Make pithos backend pool size configurable

Refs: #3561

snf-pithos-app/README

@@ -44,6 +44,7 @@ PITHOS_BACKEND_QUEUE_EXCHANGE    pithos
 PITHOS_BACKEND_QUOTA             50 GB (50 * 1024 ** 3)                                             Default user quota
 PITHOS_BACKEND_VERSIONING        auto                                                               Default versioning policy for containers
 PITHOS_BACKEND_FREE_VERSIONING   True                                                               Default versioning debit policy (default free)
+PITHOS_BACKEND_POOL_SIZE         5                                                                  Default backend pool size
 PITHOS_UPDATE_MD5                True                                                               Update object checksums when using hashmaps
 PITHOS_SERVICE_TOKEN             ''                                                                 Service token acquired by the identity provider (astakos)
 PITHOS_RADOS_STORAGE             False                                                              Enables or disables secondary Pithos storage on RADOS

snf-pithos-app/conf/20-snf-pithos-app-settings.conf

@@ -63,3 +63,5 @@
 # Higher values mean more safety and longer URLs
 #
 #PITHOS_PUBLIC_URL_SECURITY = 16
+#
+#PITHOS_BACKEND_POOL_SIZE = 5

snf-pithos-app/pithos/api/settings.py

@@ -32,6 +32,9 @@ BACKEND_QUOTA = getattr(
 BACKEND_VERSIONING = getattr(settings, 'PITHOS_BACKEND_VERSIONING', 'auto')
 BACKEND_FREE_VERSIONING = getattr(settings, 'PITHOS_BACKEND_FREE_VERSIONING', True)
 
+# Default backend pool size
+BACKEND_POOL_SIZE = getattr(settings, 'PITHOS_BACKEND_POOL_SIZE', 5)
+
 # Update object checksums when using hashmaps.
 UPDATE_MD5 = getattr(settings, 'PITHOS_UPDATE_MD5', True)
 

snf-pithos-app/pithos/api/util.py

@@ -63,7 +63,7 @@ from pithos.api.settings import (BACKEND_DB_MODULE, BACKEND_DB_CONNECTION,
                                  QUOTAHOLDER_URL, QUOTAHOLDER_TOKEN,
                                  QUOTAHOLDER_POOLSIZE,
                                  BACKEND_QUOTA, BACKEND_VERSIONING,
-                                 BACKEND_FREE_VERSIONING,
+                                 BACKEND_FREE_VERSIONING, BACKEND_POOL_SIZE,
                                  AUTHENTICATION_URL, AUTHENTICATION_USERS,
                                  COOKIE_NAME, USER_CATALOG_URL,
                                  RADOS_STORAGE, RADOS_POOL_BLOCKS,
@@ -958,7 +958,7 @@ def simple_list_response(request, l):
 
 
 from pithos.backends.util import PithosBackendPool
-POOL_SIZE = 5
+
 if RADOS_STORAGE:
     BLOCK_PARAMS = { 'mappool': RADOS_POOL_MAPS,
                      'blockpool': RADOS_POOL_BLOCKS,
@@ -970,7 +970,7 @@ else:
 
 
 _pithos_backend_pool = PithosBackendPool(
-        size=POOL_SIZE,
+        size=BACKEND_POOL_SIZE,
         db_module=BACKEND_DB_MODULE,
         db_connection=BACKEND_DB_CONNECTION,
         block_module=BACKEND_BLOCK_MODULE,