From bd25f9cf36ff86d1616853d88cebd2a4a83fa552 Mon Sep 17 00:00:00 2001 From: Richard van der Hoff Date: Sat, 3 Feb 2018 23:05:41 +0000 Subject: [PATCH] Clean up work_mem handling Add some comments and improve exception handling when twiddling work_mem for the search update --- synapse/storage/search.py | 52 ++++++++++++++++++++++++++++++--------- 1 file changed, 41 insertions(+), 11 deletions(-) diff --git a/synapse/storage/search.py b/synapse/storage/search.py index 205e8d0017..190751bade 100644 --- a/synapse/storage/search.py +++ b/synapse/storage/search.py @@ -12,7 +12,7 @@ # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. - +import sys from twisted.internet import defer from .background_updates import BackgroundUpdateStore @@ -256,21 +256,51 @@ class SearchStore(BackgroundUpdateStore): value (str): """ if isinstance(self.database_engine, PostgresEngine): - txn.execute("SET work_mem='256kB'") sql = ( "INSERT INTO event_search" - " (event_id, room_id, key, vector, stream_ordering, origin_server_ts)" + " (event_id, room_id, key, vector, stream_ordering, " + " origin_server_ts)" " VALUES (?,?,?,to_tsvector('english', ?),?,?)" ) - txn.execute( - sql, - ( - event.event_id, event.room_id, key, value, - event.internal_metadata.stream_ordering, - event.origin_server_ts, + + # inserts to a GIN index are normally batched up into a pending + # list, and then all committed together once the list gets to a + # certain size. The trouble with that is that postgres (pre-9.5) + # uses work_mem to determine the length of the list, and work_mem + # is typically very large. + # + # We therefore reduce work_mem while we do the insert. + # + # (postgres 9.5 uses the separate gin_pending_list_limit setting, + # so doesn't suffer the same problem, but changing work_mem will + # be harmless) + + txn.execute("SET work_mem='256kB'") + try: + txn.execute( + sql, + ( + event.event_id, event.room_id, key, value, + event.internal_metadata.stream_ordering, + event.origin_server_ts, + ) ) - ) - txn.execute("RESET work_mem") + except Exception: + # we need to reset work_mem, but doing so may throw a new + # exception and we want to preserve the original + t, v, tb = sys.exc_info() + try: + txn.execute("RESET work_mem") + except Exception as e: + logger.warn( + "exception resetting work_mem during exception " + "handling: %r", + e, + ) + raise t, v, tb + else: + txn.execute("RESET work_mem") + elif isinstance(self.database_engine, Sqlite3Engine): sql = ( "INSERT INTO event_search (event_id, room_id, key, value)"