/root/.sdkman/candidates/java/current/bin/java -Xmx8000000000 -Xss4m -jar ./plugins/org.eclipse.equinox.launcher_1.5.800.v20200727-1323.jar -data @noDefault -ultimatedata ./data -s ../benchexec/../../../trunk/examples/settings/gemcutter/NewStatesSleep.epf --traceabstraction.dfs.order.used.in.por LOOP_LOCKSTEP --traceabstraction.additional.conditional.commutativity.checking IA --traceabstraction.criterion.for.conditional.commutativity.checking SLEEP_SET -tc ../benchexec/../../../trunk/examples/toolchains/AutomizerBplInline.xml -i ../../../trunk/examples/concurrent/bpl/weaver-benchmarks/generated/unroll-cond-5.wvr.bpl -------------------------------------------------------------------------------- This is Ultimate 0.2.4-wip.dk.conditional-comm-faa7b7a-m [2024-04-27 03:08:35,632 INFO L188 SettingsManager]: Resetting all preferences to default values... [2024-04-27 03:08:35,696 INFO L114 SettingsManager]: Loading settings from /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/../benchexec/../../../trunk/examples/settings/gemcutter/NewStatesSleep.epf [2024-04-27 03:08:35,699 WARN L101 SettingsManager]: Preference file contains the following unknown settings: [2024-04-27 03:08:35,699 WARN L103 SettingsManager]: * de.uni_freiburg.informatik.ultimate.core.Log level for class [2024-04-27 03:08:35,733 INFO L130 SettingsManager]: Preferences different from defaults after loading the file: [2024-04-27 03:08:35,734 INFO L151 SettingsManager]: Preferences of UltimateCore differ from their defaults: [2024-04-27 03:08:35,734 INFO L153 SettingsManager]: * Log level for class=de.uni_freiburg.informatik.ultimate.lib.smtlibutils.quantifier.QuantifierPusher=ERROR; [2024-04-27 03:08:35,735 INFO L151 SettingsManager]: Preferences of Boogie Procedure Inliner differ from their defaults: [2024-04-27 03:08:35,738 INFO L153 SettingsManager]: * Ignore calls to procedures called more than once=ONLY_FOR_SEQUENTIAL_PROGRAMS [2024-04-27 03:08:35,738 INFO L151 SettingsManager]: Preferences of BlockEncodingV2 differ from their defaults: [2024-04-27 03:08:35,738 INFO L153 SettingsManager]: * Create parallel compositions if possible=false [2024-04-27 03:08:35,738 INFO L153 SettingsManager]: * Use SBE=true [2024-04-27 03:08:35,740 INFO L151 SettingsManager]: Preferences of CACSL2BoogieTranslator differ from their defaults: [2024-04-27 03:08:35,740 INFO L153 SettingsManager]: * Pointer base address is valid at dereference=IGNORE [2024-04-27 03:08:35,740 INFO L153 SettingsManager]: * sizeof long=4 [2024-04-27 03:08:35,740 INFO L153 SettingsManager]: * Overapproximate operations on floating types=true [2024-04-27 03:08:35,740 INFO L153 SettingsManager]: * sizeof POINTER=4 [2024-04-27 03:08:35,740 INFO L153 SettingsManager]: * Check division by zero=IGNORE [2024-04-27 03:08:35,741 INFO L153 SettingsManager]: * Pointer to allocated memory at dereference=IGNORE [2024-04-27 03:08:35,741 INFO L153 SettingsManager]: * If two pointers are subtracted or compared they have the same base address=IGNORE [2024-04-27 03:08:35,742 INFO L153 SettingsManager]: * Check array bounds for arrays that are off heap=IGNORE [2024-04-27 03:08:35,742 INFO L153 SettingsManager]: * sizeof long double=12 [2024-04-27 03:08:35,742 INFO L153 SettingsManager]: * Check if freed pointer was valid=false [2024-04-27 03:08:35,742 INFO L153 SettingsManager]: * Use constant arrays=true [2024-04-27 03:08:35,742 