diff --git a/Annex/Branch/Transitions.hs b/Annex/Branch/Transitions.hs
index f3b1e3fd0c..0841226f53 100644
--- a/Annex/Branch/Transitions.hs
+++ b/Annex/Branch/Transitions.hs
@@ -24,6 +24,7 @@ import Types.MetaData
 import qualified Data.Map as M
 import qualified Data.Set as S
 import qualified Data.ByteString.Lazy as L
+import qualified Data.Attoparsec.ByteString.Lazy as A
 import Data.ByteString.Builder
 
 data FileTransition
@@ -48,11 +49,11 @@ dropDead f content trustmap = case getLogVariety f of
 			UUIDBased.buildLog (byteString . encodeBS) $
 				dropDeadFromMapLog trustmap id $ UUIDBased.parseLog Just (decodeBL content)
 	Just NewUUIDBasedLog -> ChangeFile $
-		UUIDBased.buildLogNew (byteString . encodeBS) $
+		UUIDBased.buildLogNew byteString $
 			dropDeadFromMapLog trustmap id $
-				UUIDBased.parseLogNew Just (decodeBL content)
+				UUIDBased.parseLogNew A.takeByteString content
 	Just (ChunkLog _) -> ChangeFile $
-		Chunk.buildLog $ dropDeadFromMapLog trustmap fst $ Chunk.parseLog (decodeBL content)
+		Chunk.buildLog $ dropDeadFromMapLog trustmap fst $ Chunk.parseLog content
 	Just (PresenceLog _) ->
 		let newlog = Presence.compactLog $ dropDeadFromPresenceLog trustmap $ Presence.parseLog content
 		in if null newlog
diff --git a/Logs/Chunk.hs b/Logs/Chunk.hs
index 11b49b6209..cbcb747bd4 100644
--- a/Logs/Chunk.hs
+++ b/Logs/Chunk.hs
@@ -38,7 +38,7 @@ chunksStored u k chunkmethod chunkcount = do
 	c <- liftIO currentVectorClock
 	config <- Annex.getGitConfig
 	Annex.Branch.change (chunkLogFile config k) $
-		buildLog . changeMapLog c (u, chunkmethod) chunkcount . parseLog . decodeBL
+		buildLog . changeMapLog c (u, chunkmethod) chunkcount . parseLog
 
 chunksRemoved :: UUID -> Key -> ChunkMethod -> Annex ()
 chunksRemoved u k chunkmethod = chunksStored u k chunkmethod 0
@@ -46,7 +46,7 @@ chunksRemoved u k chunkmethod = chunksStored u k chunkmethod 0
 getCurrentChunks :: UUID -> Key -> Annex [(ChunkMethod, ChunkCount)]
 getCurrentChunks u k = do
 	config <- Annex.getGitConfig
-	select . parseLog . decodeBL <$> Annex.Branch.get (chunkLogFile config k)
+	select . parseLog <$> Annex.Branch.get (chunkLogFile config k)
   where
 	select = filter (\(_m, ct) -> ct > 0)
 		. map (\((_ku, m), l) -> (m, value l))
diff --git a/Logs/Chunk/Pure.hs b/Logs/Chunk/Pure.hs
index fa3788ca8d..73e27b5c91 100644
--- a/Logs/Chunk/Pure.hs
+++ b/Logs/Chunk/Pure.hs
@@ -19,6 +19,9 @@ import Logs.MapLog
 import Data.Int
 
 import qualified Data.ByteString as S
+import qualified Data.ByteString.Lazy as L
+import qualified Data.Attoparsec.ByteString.Lazy as A
+import qualified Data.Attoparsec.ByteString.Char8 as A8
 import Data.ByteString.Builder
 
