Fix issue where only one process caused a 1 second delay with concurrent GetMap requests (#24)

Author: geographika

docker/runtime/usr/local/bin/start-server

@@ -4,7 +4,8 @@ echo "Starting with apache2"
 
 # save the environment to be able to restore it in the FCGI daemon (used
 # in /usr/local/bin/qgis_mapsev_wrapper) for the startup code.
-${GET_ENV} | sed -e 's/^\([^=]*\)=.*/PassEnv \1/' > /tmp/pass-env
+# hide any PassEnv variable _ was undefined warnings
+${GET_ENV} | grep -v '^_=' | sed -e 's/^\([^=]*\)=.*/PassEnv \1/' > /tmp/pass-env
 
 # Save the environment to be able to restore it in the FCGI daemon (used in /usr/local/bin/mapserv_wrapper)
 ${GET_ENV} | sed -e 's/.\+/export "\0"/' > /tmp/init_env

workshop/exercises/docker-compose.yml

@@ -2,7 +2,7 @@
 #
 # Authors: Seth Girvin <sethg@geoggraphika.co.uk>
 #
-# Copyright (c) 2024 Seth Girvin
+# Copyright (c) 2026 Seth Girvin
 #
 # Permission is hereby granted, free of charge, to any person
 # obtaining a copy of this software and associated documentation
@@ -35,6 +35,9 @@ services:
       - 7000:8080
     environment:
       MAPSERVER_CONFIG_FILE: "/etc/mapserver/mapserver.conf"
+      MIN_PROCESSES: 2
+      IDLE_TIMEOUT: 3600 # 1 hour
+    command: ["bash", "/scripts/start-with-warmup.sh"]
     volumes:
       - ./scripts:/scripts:z
       - ./mapfiles:/etc/mapserver:z
@@ -49,6 +52,8 @@ services:
     working_dir: /home/node/app
     volumes:
       - ./app:/home/node/app:z
+      # Used for the GeoStyler demo
+      - ./mapfiles/includes:/home/node/app/public/includes:ro,z-
     networks:
       - mynetwork
     command: >

workshop/exercises/scripts/start-with-warmup.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+# Start MapServer with several FastCGI processes already running.
+#
+# mod_fcgid only starts a new MapServer process without delay when none
+# is busy. Otherwise a request waits 1 second for a busy process to
+# become free, so short concurrent requests (e.g. GetStyles + GetMap)
+# are slow. Sending MIN_PROCESSES requests at once, right after start-up,
+# starts that many processes; FcgidMinProcessesPerClass keeps them alive.
+(
+    sleep 3
+    for _ in $(seq "${MIN_PROCESSES:-2}"); do
+        (
+            exec 3<>/dev/tcp/127.0.0.1/8080 \
+                && printf 'GET / HTTP/1.0\r\nHost: localhost\r\n\r\n' >&3 \
+                && cat <&3 >/dev/null
+        ) &
+    done
+    wait
+) &
+
+# Continue with the image's normal start-up (Apache becomes PID 1)
+exec /usr/local/bin/start-server