INFO L151 SettingsManager]: Preferences of RCFGBuilder differ from their defaults: [2024-04-27 03:08:35,742 INFO L153 SettingsManager]: * Size of a code block=SequenceOfStatements [2024-04-27 03:08:35,743 INFO L153 SettingsManager]: * To the following directory=./dump/ [2024-04-27 03:08:35,743 INFO L153 SettingsManager]: * SMT solver=External_DefaultMode [2024-04-27 03:08:35,743 INFO L153 SettingsManager]: * Command for external solver=z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in -t:2000 [2024-04-27 03:08:35,744 INFO L151 SettingsManager]: Preferences of TraceAbstraction differ from their defaults: [2024-04-27 03:08:35,744 INFO L153 SettingsManager]: * Compute Interpolants along a Counterexample=FPandBP [2024-04-27 03:08:35,744 INFO L153 SettingsManager]: * Command for external solver=z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in [2024-04-27 03:08:35,744 INFO L153 SettingsManager]: * Apply one-shot large block encoding in concurrent analysis=false [2024-04-27 03:08:35,744 INFO L153 SettingsManager]: * Partial Order Reduction in concurrent analysis=SLEEP_NEW_STATES [2024-04-27 03:08:35,744 INFO L153 SettingsManager]: * Positions where we compute the Hoare Annotation=LoopHeads [2024-04-27 03:08:35,745 INFO L153 SettingsManager]: * Trace refinement strategy=CAMEL [2024-04-27 03:08:35,745 INFO L153 SettingsManager]: * Automaton type used in concurrency analysis=PARTIAL_ORDER_FA [2024-04-27 03:08:35,745 INFO L153 SettingsManager]: * Compute Hoare Annotation of negated interpolant automaton, abstraction and CFG=true [2024-04-27 03:08:35,745 INFO L153 SettingsManager]: * SMT solver=External_ModelsAndUnsatCoreMode WARNING: An illegal reflective access operation has occurred WARNING: Illegal reflective access by com.sun.xml.bind.v2.runtime.reflect.opt.Injector$1 (file:/storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/plugins/com.sun.xml.bind_2.2.0.v201505121915.jar) to method java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int) WARNING: Please consider reporting this to the maintainers of com.sun.xml.bind.v2.runtime.reflect.opt.Injector$1 WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations WARNING: All illegal access operations will be denied in a future release Applying setting for plugin de.uni_freiburg.informatik.ultimate.plugins.generator.traceabstraction: DFS Order used in POR -> LOOP_LOCKSTEP Applying setting for plugin de.uni_freiburg.informatik.ultimate.plugins.generator.traceabstraction: Additional conditional commutativity checking -> IA Applying setting for plugin de.uni_freiburg.informatik.ultimate.plugins.generator.traceabstraction: Criterion for conditional commutativity checking -> SLEEP_SET [2024-04-27 03:08:35,947 INFO L75 nceAwareModelManager]: Repository-Root is: /tmp [2024-04-27 03:08:35,973 INFO L261 ainManager$Toolchain]: [Toolchain 1]: Applicable parser(s) successfully (re)initialized [2024-04-27 03:08:35,975 INFO L217 ainManager$Toolchain]: [Toolchain 1]: Toolchain selected. [2024-04-27 03:08:35,976 INFO L270 PluginConnector]: Initializing Boogie PL CUP Parser... [2024-04-27 03:08:35,978 INFO L274 PluginConnector]: Boogie PL CUP Parser initialized [2024-04-27 03:08:35,979 INFO L431 ainManager$Toolchain]: [Toolchain 1]: Parsing single file: /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/../../../trunk/examples/concurrent/bpl/weaver-benchmarks/generated/unroll-cond-5.wvr.bpl [2024-04-27 03:08:35,979 INFO L110 BoogieParser]: Parsing: '/storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/../../../trunk/examples/concurrent/bpl/weaver-benchmarks/generated/unroll-cond-5.wvr.bpl' [2024-04-27 03:08:36,022 INFO L299 ainManager$Toolchain]: ####################### [Toolchain 1] ####################### [2024-04-27 03:08:36,024 INFO L133 ToolchainWalker]: Walking toolchain with 4 elements. [2024-04-27 03:08:36,025 INFO L112 PluginConnector]: ------------------------Boogie Procedure Inliner---------------------------- [2024-04-27 03:08:36,025 INFO L270 PluginConnector]: Initializing Boogie Procedure Inliner... [2024-04-27 03:08:36,035 INFO L274 PluginConnector]: Boogie Procedure Inliner initialized [2024-04-27 03:08:36,062 INFO L184 PluginConnector]: Executing the observer TypeChecker from plugin Boogie Procedure Inliner for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 27.04 03:08:36" (1/1) ... [2024-04-27 03:08:36,069 INFO L184 PluginConnector]: Executing the observer Inliner from plugin Boogie Procedure Inliner for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 27.04 03:08:36" (1/1) ... [2024-04-27 03:08:36,078 INFO L138 Inliner]: procedures = 3, calls = 2, calls flagged for inlining = 0, calls inlined = 0, statements flattened = 0 [2024-04-27 03:08:36,079 INFO L131 PluginConnector]: ------------------------ END Boogie Procedure Inliner---------------------------- [2024-04-27 03:08:36,081 INFO L112 PluginConnector]: ------------------------Boogie Preprocessor---------------------------- [2024-04-27 03:08:36,081 INFO L270 PluginConnector]: Initializing Boogie Preprocessor... [2024-04-27 03:08:36,081 INFO L274 PluginConnector]: Boogie Preprocessor initialized [2024-04-27 03:08:36,089 INFO L184 PluginConnector]: Executing the observer EnsureBoogieModelObserver from plugin Boogie Preprocessor for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 27.04 03:08:36" (1/1) ... [2024-04-27 03:08:36,089 INFO L184 PluginConnector]: Executing the observer TypeChecker from plugin Boogie Preprocessor for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 27.04 03:08:36" (1/1) ... [2024-04-27 03:08:36,090 INFO L184 PluginConnector]: Executing the observer ConstExpander from plugin Boogie Preprocessor for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 27.04 03:08:36" (1/1) ... [2024-04-27 03:08:36,091 INFO L184 PluginConnector]: Executing the observer StructExpander from plugin Boogie Preprocessor for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 27.04 03:08:36" (1/1) ... [2024-04-27 03:08:36,093 INFO L184 PluginConnector]: Executing the observer UnstructureCode from plugin Boogie Preprocessor for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 27.04 03:08:36" (1/1) ... [2024-04-27 03:08:36,095 INFO L184 PluginConnector]: Executing the observer FunctionInliner from plugin Boogie Preprocessor for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 27.04 03:08:36" (1/1) ... [2024-04-27 03:08:36,096 INFO L184 PluginConnector]: Executing the observer LTLStepAnnotator from plugin Boogie Preprocessor for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 27.04 03:08:36" (1/1) ... [2024-04-27 03:08:36,097 INFO L184 PluginConnector]: Executing the observer BoogieSymbolTableConstructor from plugin Boogie Preprocessor for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 27.04 