 -- Currently chunks are all fixed size, but other chunking methods
@@ -33,20 +36,13 @@ type ChunkCount = Integer
 
 type ChunkLog = MapLog (UUID, ChunkMethod) ChunkCount
 
-parseChunkMethod :: String -> ChunkMethod
-parseChunkMethod s = maybe (UnknownChunks $ encodeBS s) FixedSizeChunks (readish s)
-
 buildChunkMethod :: ChunkMethod -> Builder
 buildChunkMethod (FixedSizeChunks sz) = int64Dec sz
 buildChunkMethod (UnknownChunks s) = byteString s
 
-parseLog :: String -> ChunkLog
-parseLog = parseMapLog fieldparser valueparser
-  where
-	fieldparser s =
-		let (u,m) = separate (== ':') s
-		in Just (toUUID u, parseChunkMethod m)
-	valueparser = readish
+chunkMethodParser :: A.Parser ChunkMethod
+chunkMethodParser =
+	(FixedSizeChunks <$> A8.decimal) <|> (UnknownChunks <$> A.takeByteString)
 
 buildLog :: ChunkLog -> Builder
 buildLog = buildMapLog fieldbuilder valuebuilder
@@ -54,3 +50,13 @@ buildLog = buildMapLog fieldbuilder valuebuilder
 	fieldbuilder (u, m) = buildUUID u <> sep <> buildChunkMethod m
 	valuebuilder = integerDec
 	sep = charUtf8 ':'
+
+parseLog :: L.ByteString -> ChunkLog
+parseLog = parseMapLog fieldparser valueparser
+  where
+	fieldparser = (,)
+		<$> (toUUID <$> A8.takeTill (== ':'))
+		<* A8.char ':'
+		<*> chunkMethodParser
+		<* A.endOfInput
+	valueparser = A8.decimal
diff --git a/Logs/Config.hs b/Logs/Config.hs
index 767cee48ac..8773c432ae 100644
--- a/Logs/Config.hs
+++ b/Logs/Config.hs
@@ -20,6 +20,8 @@ import Logs.MapLog
 import qualified Annex.Branch
 
 import qualified Data.Map as M
+import qualified Data.ByteString.Lazy as L
+import qualified Data.Attoparsec.ByteString.Lazy as A
 import Data.ByteString.Builder
 
 type ConfigName = String
@@ -35,7 +37,7 @@ setGlobalConfig' :: ConfigName -> ConfigValue -> Annex ()
 setGlobalConfig' name new = do
 	c <- liftIO currentVectorClock
 	Annex.Branch.change configLog $ 
-		buildGlobalConfig . changeMapLog c name new . parseGlobalConfig . decodeBL
+		buildGlobalConfig . changeMapLog c name new . parseGlobalConfig
 
 unsetGlobalConfig :: ConfigName -> Annex ()
 unsetGlobalConfig name = do
@@ -53,9 +55,11 @@ buildGlobalConfig = buildMapLog fieldbuilder valuebuilder
 	fieldbuilder = byteString . encodeBS
 	valuebuilder = byteString . encodeBS
 
-parseGlobalConfig :: String -> MapLog ConfigName ConfigValue
-parseGlobalConfig = parseMapLog Just Just
+parseGlobalConfig :: L.ByteString -> MapLog ConfigName ConfigValue
+parseGlobalConfig = parseMapLog string string
+  where
+	string = decodeBS <$> A.takeByteString
 
 loadGlobalConfig :: Annex (M.Map ConfigName ConfigValue)
-loadGlobalConfig = M.filter (not . null) . simpleMap . parseGlobalConfig . decodeBL
+loadGlobalConfig = M.filter (not . null) . simpleMap . parseGlobalConfig
 	<$> Annex.Branch.get configLog
diff --git a/Logs/Export.hs b/Logs/Export.hs
index ac0208bcf5..57fa0f565f 100644
--- a/Logs/Export.hs
+++ b/Logs/Export.hs
@@ -18,6 +18,9 @@ import Logs
 import Logs.MapLog
 import Annex.UUID
 
