Fix bug in conflict counting. (22d44325) · Commits · Glasgow Haskell Compiler / Packages / Cabal

Commit 22d44325 authored 7 years ago by kristenk

Fix bug in conflict counting.

In Explore.hs, the solver calculates a conflict set corresponding to the option
to not choose a value for each goal, called 'initial'. That conflict set should
be added to the ConflictMap when the current goal causes a conflict. However,
there was a bug, and the solver added 'initial' to the ConflictMap at every
level.

The bug meant that the solver preferred all goals that it had already chosen.
If a new goal started to cause conflicts, it would take a while for the solver
to start preferring the new goal over the ones that it had previously seen.
See #4595 for an example where this problem caused longer backjumps and slowed
down the solver.

Testing

I ran "cabal install --dry-run" for all packages on Hackage with master and the branch with a 90 second timeout, GHC 8.0.1, and index state 2017-07-08T04:20:18Z. Then I filtered out all packages where both runs had the same result (success or failure) and the times were within 10%. I repeated that process three times to eliminate packages that had different run times due to noise. Then I ran "cabal install --dry-run --max-backjumps=-1" on the remaining packages and averaged three runs.

Since this branch changes a goal-ordering heuristic, I expected a lot of changes in run time in either direction. Out of 105 changes, 83 were faster, 20 were slower, and 2 involved a timeout on both branches. (The two that timed out had different run times before I removed the backjump limit.)

package master result master time (seconds) branch result branch time (seconds) speedup
AesonBson solution 3.06 solution 2.59 1.18
DisTract no solution 1.48 no solution 1.34 1.1
GPipe-Examples timeout 90.01 no solution 2.11 -
GuiTV solution 2.54 solution 16.05 0.16
Phsu solution 3.49 solution 1.83 1.9
Ranka no solution 2.05 no solution 1.65 1.25
Rlang-QQ no solution 2.97 no solution 1.89 1.57
SourceGraph timeout 90.04 no solution 11.53 -
Validation no solution 2.1 no solution 6.59 0.32
WebCont no solution 2.04 no solution 1.6 1.28
acme-everything timeout 90.02 timeout 90 -
aeson-t solution 2.04 solution 1.81 1.13
alsa-gui no solution 1.62 no solution 1.86 0.87
aviation-cessna172-diagrams no solution 2.56 no solution 2.29 1.12
aws-dynamodb-conduit no solution 2.22 no solution 1.83 1.22
azure-servicebus no solution 5.18 no solution 2.87 1.8
bamboo-theme-mini-html5 no solution 2.51 no solution 2 1.26
bitcoin-payment-channel solution 3.42 solution 2.73 1.25
bittorrent no solution 2.75 no solution 2.4 1.15
blaze-builder-enumerator no solution 1.62 no solution 1.88 0.86
blunt solution 2.99 solution 2.5 1.19
cash no solution 1.33 no solution 1.53 0.87
cheapskate-terminal no solution 2.04 no solution 1.62 1.26
clckwrks-plugin-bugs no solution 3.85 no solution 5.78 0.67
cmdtheline no solution 1.96 no solution 1.63 1.2
colchis no solution 1.99 no solution 2.23 0.89
collada-types no solution 1.86 no solution 1.66 1.12
convertible-text solution 1.61 solution 1.83 0.88
cqrs-example no solution 2.64 no solution 2.32 1.14
dixi solution 4.44 solution 4.03 1.1
ethereum-client-haskell no solution 1.84 no solution 2.45 0.75
flowdock no solution 2.46 no solution 3.19 0.77
geniserver no solution 5.34 no solution 4.84 1.1
ghc-imported-from solution 4.59 solution 2.9 1.58
gps2htmlReport solution 3.08 solution 5.58 0.55
guarded-rewriting solution 1.54 solution 1.34 1.14
hack2-handler-happstack-server no solution 1.76 no solution 2 0.88
halma-telegram-bot solution 4.27 solution 3.37 1.27
happs-tutorial no solution 2.08 no solution 1.86 1.12
happstack no solution 3.08 no solution 5.86 0.53
happstack-facebook timeout 90.01 timeout 90.03 -
haskelldb-hsql-mysql no solution 1.73 no solution 1.5 1.16
hdbi no solution 1.92 no solution 1.66 1.15
hdbi-postgresql no solution 3.05 no solution 1.95 1.56
hdbi-sqlite no solution 1.91 no solution 1.69 1.13
hexpat-iteratee no solution 2.61 no solution 1.84 1.42
hist-pl no solution 2.69 no solution 2.36 1.14
hscd no solution 2.53 no solution 1.59 1.59
http-client-lens no solution 3.63 no solution 1.96 1.85
hubris no solution 3.62 no solution 1.63 2.22
infinity no solution 1.34 no solution 1.5 0.89
iteratee-parsec no solution 2.01 no solution 1.74 1.16
json-togo no solution 1.86 no solution 1.65 1.13
lat no solution 2.87 no solution 1.86 1.55
liquidhaskell solution 3.34 solution 2.25 1.48
manatee-core no solution 1.79 no solution 1.6 1.12
manatee-curl no solution 8.44 no solution 2.73 3.09
manatee-editor no solution 5.05 no solution 2.81 1.8
manatee-filemanager no solution 29.09 no solution 2.96 9.82
manatee-imageviewer no solution 1.78 no solution 1.57 1.13
manatee-mplayer no solution 8.98 no solution 4.05 2.22
manatee-terminal no solution 3.19 no solution 2.41 1.32
minimung no solution 1.86 no solution 1.57 1.19
monoids no solution 3.02 no solution 2.68 1.13
mprover no solution 1.89 no solution 1.54 1.23
ms no solution 8.04 no solution 4.35 1.85
music-sibelius solution 3.1 solution 2.5 1.24
nerf solution 22.54 solution 3.09 7.29
nomyx-api solution 5.46 solution 4.39 1.24
nomyx-library solution 2.08 solution 1.86 1.11
nomyx-server no solution 4.83 no solution 3.92 1.23
opaleye-classy no solution 2.07 no solution 3.58 0.58
openflow no solution 1.95 no solution 1.66 1.18
ot no solution 3.37 no solution 1.95 1.73
paypal-api no solution 1.89 no solution 1.64 1.15
pdf-slave-server no solution 3.21 no solution 2.15 1.49
phooey solution 2.55 solution 16.24 0.16
pipes-cereal-plus solution 1.85 solution 1.65 1.12
pocket-dns no solution 2.71 no solution 2.08 1.3
pontarius-mediaserver no solution 2.29 no solution 2.7 0.85
precis no solution 2.53 no solution 3.23 0.78
prove-everywhere-server no solution 2.19 no solution 1.92 1.14
quickbooks no solution 5.86 no solution 5.17 1.13
rbpcp-api solution 2.35 solution 2.13 1.11
react-haskell timeout 90.02 no solution 71.21 -
regex-xmlschema no solution 1.34 no solution 1.51 0.89
remote-json-server solution 2.1 solution 1.8 1.16
scholdoc-citeproc no solution 3 no solution 1.92 1.57
scion-browser no solution 5.21 no solution 4.65 1.12
semdoc no solution 4.21 no solution 3.04 1.39
servant-auth-token-rocksdb no solution 4.68 no solution 2.32 2.02
snaplet-auth-acid no solution 2.25 no solution 1.99 1.13
snaplet-stripe no solution 3.46 no solution 2.97 1.16
sssp no solution 3.3 no solution 2.79 1.18
target solution 2.8 solution 2.11 1.32
tls-extra no solution 2.74 no solution 2.36 1.16
twentefp-rosetree no solution 1.69 no solution 1.97 0.86
twitter-enumerator no solution 28.39 no solution 2.16 13.15
wai-middleware-cache no solution 1.95 no solution 1.56 1.25
wai-middleware-catch no solution 1.9 no solution 1.54 1.24
wai-middleware-route solution 11.9 solution 1.62 7.34
xml2json no solution 2.27 no solution 1.68 1.35
yesod-auth-account-fork solution 3.33 solution 2.87 1.16
yesod-comments no solution 25.6 no solution 14.44 1.77
yesod-pure solution 7.99 solution 4.45 1.79