03:08:36" (1/1) ... [2024-04-27 03:08:36,098 INFO L131 PluginConnector]: ------------------------ END Boogie Preprocessor---------------------------- [2024-04-27 03:08:36,099 INFO L112 PluginConnector]: ------------------------RCFGBuilder---------------------------- [2024-04-27 03:08:36,099 INFO L270 PluginConnector]: Initializing RCFGBuilder... [2024-04-27 03:08:36,099 INFO L274 PluginConnector]: RCFGBuilder initialized [2024-04-27 03:08:36,100 INFO L184 PluginConnector]: Executing the observer RCFGBuilderObserver from plugin RCFGBuilder for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 27.04 03:08:36" (1/1) ... [2024-04-27 03:08:36,105 INFO L173 SolverBuilder]: Constructing external solver with command: z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in -t:2000 [2024-04-27 03:08:36,118 INFO L189 MonitoredProcess]: No working directory specified, using /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 [2024-04-27 03:08:36,137 INFO L229 MonitoredProcess]: Starting monitored process 1 with /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in -t:2000 (exit command is (exit), workingDir is null) [2024-04-27 03:08:36,148 INFO L327 MonitoredProcess]: [MP /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in -t:2000 (1)] Waiting until timeout for monitored process [2024-04-27 03:08:36,194 INFO L124 BoogieDeclarations]: Specification and implementation of procedure thread1 given in one single declaration [2024-04-27 03:08:36,195 INFO L130 BoogieDeclarations]: Found specification of procedure thread1 [2024-04-27 03:08:36,195 INFO L138 BoogieDeclarations]: Found implementation of procedure thread1 [2024-04-27 03:08:36,195 INFO L124 BoogieDeclarations]: Specification and implementation of procedure thread2 given in one single declaration [2024-04-27 03:08:36,195 INFO L130 BoogieDeclarations]: Found specification of procedure thread2 [2024-04-27 03:08:36,196 INFO L138 BoogieDeclarations]: Found implementation of procedure thread2 [2024-04-27 03:08:36,196 INFO L124 BoogieDeclarations]: Specification and implementation of procedure ULTIMATE.start given in one single declaration [2024-04-27 03:08:36,196 INFO L130 BoogieDeclarations]: Found specification of procedure ULTIMATE.start [2024-04-27 03:08:36,196 INFO L138 BoogieDeclarations]: Found implementation of procedure ULTIMATE.start [2024-04-27 03:08:36,197 WARN L213 CfgBuilder]: User set CodeBlockSize to SequenceOfStatements but program contains fork statements. Overwriting the user preferences and setting CodeBlockSize to OneNontrivialStatement [2024-04-27 03:08:36,241 INFO L241 CfgBuilder]: Building ICFG [2024-04-27 03:08:36,243 INFO L267 CfgBuilder]: Building CFG for each procedure with an implementation [2024-04-27 03:08:36,426 INFO L282 CfgBuilder]: Performing block encoding [2024-04-27 03:08:36,534 INFO L304 CfgBuilder]: Using the 1 location(s) as analysis (start of procedure ULTIMATE.start) [2024-04-27 03:08:36,535 INFO L309 CfgBuilder]: Removed 2 assume(true) statements. [2024-04-27 03:08:36,536 INFO L201 PluginConnector]: Adding new model unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.plugins.generator.rcfgbuilder CFG 27.04 03:08:36 BoogieIcfgContainer [2024-04-27 03:08:36,536 INFO L131 PluginConnector]: ------------------------ END RCFGBuilder---------------------------- [2024-04-27 03:08:36,538 INFO L112 PluginConnector]: ------------------------TraceAbstraction---------------------------- [2024-04-27 03:08:36,538 INFO L270 PluginConnector]: Initializing TraceAbstraction... [2024-04-27 03:08:36,560 INFO L274 PluginConnector]: TraceAbstraction initialized [2024-04-27 03:08:36,560 INFO L184 PluginConnector]: Executing the observer TraceAbstractionObserver from plugin TraceAbstraction for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 27.04 03:08:36" (1/2) ... [2024-04-27 03:08:36,561 INFO L204 PluginConnector]: Invalid model from TraceAbstraction for observer de.uni_freiburg.informatik.ultimate.plugins.generator.traceabstraction.TraceAbstractionObserver@7a2141fd and model type unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.plugins.generator.traceabstraction AST 27.04 03:08:36, skipping insertion in model container [2024-04-27 03:08:36,562 INFO L184 PluginConnector]: Executing the observer TraceAbstractionObserver from plugin TraceAbstraction for "unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.plugins.generator.rcfgbuilder CFG 27.04 03:08:36" (2/2) ... [2024-04-27 03:08:36,563 INFO L112 eAbstractionObserver]: Analyzing ICFG unroll-cond-5.wvr.bpl [2024-04-27 03:08:36,569 WARN L145 ceAbstractionStarter]: Switching off computation of Hoare annotation because input is a concurrent program [2024-04-27 03:08:36,575 INFO L203 ceAbstractionStarter]: Automizer settings: Hoare:false NWA Interpolation:FPandBP Determinization: PREDICATE_ABSTRACTION [2024-04-27 03:08:36,576 INFO L162 ceAbstractionStarter]: Applying trace abstraction to program that has 1 error locations. [2024-04-27 03:08:36,576 INFO L514 ceAbstractionStarter]: Constructing petrified ICFG for 1 thread instances. [2024-04-27 03:08:36,596 INFO L144 ThreadInstanceAdder]: Constructed 2 joinOtherThreadTransitions. [2024-04-27 03:08:36,623 INFO L100 denceProviderFactory]: Independence Relation #1: [IndependenceType=SEMANTIC, AbstractionType=NONE, UseConditional=true, UseSemiCommutativity=true, Solver=Z3, SolverTimeout=1000ms] [2024-04-27 03:08:36,623 INFO L173 SolverBuilder]: Constructing external solver with command: z3 -smt2 -in SMTLIB2_COMPLIANT=true -t:1000 [2024-04-27 03:08:36,624 INFO L189 MonitoredProcess]: No working directory specified, using /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 [2024-04-27 03:08:36,635 INFO L229 MonitoredProcess]: Starting monitored process 2 with /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 -smt2 -in SMTLIB2_COMPLIANT=true -t:1000 (exit command is (exit), workingDir is null) [2024-04-27 03:08:36,636 INFO L327 MonitoredProcess]: [MP /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 -smt2 -in SMTLIB2_COMPLIANT=true -t:1000 (2)] Waiting until timeout for monitored process [2024-04-27 03:08:36,687 INFO L187 artialOrderCegarLoop]: Running PartialOrderCegarLoop with 1 independence relations. [2024-04-27 03:08:36,712 INFO L160 PredicateUnifier]: Initialized classic predicate unifier [2024-04-27 03:08:36,715 INFO L356 AbstractCegarLoop]: ======== Iteration 0 == of CEGAR loop == AllErrorsAtOnce ======== [2024-04-27 03:08:36,725 INFO L357 AbstractCegarLoop]: Settings: SEPARATE_VIOLATION_CHECK=true, mInterprocedural=true, mMaxIterations=1000000, mWatchIteration=1000000, mArtifact=RCFG, mInterpolation=FPandBP, mInterpolantAutomaton=STRAIGHT_LINE, mDumpAutomata=false, mAutomataFormat=ATS_NUMERATE, mDumpPath=., mDeterminiation=PREDICATE_ABSTRACTION, mMinimize=MINIMIZE_SEVPA, mHoare=true, mAutomataTypeConcurrency=PARTIAL_ORDER_FA, mHoareTripleChecks=INCREMENTAL, mHoareAnnotationPositions=LoopHeads, mDumpOnlyReuseAutomata=false, mLimitTraceHistogram=0, mErrorLocTimeLimit=0, mLimitPathProgramCount=0, mCollectInterpolantStatistics=true, mHeuristicEmptinessCheck=false, mHeuristicEmptinessCheckAStarHeuristic=ZERO, mHeuristicEmptinessCheckAStarHeuristicRandomSeed=1337, mHeuristicEmptinessCheckSmtFeatureScoringMethod=DAGSIZE, mSMTFeatureExtraction=false, mSMTFeatureExtractionDumpPath=., mOverrideInterpolantAutomaton=false, mMcrInterpolantMethod=WP, mPorIndependenceSettings=[Lde.uni_freiburg.informatik.ultimate.lib.tracecheckerutils.partialorder.independence.IndependenceSettings;@1b7216e, mLbeIndependenceSettings=[IndependenceType=SEMANTIC, AbstractionType=NONE, UseConditional=false, UseSemiCommutativity=true, Solver=Z3, SolverTimeout=1000ms], mConComChecker=IA, mConComCheckerCriterion=SLEEP_SET, mConComCheckerLimitedChecksCriterion=false, mConComCheckerCriterionLimit=1, mConComCheckerRandomProb=100, mConComCheckerRandomSeed=123, mConComCheckerConditionCriterion=false [2024-04-27 03:08:36,730 INFO L358 AbstractCegarLoop]: Starting to check reachability of 3 error locations. [2024-04-27 03:08:36,764 INFO L420 AbstractCegarLoop]: === Iteration 1 === Targeting ULTIMATE.startErr0ASSERT_VIOLATIONASSERT === [ULTIMATE.startErr0ASSERT_VIOLATIONASSERT, ULTIMATE.startErr0INUSE_VIOLATIONSUFFICIENT_THREAD_INSTANCES, ULTIMATE.startErr1INUSE_VIOLATIONSUFFICIENT_THREAD_INSTANCES] === [2024-04-27 03:08:36,768 INFO L160 PredicateUnifier]: Initialized classic predicate unifier [2024-04-27 03:08:36,768 INFO L85 PathProgramCache]: Analyzing trace with hash 1307002836, now seen corresponding path program 1 times [2024-04-27 03:08:36,777 INFO L118 FreeRefinementEngine]: Executing refinement strategy CAMEL [2024-04-27 03:08:36,778 INFO L334 FreeRefinementEngine]: Using trace check IpTcStrategyModuleSmtInterpolCraig [1845651807] [2024-04-27 03:08:36,778 INFO L95 rtionOrderModulation]: Keeping assertion order NOT_INCREMENTALLY [2024-04-27 03:08:36,778 INFO L127 SolverBuilder]: Constructing new instance of SMTInterpol with explicit timeout -1 ms and remaining time -1 ms [2024-04-27 03:08:36,893 INFO L136 AnnotateAndAsserter]: Conjunction of SSA is unsat [2024-04-27 03:08:37,162 INFO L134 CoverageAnalysis]: Checked inductivity of 0 backedges. 0 proven. 0 refuted. 0 times theorem prover too weak. 0 trivial. 0 not checked. [2024-04-27 03:08:37,162 INFO L136 FreeRefinementEngine]: Strategy CAMEL found an infeasible trace [2024-04-27 03:08:37,162 INFO L334 FreeRefinementEngine]: Using interpolant generator IpTcStrategyModuleSmtInterpolCraig [1845651807] [2024-04-27 03:08:37,163 INFO L158 FreeRefinementEngine]: IpTcStrategyModuleSmtInterpolCraig [1845651807] provided 1 perfect and 0 imperfect interpolant sequences [2024-04-27 03:08:37,163 INFO L185 FreeRefinementEngine]: Found 1 perfect and 0 imperfect interpolant sequences. [2024-04-27 03:08:37,163 INFO L198 FreeRefinementEngine]: Number of different interpolants: perfect sequences [4] imperfect sequences [] total 4 [2024-04-27 03:08:37,164 INFO L121 tionRefinementEngine]: Using interpolant automaton builder IpAbStrategyModuleStraightlineAll [1561200729] [2024-04-27 03:08:37,165 INFO L85 oduleStraightlineAll]: Using 1 perfect interpolants to construct interpolant automaton [2024-04-27 03:08:37,170 