+import qualified Data.ByteString.Lazy as L
+import qualified Data.Attoparsec.ByteString.Lazy as A
+import qualified Data.Attoparsec.ByteString.Char8 as A8
 import Data.ByteString.Builder
 
 data Exported = Exported
@@ -30,7 +33,7 @@ data ExportParticipants = ExportParticipants
 	{ exportFrom :: UUID
 	, exportTo :: UUID
 	}
-	deriving (Eq, Ord)
+	deriving (Eq, Ord, Show)
 
 data ExportChange = ExportChange
 	{ oldTreeish :: [Git.Ref]
@@ -44,7 +47,6 @@ data ExportChange = ExportChange
 getExport :: UUID -> Annex [Exported]
 getExport remoteuuid = nub . mapMaybe get . M.toList . simpleMap 
 	. parseExportLog
-	. decodeBL
 	<$> Annex.Branch.get exportLog
   where
 	get (ep, exported)
@@ -74,7 +76,7 @@ recordExport remoteuuid ec = do
 		buildExportLog
 			. changeMapLog c ep exported 
 			. M.mapWithKey (updateothers c u)
-			. parseExportLog . decodeBL
+			. parseExportLog
   where
 	updateothers c u ep le@(LogEntry _ exported@(Exported { exportedTreeish = t }))
 		| u == exportFrom ep || remoteuuid /= exportTo ep || t `notElem` oldTreeish ec = le
@@ -92,17 +94,16 @@ recordExportBeginning remoteuuid newtree = do
 	old <- fromMaybe (Exported emptyTree [])
 		. M.lookup ep . simpleMap 
 		. parseExportLog
-		. decodeBL
 		<$> Annex.Branch.get exportLog
 	let new = old { incompleteExportedTreeish = nub (newtree:incompleteExportedTreeish old) }
 	Annex.Branch.change exportLog $
 		buildExportLog 
 			. changeMapLog c ep new
-			. parseExportLog . decodeBL
+			. parseExportLog
 	Annex.Branch.graftTreeish newtree (asTopFilePath "export.tree")
 
-parseExportLog :: String -> MapLog ExportParticipants Exported
-parseExportLog = parseMapLog parseExportParticipants parseExported
+parseExportLog :: L.ByteString -> MapLog ExportParticipants Exported
+parseExportLog = parseMapLog exportParticipantsParser exportedParser
 
 buildExportLog :: MapLog ExportParticipants Exported -> Builder
 buildExportLog = buildMapLog buildExportParticipants buildExported
@@ -113,14 +114,11 @@ buildExportParticipants ep =
   where
 	sep = charUtf8 ':'
 
-parseExportParticipants :: String -> Maybe ExportParticipants
-parseExportParticipants s = case separate (== ':') s of
-	("",_) -> Nothing
-	(_,"") -> Nothing
-	(f,t) -> Just $ ExportParticipants
-		{ exportFrom = toUUID f
-		, exportTo = toUUID t
-		}
+exportParticipantsParser :: A.Parser ExportParticipants
+exportParticipantsParser = ExportParticipants
+	<$> (toUUID <$> A8.takeWhile1 (/= ':'))
+	<* A8.char ':'
+	<*> (toUUID <$> A8.takeWhile1 (const True))
 
 buildExported :: Exported -> Builder
 buildExported exported = go (exportedTreeish exported : incompleteExportedTreeish exported)
@@ -129,7 +127,8 @@ buildExported exported = go (exportedTreeish exported : incompleteExportedTreeis
 	go (r:rs) = rref r <> mconcat [ charUtf8 ' ' <> rref r' | r' <- rs ]
 	rref r = byteString (encodeBS' (Git.fromRef r))
 