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+ 5

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View file @ 22d44325

@@ -48,7 +48,10 @@ backjump :: EnableBackjumping -> Var QPN
          -> ConflictSet -> W.WeightedPSQ w k (ConflictMap -> ConflictSetLog a)
          -> ConflictMap -> ConflictSetLog a
 backjump (EnableBackjumping enableBj) var initial xs =
     F.foldr combine logBackjump xs initial
     F.foldr combine (\cs !cm -> logBackjump cs $ updateCM initial cm) xs initial
                       -- 'intial' instead of 'cs' here ---^
                       -- since we do not want to double-count the
                       -- additionally accumulated conflicts.
   where
     combine :: forall a . (ConflictMap -> ConflictSetLog a)
             -> (ConflictSet -> ConflictMap -> ConflictSetLog a)
@@ -61,10 +64,7 @@ backjump (EnableBackjumping enableBj) var initial xs =
           | otherwise                            = f (csAcc `CS.union` cs) cm'
     logBackjump :: ConflictSet -> ConflictMap -> ConflictSetLog a
     logBackjump cs !cm = failWith (Failure cs Backjump) (cs, updateCM initial cm)
                                    -- 'intial' instead of 'cs' here ---^
                                    -- since we do not want to double-count the
                                    -- additionally accumulated conflicts.
     logBackjump cs cm = failWith (Failure cs Backjump) (cs, cm)
 type ConflictSetLog = RetryLog Message (ConflictSet, ConflictMap)
-...

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@@ -103,7 +103,7 @@ trying: exe-0.1.0.0 (user goal)
 next goal: src (dependency of exe-0.1.0.0)
 rejecting: src-<VERSION>/installed-<HASH>... (conflict: src => mylib==0.1.0.0/installed-0.1..., src => mylib==0.1.0.0/installed-0.1...)
 fail (backjumping, conflict set: exe, src)
 After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: exe (3), src (2)Trying configure anyway.
 After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: exe (2), src (2)Trying configure anyway.
 Configuring exe-0.1.0.0...
 # Setup build
 Preprocessing executable 'exe' for exe-0.1.0.0..
-...

+ 1

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@@ -8,6 +8,6 @@ next goal: setup-dep (user goal)
 rejecting: setup-dep-2.0 (conflict: pkg => setup-dep==1.*)
 rejecting: setup-dep-1.0 (constraint from user target requires ==2.0)
 fail (backjumping, conflict set: pkg, setup-dep)
 After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: pkg (4), setup-dep (3)
 After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: setup-dep (3), pkg (2)
 # pkg my-exe
 Main.hs: setup-dep from repo

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@@ -5,7 +5,7 @@ Could not resolve dependencies:
 trying: Exe-0.1.0.0 (user goal)
 unknown package: totally-impossible-dependency-to-fill (dependency of Exe-0.1.0.0)
 fail (backjumping, conflict set: Exe, totally-impossible-dependency-to-fill)
 After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: Exe (3), totally-impossible-dependency-to-fill (1)Trying configure anyway.
 After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: Exe (2), totally-impossible-dependency-to-fill (1)Trying configure anyway.
 Configuring executable 'goodexe' for Exe-0.1.0.0..
 # Setup build
 Preprocessing executable 'goodexe' for Exe-0.1.0.0..
-...

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