Elastic: paralellise reindexing

It's marginally faster (on our production DB user reindexing goes down from
5+ minutes to 4 minutes), but will likely become significantly faster when
we run ElasticSearch on its own machine.

pillar/__init__.py

@@ -866,3 +866,11 @@ class PillarServer(BlinkerCompatibleEve):
     @property
     def user_caps(self) -> typing.Mapping[str, typing.FrozenSet[str]]:
         return self._user_caps
+
+    @property
+    def real_app(self) -> 'PillarServer':
+        """The real application object.
+
+        Can be used to obtain the real app object from a LocalProxy.
+        """
+        return self

pillar/cli/elastic.py

@@ -1,7 +1,8 @@
+import concurrent.futures
 import logging
 import typing
-import bson
 
+import bson
 from flask_script import Manager
 
 from pillar import current_app
@@ -16,6 +17,7 @@ name_to_task = {
     'nodes': index.ResetNodeIndex,
     'users': index.ResetUserIndex,
 }
+REINDEX_THREAD_COUNT = 3
 
 
 @manager_elastic.option('indices', nargs='*')
@@ -47,27 +49,41 @@ def _reindex_users():
     # in prepare_user_data(…)
     users = users_coll.find()
     user_count = users.count()
+    indexed = 0
 
     log.info('Reindexing %d users in Elastic', user_count)
 
     from pillar.celery.search_index_tasks import prepare_user_data
     from pillar.api.search import elastic_indexing
 
-    indexed = 0
-    for idx, user in enumerate(users):
-        if idx % 100 == 0:
-            log.info('Processing user %d/%d', idx+1, user_count)
-        to_index = prepare_user_data('', user=user)
-        if not to_index:
-            log.debug('missing user..')
-            continue
+    app = current_app.real_app
 
-        try:
-            elastic_indexing.push_updated_user(to_index)
-        except(KeyError, AttributeError):
-            log.exception('Field is missing for %s', user)
-        else:
-            indexed += 1
+    def do_work(work_idx_user):
+        nonlocal indexed
+        idx, user = work_idx_user
+
+        with app.app_context():
+            if idx % 100 == 0:
+                log.info('Processing user %d/%d', idx+1, user_count)
+            to_index = prepare_user_data('', user=user)
+            if not to_index:
+                log.debug('not indexing user %s', user)
+                return
+
+            try:
+                elastic_indexing.push_updated_user(to_index)
+            except(KeyError, AttributeError):
+                log.exception('Field is missing for %s', user)
+            else:
+                indexed += 1
+
+    with concurrent.futures.ThreadPoolExecutor(max_workers=REINDEX_THREAD_COUNT) as executor:
+        result = executor.map(do_work, enumerate(users))
+
+        # When an exception occurs, it's enough to just iterate over the results.
+        # That will re-raise the exception in the main thread.
+        for ob in result:
+            log.debug('result: %s', ob)
     log.info('Reindexed %d/%d users', indexed, user_count)
 
 
@@ -90,23 +106,35 @@ def _reindex_nodes():
         '_deleted': {'$ne': True},
     })
     node_count = nodes.count()
+    indexed = 0
 
     log.info('Nodes %d will be reindexed in Elastic', node_count)
+    app = current_app.real_app
 
     from pillar.celery.search_index_tasks import prepare_node_data
     from pillar.api.search import elastic_indexing
 
-    indexed = 0
-    for idx, node in enumerate(nodes):
-        if idx % 100 == 0:
-            log.info('Processing node %d/%d', idx+1, node_count)
-        try:
-            to_index = prepare_node_data('', node=node)
-            elastic_indexing.index_node_save(to_index)
-        except (KeyError, AttributeError):
-            log.exception('Node %s is missing Field', node)
-        else:
-            indexed += 1
+    def do_work(work_idx_node):
+        nonlocal indexed
+
+        idx, node = work_idx_node
+        with app.app_context():
+            if idx % 100 == 0:
+                log.info('Processing node %d/%d', idx+1, node_count)
+            try:
+                to_index = prepare_node_data('', node=node)
+                elastic_indexing.index_node_save(to_index)
+            except (KeyError, AttributeError):
+                log.exception('Node %s is missing a field', node)
+            else:
+                indexed += 1
+
+    with concurrent.futures.ThreadPoolExecutor(max_workers=REINDEX_THREAD_COUNT) as executor:
+        result = executor.map(do_work, enumerate(nodes))
+        # When an exception occurs, it's enough to just iterate over the results.
+        # That will re-raise the exception in the main thread.
+        for ob in result:
+            log.debug('result: %s', ob)
     log.info('Reindexed %d/%d nodes', indexed, node_count)