-parseExported :: String -> Maybe Exported
-parseExported s = case words s of
-	(et:it) -> Just $ Exported (Git.Ref et) (map Git.Ref it)
-	_ -> Nothing
+exportedParser :: A.Parser Exported
+exportedParser = Exported <$> refparser <*> many refparser
+  where
+	refparser = (Git.Ref . decodeBS <$> A8.takeWhile1 (/= ' ') )
+		<* ((const () <$> A8.char ' ') <|> A.endOfInput)
diff --git a/Logs/MapLog.hs b/Logs/MapLog.hs
index c0018f79b7..72307b2fb0 100644
--- a/Logs/MapLog.hs
+++ b/Logs/MapLog.hs
@@ -4,6 +4,8 @@
  -
  - A line of the log will look like: "timestamp field value"
  -
+ - The field names cannot contain whitespace.
+ -
  - Copyright 2014, 2019 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU GPL version 3 or higher.
@@ -19,13 +21,16 @@ import Common
 import Annex.VectorClock
 import Logs.Line
 
+import qualified Data.ByteString.Lazy as L
 import qualified Data.Map.Strict as M
+import qualified Data.Attoparsec.ByteString.Lazy as A
+import qualified Data.Attoparsec.ByteString.Char8 as A8
 import Data.ByteString.Builder
 
 data LogEntry v = LogEntry
 	{ changed :: VectorClock
 	, value :: v
-	} deriving (Eq)
+	} deriving (Eq, Show)
 
 type MapLog f v = M.Map f (LogEntry v)
 
@@ -39,17 +44,23 @@ buildMapLog fieldbuilder valuebuilder = mconcat . map genline . M.toList
 	sp = charUtf8 ' '
 	nl = charUtf8 '\n'
 
-parseMapLog :: Ord f => (String -> Maybe f) -> (String -> Maybe v) -> String -> MapLog f v
-parseMapLog fieldparser valueparser = M.fromListWith best . mapMaybe parse . splitLines
+parseMapLog :: Ord f => A.Parser f -> A.Parser v -> L.ByteString -> MapLog f v
+parseMapLog fieldparser valueparser = fromMaybe M.empty . A.maybeResult 
+	. A.parse (mapLogParser fieldparser valueparser)
+
+mapLogParser :: Ord f => A.Parser f -> A.Parser v -> A.Parser (MapLog f v)
+mapLogParser fieldparser valueparser = M.fromListWith best <$> parseLogLines go
   where
-	parse line = do
-		let (sc, rest) = splitword line
-		    (sf, sv) = splitword rest
-		c <- parseVectorClock sc
-		f <- fieldparser sf
-		v <- valueparser sv
-		Just (f, LogEntry c v)
-	splitword = separate (== ' ')
+	go = do
+		c <- vectorClockParser
+		_ <- A8.char ' '
+		w <- A8.takeTill (== ' ')
+		f <- either fail return $
+			A.parseOnly (fieldparser <* A.endOfInput) w
+		_ <- A8.char ' '
+		v <- valueparser
+		A.endOfInput
+		return (f, LogEntry c v)
 
 changeMapLog :: Ord f => VectorClock -> f -> v -> MapLog f v -> MapLog f v
 changeMapLog c f v = M.insert f $ LogEntry c v
diff --git a/Logs/PreferredContent/Raw.hs b/Logs/PreferredContent/Raw.hs
index b095428461..2d572f9dcc 100644
--- a/Logs/PreferredContent/Raw.hs
+++ b/Logs/PreferredContent/Raw.hs
@@ -18,6 +18,7 @@ import Types.Group
 
 import qualified Data.Map as M
 import qualified Data.ByteString.Lazy as L
+import qualified Data.Attoparsec.ByteString.Lazy as A
 import Data.ByteString.Builder
 
