Improve concurrency

- Update Python to use async/await
- Use asyncpg
- Use connection pool

Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.4
+FROM python:3.7
 RUN mkdir -p /usr/src/app
 WORKDIR /usr/src/app
 

requirements.txt

@@ -1,6 +1,6 @@
-tornado==4.4.2
-sqlalchemy==1.1.5
-mercantile==0.9.0
-pyproj==1.9.5.1
-pyyaml==3.12
-psycopg2==2.6.2
+asyncpg==0.19.0
+Click==7.0
+mercantile==1.1.2
+pyproj==2.4.0
+PyYAML==5.1.2
+tornado==6.0.3

server.py

@@ -1,47 +1,38 @@
-import tornado.ioloop
-import tornado.web
+import asyncpg
 import io
 import os
 
-from sqlalchemy import Column, ForeignKey, Integer, String
-from sqlalchemy.ext.declarative import declarative_base
-from sqlalchemy.orm import relationship
-from sqlalchemy import create_engine
-from sqlalchemy import inspect
-from sqlalchemy import text
-from sqlalchemy.orm import sessionmaker
-
+import logging
+import tornado
+import tornado.web
+from tornado.log import enable_pretty_logging
 import mercantile
 import pyproj
 import yaml
 import sys
 import itertools
 
+log = logging.getLogger('tornado.application')
+
 def GetTM2Source(file):
     with open(file,'r') as stream:
         tm2source = yaml.load(stream)
     return tm2source
 
-def GeneratePrepared(layers):
+def GenerateFunction(layers):
     queries = []
-    prepared = "PREPARE gettile(geometry, numeric, numeric, numeric) AS "
+    function = "CREATE OR REPLACE FUNCTION gettile(geometry, numeric, numeric, numeric) RETURNS SETOF bytea AS $$"
     for layer in layers['Layer']:
-        layer_query = layer['Datasource']['table'].lstrip().rstrip()	# Remove lead and trailing whitespace
+        layer_query = layer['Datasource']['table'].strip()
         layer_query = layer_query[1:len(layer_query)-6]			# Remove enough characters to remove first and last () and "AS t"
         layer_query = layer_query.replace("geometry", "ST_AsMVTGeom(geometry,!bbox!,4096,0,true) AS mvtgeometry")
         base_query = "SELECT ST_ASMVT('"+layer['id']+"', 4096, 'mvtgeometry', tile) FROM ("+layer_query+" WHERE ST_AsMVTGeom(geometry, !bbox!,4096,0,true) IS NOT NULL) AS tile"
         queries.append(base_query.replace("!bbox!","$1").replace("!scale_denominator!","$2").replace("!pixel_width!","$3").replace("!pixel_height!","$4"))
-    prepared = prepared + " UNION ALL ".join(queries) + ";"
-    print(prepared)
-    return(prepared)
+    function = function + " UNION ALL ".join(queries) + ";$$ LANGUAGE SQL"
+    print(function)
+    return(function)
 
-layers = GetTM2Source("/mapping/data.yml")
-prepared = GeneratePrepared(layers)
-engine = create_engine('postgresql://'+os.getenv('POSTGRES_USER','openmaptiles')+':'+os.getenv('POSTGRES_PASSWORD','openmaptiles')+'@'+os.getenv('POSTGRES_HOST','postgres')+':'+os.getenv('POSTGRES_PORT','5432')+'/'+os.getenv('POSTGRES_DB','openmaptiles'))
-inspector = inspect(engine)
-DBSession = sessionmaker(bind=engine)
-session = DBSession()
-session.execute(prepared)
+dsn = 'postgresql://'+os.getenv('POSTGRES_USER','openmaptiles')+':'+os.getenv('POSTGRES_PASSWORD','openmaptiles')+'@'+os.getenv('POSTGRES_HOST','postgres')+':'+os.getenv('POSTGRES_PORT','5432')+'/'+os.getenv('POSTGRES_DB','openmaptiles')
 
 def bounds(zoom,x,y):
     inProj = pyproj.Proj(init='epsg:4326')
@@ -62,7 +53,7 @@ def zoom_to_scale_denom(zoom):						# For !scale_denominator!
 def replace_tokens(query,s,w,n,e,scale_denom):
     return query.replace("!bbox!","ST_MakeBox2D(ST_Point("+w+", "+s+"), ST_Point("+e+", "+n+"))").replace("!scale_denominator!",scale_denom).replace("!pixel_width!","256").replace("!pixel_height!","256")
 
-def get_mvt(zoom,x,y):
+async def get_mvt(connection,zoom,x,y):
     try:								# Sanitize the inputs
         sani_zoom,sani_x,sani_y = float(zoom),float(x),float(y)
         del zoom,x,y
@@ -73,30 +64,45 @@ def get_mvt(zoom,x,y):
     scale_denom = zoom_to_scale_denom(sani_zoom)
     tilebounds = bounds(sani_zoom,sani_x,sani_y)
     s,w,n,e = str(tilebounds['s']),str(tilebounds['w']),str(tilebounds['n']),str(tilebounds['e'])
-    final_query = "EXECUTE gettile(!bbox!, !scale_denominator!, !pixel_width!, !pixel_height!);"
+    final_query = "SELECT gettile(!bbox!, !scale_denominator!, !pixel_width!, !pixel_height!);"
     sent_query = replace_tokens(final_query,s,w,n,e,scale_denom)
-    response = list(session.execute(sent_query))
-    print(sent_query)
+    log.info(sent_query)
+    response = await connection.fetch(sent_query)
     layers = filter(None,list(itertools.chain.from_iterable(response)))
     final_tile = b''
     for layer in layers:
-        final_tile = final_tile + io.BytesIO(layer).getvalue() 
+        final_tile = final_tile + io.BytesIO(layer).getvalue()
     return final_tile
 
 class GetTile(tornado.web.RequestHandler):
-    def get(self, zoom,x,y):
+    def initialize(self, pool):
+        self.pool = pool
+
+    async def get(self, zoom,x,y):
         self.set_header("Content-Type", "application/x-protobuf")
         self.set_header("Content-Disposition", "attachment")
         self.set_header("Access-Control-Allow-Origin", "*")
-        response = get_mvt(zoom,x,y)
-        self.write(response)
+        async with self.pool.acquire() as connection:
+                response = await get_mvt(connection, zoom,x,y)
+                self.write(response)
+
+async def get_pool():
+    pool = await asyncpg.create_pool(dsn = dsn)
+    layers = GetTM2Source(os.getenv("MAPPING_FILE", "/mapping/data.yml"))
+    # Make this prepared statement from the tm2source
+    create_function = GenerateFunction(layers)
+    async with pool.acquire() as connection:
+        await connection.execute(create_function)
+    return pool
 
 def m():
-    if __name__ == "__main__":
-        # Make this prepared statement from the tm2source
-        application = tornado.web.Application([(r"/tiles/([0-9]+)/([0-9]+)/([0-9]+).pbf", GetTile)])
+        enable_pretty_logging()
+        io_loop = tornado.ioloop.IOLoop.current()
+        pool = io_loop.run_sync(get_pool)
+        application = tornado.web.Application([(r"/tiles/([0-9]+)/([0-9]+)/([0-9]+).pbf", GetTile, dict(pool=pool))])
         print("Postserve started..")
-        application.listen(8080)
-        tornado.ioloop.IOLoop.instance().start()
+        application.listen(int(os.getenv("LISTEN_PORT", "8080")))
+        io_loop.start()
 
-m()
+if __name__ == "__main__":
+    m()