STRLCPY/graphql-engine

server: use lighter GC in ourIdleGC when idle

Previously when users had an idle system with a large working set (i.e. large schema) they would likely see CPU spikes every 10 seconds.

See: https://github.com/hasura/graphql-engine/issues/9592#issuecomment-1580543694

Now we perform a lighter-weight minor GC in that case.

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/9841
GitOrigin-RevId: 2a49a83c4b763546a901558641ab9b6460ebffd9

Brandon Simmons committed with hasura-bot 2 months ago

956a698f

1 parent d966e0a9

Total 1 files

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server/src-lib/Hasura/GC.hs

		skipped 6 lines
7	7		import GHC.Stats
8	8		import Hasura.Logging
9	9		import Hasura.Prelude
10		-	import System.Mem (performMajorGC)
	10	+	import System.Mem (performMajorGC, performMinorGC)
11	11
12	12		-- \| The RTS's idle GC doesn't work for us:
13	13		--
		skipped 20 lines
34	34		DiffTime ->
35	35		IO void
36	36		ourIdleGC (Logger logger) idleInterval minGCInterval maxNoGCInterval =
37		-	startTimer >>= go 0 0
	37	+	startTimer >>= go 0 0 False
38	38		where
39		-	go gcs_prev major_gcs_prev timerSinceLastMajorGC = do
	39	+	go gcs_prev major_gcs_prev lastIterationPerformedGC timerSinceLastMajorGC = do
40	40		timeSinceLastGC <- timerSinceLastMajorGC
41	41		when (timeSinceLastGC < minGCInterval) $ do
42	42		-- no need to check idle until we've passed the minGCInterval:
		skipped 6 lines
49	49		let areIdle = gcs == gcs_prev
50	50		areOverdue = timeSinceLastGC > maxNoGCInterval
51	51
52		-	-- a major GC was run since last iteration (cool!), reset timer:
53	52		if
54		-	\| major_gcs > major_gcs_prev -> do
55		-	startTimer >>= go gcs major_gcs
	53	+	-- a major GC was run since last iteration (cool!), reset timer:
	54	+	\| major_gcs > major_gcs_prev -> do
	55	+	startTimer >>= go gcs major_gcs False
56	56
57		-	-- we are idle and its a good time to do a GC, or we're overdue and must run a GC:
58		-	\| areIdle \|\| areOverdue -> do
59		-	when (areOverdue && not areIdle) $
60		-	logger $
61		-	UnstructuredLog LevelWarn $
62		-	"Overdue for a major GC: forcing one even though we don't appear to be idle"
63		-	performMajorGC
64		-	startTimer >>= go (gcs + 1) (major_gcs + 1)
	57	+	-- we are idle and its a good time to do a GC, or we're overdue and must run a GC:
	58	+	\| areIdle \|\| areOverdue -> do
	59	+	-- If we performed a GC last time and nothing was promoted meantime
	60	+	-- (minor GCs are the same) running a cheaper minor GC should
	61	+	-- suffice to perform any new due finalizers:
	62	+	if lastIterationPerformedGC && areIdle
	63	+	then do
	64	+	performMinorGC
	65	+	startTimer >>= go (gcs + 1) major_gcs True
	66	+	else do
	67	+	when (areOverdue && not areIdle)
	68	+	$ logger
	69	+	$ UnstructuredLog LevelWarn
	70	+	$ "Overdue for a major GC: forcing one even though we don't appear to be idle"
	71	+	performMajorGC
	72	+	startTimer >>= go (gcs + 1) (major_gcs + 1) True
65	73
66	74		-- else keep the timer running, waiting for us to go idle:
67	75		\| otherwise -> do
68	76		C.sleep idleInterval
69		-	go gcs major_gcs timerSinceLastMajorGC
	77	+	go gcs major_gcs False timerSinceLastMajorGC
70	78