Allow global setting of compile process limit (#4081)

docker/ha-addon-rootfs/etc/services.d/esphome/run

@@ -22,6 +22,14 @@ if bashio::config.has_value 'relative_url'; then
     export ESPHOME_DASHBOARD_RELATIVE_URL=$(bashio::config 'relative_url')
 fi
 
+if bashio::config.has_value 'default_compile_process_limit'; then
+    export ESPHOME_DEFAULT_COMPILE_PROCESS_LIMIT=$(bashio::config 'default_compile_process_limit')
+else
+    if grep -q 'Raspberry Pi 3' /proc/cpuinfo; then
+        export ESPHOME_DEFAULT_COMPILE_PROCESS_LIMIT=1;
+    fi
+fi
+
 pio_cache_base=/data/cache/platformio
 # we can't set core_dir, because the settings file is stored in `core_dir/appstate.json`
 # setting `core_dir` would therefore prevent pio from accessing

esphome/core/config.py

@@ -110,6 +110,15 @@ def validate_version(value: str):
     return value
 
 
+if "ESPHOME_DEFAULT_COMPILE_PROCESS_LIMIT" in os.environ:
+    _compile_process_limit_default = min(
+        int(os.environ["ESPHOME_DEFAULT_COMPILE_PROCESS_LIMIT"]),
+        multiprocessing.cpu_count(),
+    )
+else:
+    _compile_process_limit_default = cv.UNDEFINED
+
+
 CONF_ESP8266_RESTORE_FROM_FLASH = "esp8266_restore_from_flash"
 CONFIG_SCHEMA = cv.All(
     cv.Schema(
@@ -153,9 +162,9 @@ CONFIG_SCHEMA = cv.All(
             cv.Optional(CONF_MIN_VERSION, default=ESPHOME_VERSION): cv.All(
                 cv.version_number, validate_version
             ),
-            cv.Optional(CONF_COMPILE_PROCESS_LIMIT): cv.int_range(
-                min=1, max=multiprocessing.cpu_count()
-            ),
+            cv.Optional(
+                CONF_COMPILE_PROCESS_LIMIT, default=_compile_process_limit_default
+            ): cv.int_range(min=1, max=multiprocessing.cpu_count()),
         }
     ),
     validate_hostname,