 {- Changes the preferred content configuration of a remote. -}
@@ -51,7 +52,10 @@ groupPreferredContentSet g val = do
 	Annex.changeState $ \s -> s { Annex.preferredcontentmap = Nothing }
 
 parseGroupPreferredContent :: L.ByteString -> MapLog Group String
-parseGroupPreferredContent = parseMapLog (Just . toGroup) Just . decodeBL
+parseGroupPreferredContent = parseMapLog parsegroup parsestring
+  where
+	parsegroup = Group <$> A.takeByteString
+	parsestring = decodeBS <$> A.takeByteString
 
 buildGroupPreferredContent :: MapLog Group PreferredContentExpression -> Builder
 buildGroupPreferredContent = buildMapLog buildgroup buildexpr
diff --git a/Logs/RemoteState.hs b/Logs/RemoteState.hs
index 5b856b713c..ec3f5ae392 100644
--- a/Logs/RemoteState.hs
+++ b/Logs/RemoteState.hs
@@ -17,6 +17,8 @@ import qualified Annex.Branch
 import qualified Annex
 
 import qualified Data.Map as M
+import qualified Data.ByteString.Lazy as L
+import qualified Data.Attoparsec.ByteString.Lazy as A
 import Data.ByteString.Builder
 
 type RemoteState = String
@@ -26,7 +28,7 @@ setRemoteState u k s = do
 	c <- liftIO currentVectorClock
 	config <- Annex.getGitConfig
 	Annex.Branch.change (remoteStateLogFile config k) $
-		buildRemoteState . changeLog c u s . parseLogNew Just . decodeBL
+		buildRemoteState . changeLog c u s . parseRemoteState
 
 buildRemoteState :: Log RemoteState -> Builder
 buildRemoteState = buildLogNew (byteString . encodeBS)
@@ -34,7 +36,10 @@ buildRemoteState = buildLogNew (byteString . encodeBS)
 getRemoteState :: UUID -> Key -> Annex (Maybe RemoteState)
 getRemoteState u k = do
 	config <- Annex.getGitConfig
-	extract . parseLogNew Just . decodeBL
+	extract . parseRemoteState
 		<$> Annex.Branch.get (remoteStateLogFile config k)
   where
 	extract m = value <$> M.lookup u m
+
+parseRemoteState :: L.ByteString -> Log RemoteState
+parseRemoteState = parseLogNew (decodeBS <$> A.takeByteString)
diff --git a/Logs/Schedule.hs b/Logs/Schedule.hs
index b8eb94f8b1..e43af52a85 100644
--- a/Logs/Schedule.hs
+++ b/Logs/Schedule.hs
@@ -42,10 +42,10 @@ scheduleSet NoUUID _ = error "unknown UUID; cannot modify"
 
 scheduleMap :: Annex (M.Map UUID [ScheduledActivity])
 scheduleMap = simpleMap
-	. parseLogWithUUID parser . decodeBL
+	. parseLog parser . decodeBL
 	<$> Annex.Branch.get scheduleLog
   where
-	parser _uuid = eitherToMaybe . parseScheduledActivities
+	parser = eitherToMaybe . parseScheduledActivities
 
 scheduleGet :: UUID -> Annex (S.Set ScheduledActivity)
 scheduleGet u = do
diff --git a/Logs/UUIDBased.hs b/Logs/UUIDBased.hs
index e371844921..f8bd1f7253 100644
--- a/Logs/UUIDBased.hs
+++ b/Logs/UUIDBased.hs
@@ -39,6 +39,8 @@ import Annex.VectorClock
 import Logs.MapLog
 import Logs.Line
 
+import qualified Data.ByteString.Lazy as L
+import qualified Data.Attoparsec.ByteString.Lazy as A
 import Data.ByteString.Builder
 
 type Log v = MapLog UUID v
@@ -84,8 +86,8 @@ parseLogWithUUID parser = M.fromListWith best . mapMaybe parse . splitLines
 buildLogNew :: (v -> Builder) -> Log v -> Builder
 buildLogNew = buildMapLog buildUUID
 
-parseLogNew :: (String -> Maybe v) -> String -> Log v
-parseLogNew = parseMapLog (Just . toUUID)
+parseLogNew :: A.Parser v -> L.ByteString -> Log v
+parseLogNew = parseMapLog (toUUID <$> A.takeByteString)
 
 changeLog :: VectorClock -> UUID -> v -> Log v -> Log v
 changeLog = changeMapLog