properly close connections of indexer after use

nominatim/indexer/indexer.py

@@ -124,8 +124,25 @@ class Indexer:
     """
 
     def __init__(self, dsn, num_threads):
-        self.conn = psycopg2.connect(dsn)
-        self.threads = [DBConnection(dsn) for _ in range(num_threads)]
+        self.dsn = dsn
+        self.num_threads = num_threads
+        self.conn = None
+        self.threads = []
+
+
+    def _setup_connections(self):
+        self.conn = psycopg2.connect(self.dsn)
+        self.threads = [DBConnection(self.dsn) for _ in range(self.num_threads)]
+
+
+    def _close_connections(self):
+        if self.conn:
+            self.conn.close()
+            self.conn = None
+
+        for thread in self.threads:
+            thread.close()
+        threads = []
 
 
     def index_full(self, analyse=True):
@@ -134,34 +151,44 @@ class Indexer:
             database will be analysed at the appropriate places to
             ensure that database statistics are updated.
         """
-        self.index_by_rank(0, 4)
-        self._analyse_db_if(analyse)
+        conn = psycopg2.connect(self.dsn)
 
-        self.index_boundaries(0, 30)
-        self._analyse_db_if(analyse)
+        try:
+            self.index_by_rank(0, 4)
+            self._analyse_db_if(conn, analyse)
 
-        self.index_by_rank(5, 25)
-        self._analyse_db_if(analyse)
+            self.index_boundaries(0, 30)
+            self._analyse_db_if(conn, analyse)
 
-        self.index_by_rank(26, 30)
-        self._analyse_db_if(analyse)
+            self.index_by_rank(5, 25)
+            self._analyse_db_if(conn, analyse)
 
-        self.index_postcodes()
-        self._analyse_db_if(analyse)
+            self.index_by_rank(26, 30)
+            self._analyse_db_if(conn, analyse)
 
-    def _analyse_db_if(self, condition):
+            self.index_postcodes()
+            self._analyse_db_if(conn, analyse)
+        finally:
+            conn.close()
+
+    def _analyse_db_if(self, conn, condition):
         if condition:
-            with self.conn.cursor() as cur:
+            with conn.cursor() as cur:
                 cur.execute('ANALYSE')
 
     def index_boundaries(self, minrank, maxrank):
         """ Index only administrative boundaries within the given rank range.
         """
         LOG.warning("Starting indexing boundaries using %s threads",
-                    len(self.threads))
+                    self.num_threads)
 
-        for rank in range(max(minrank, 4), min(maxrank, 26)):
-            self.index(BoundaryRunner(rank))
+        self._setup_connections()
+
+        try:
+            for rank in range(max(minrank, 4), min(maxrank, 26)):
+                self.index(BoundaryRunner(rank))
+        finally:
+            self._close_connections()
 
     def index_by_rank(self, minrank, maxrank):
         """ Index all entries of placex in the given rank range (inclusive)
@@ -172,30 +199,48 @@ class Indexer:
         """
         maxrank = min(maxrank, 30)
         LOG.warning("Starting indexing rank (%i to %i) using %i threads",
-                    minrank, maxrank, len(self.threads))
+                    minrank, maxrank, self.num_threads)
 
-        for rank in range(max(1, minrank), maxrank):
-            self.index(RankRunner(rank))
+        self._setup_connections()
 
-        if maxrank == 30:
-            self.index(RankRunner(0))
-            self.index(InterpolationRunner(), 20)
-            self.index(RankRunner(30), 20)
-        else:
-            self.index(RankRunner(maxrank))
+        try:
+            for rank in range(max(1, minrank), maxrank):
+                self.index(RankRunner(rank))
+
+            if maxrank == 30:
+                self.index(RankRunner(0))
+                self.index(InterpolationRunner(), 20)
+                self.index(RankRunner(30), 20)
+            else:
+                self.index(RankRunner(maxrank))
+        finally:
+            self._close_connections()
 
 
     def index_postcodes(self):
         """Index the entries ofthe location_postcode table.
         """
-        self.index(PostcodeRunner(), 20)
+        LOG.warning("Starting indexing postcodes using %s threads", self.num_threads)
+
+        self._setup_connections()
+
+        try:
+            self.index(PostcodeRunner(), 20)
+        finally:
+            self._close_connections()
 
     def update_status_table(self):
         """ Update the status in the status table to 'indexed'.
         """
-        with self.conn.cursor() as cur:
-            cur.execute('UPDATE import_status SET indexed = true')
-        self.conn.commit()
+        conn = psycopg2.connect(self.dsn)
+
+        try:
+            with conn.cursor() as cur:
+                cur.execute('UPDATE import_status SET indexed = true')
+
+            conn.commit()
+        finally:
+            conn.close()
 
     def index(self, obj, batch=1):
         """ Index a single rank or table. `obj` describes the SQL to use