electrumx/issues/92

Dockerfile

@@ -9,7 +9,7 @@ RUN VERSION=$(cat /tmp/VERSION) && \
     apk add --no-cache git build-base openssl && \
     apk add --no-cache --repository http://dl-cdn.alpinelinux.org/alpine/v3.11/main leveldb-dev && \
     apk add --no-cache --repository http://dl-cdn.alpinelinux.org/alpine/edge/testing rocksdb-dev && \
-    pip install aiohttp pylru plyvel websockets python-rocksdb && \
+    pip install aiohttp pylru plyvel websockets python-rocksdb uvloop && \
     git clone -b $VERSION https://github.com/spesmilo/electrumx.git && \
     cd electrumx && \
     python setup.py install && \
@@ -19,6 +19,7 @@ RUN VERSION=$(cat /tmp/VERSION) && \
 VOLUME ["/data"]
 ENV HOME /data
 ENV ALLOW_ROOT 1
+ENV EVENT_LOOP_POLICY uvloop
 ENV DB_DIRECTORY /data
 ENV SERVICES=tcp://:50001,ssl://:50002,wss://:50004,rpc://0.0.0.0:8000
 ENV SSL_CERTFILE ${DB_DIRECTORY}/electrumx.crt