INFO L571 AbstractCegarLoop]: INTERPOLANT automaton has 5 states [2024-04-27 03:08:37,170 INFO L100 FreeRefinementEngine]: Using predicate unifier PredicateUnifier provided by strategy CAMEL [2024-04-27 03:08:37,196 INFO L143 InterpolantAutomaton]: Constructing interpolant automaton starting with 5 interpolants. [2024-04-27 03:08:37,197 INFO L145 InterpolantAutomaton]: CoverageRelationStatistics Valid=9, Invalid=11, Unknown=0, NotChecked=0, Total=20 [2024-04-27 03:08:37,197 INFO L141 InterpolantAutomaton]: Switched to read-only mode: deterministic interpolant automaton has 2 states. [2024-04-27 03:08:37,199 INFO L495 AbstractCegarLoop]: Abstraction has currently 0 states, but on-demand construction may add more states [2024-04-27 03:08:37,200 INFO L496 AbstractCegarLoop]: INTERPOLANT automaton has has 5 states, 5 states have (on average 2.2) internal successors, (11), 4 states have internal predecessors, (11), 0 states have call successors, (0), 0 states have call predecessors, (0), 0 states have return successors, (0), 0 states have call predecessors, (0), 0 states have call successors, (0) [2024-04-27 03:08:37,200 INFO L154 InterpolantAutomaton]: Switched to On-DemandConstruction mode: deterministic interpolant automaton has 2 states. [2024-04-27 03:08:37,262 INFO L141 InterpolantAutomaton]: Switched to read-only mode: deterministic interpolant automaton has 4 states. [2024-04-27 03:08:37,262 WARN L477 AbstractCegarLoop]: Destroyed unattended storables created during the last iteration: SelfDestructingSolverStorable0 [2024-04-27 03:08:37,262 INFO L420 AbstractCegarLoop]: === Iteration 2 === Targeting ULTIMATE.startErr0ASSERT_VIOLATIONASSERT === [ULTIMATE.startErr0ASSERT_VIOLATIONASSERT, ULTIMATE.startErr0INUSE_VIOLATIONSUFFICIENT_THREAD_INSTANCES, ULTIMATE.startErr1INUSE_VIOLATIONSUFFICIENT_THREAD_INSTANCES] === [2024-04-27 03:08:37,263 INFO L160 PredicateUnifier]: Initialized classic predicate unifier [2024-04-27 03:08:37,263 INFO L85 PathProgramCache]: Analyzing trace with hash 1566523925, now seen corresponding path program 1 times [2024-04-27 03:08:37,263 INFO L118 FreeRefinementEngine]: Executing refinement strategy CAMEL [2024-04-27 03:08:37,263 INFO L334 FreeRefinementEngine]: Using trace check IpTcStrategyModuleSmtInterpolCraig [888481743] [2024-04-27 03:08:37,263 INFO L95 rtionOrderModulation]: Keeping assertion order NOT_INCREMENTALLY [2024-04-27 03:08:37,264 INFO L127 SolverBuilder]: Constructing new instance of SMTInterpol with explicit timeout -1 ms and remaining time -1 ms [2024-04-27 03:08:37,284 INFO L136 AnnotateAndAsserter]: Conjunction of SSA is unsat [2024-04-27 03:08:42,532 INFO L134 CoverageAnalysis]: Checked inductivity of 1 backedges. 0 proven. 1 refuted. 0 times theorem prover too weak. 0 trivial. 0 not checked. [2024-04-27 03:08:42,533 INFO L136 FreeRefinementEngine]: Strategy CAMEL found an infeasible trace [2024-04-27 03:08:42,533 INFO L334 FreeRefinementEngine]: Using interpolant generator IpTcStrategyModuleSmtInterpolCraig [888481743] [2024-04-27 03:08:42,533 INFO L158 FreeRefinementEngine]: IpTcStrategyModuleSmtInterpolCraig [888481743] provided 0 perfect and 1 imperfect interpolant sequences [2024-04-27 03:08:42,533 INFO L334 FreeRefinementEngine]: Using interpolant generator IpTcStrategyModuleZ3 [1143073263] [2024-04-27 03:08:42,534 INFO L95 rtionOrderModulation]: Keeping assertion order NOT_INCREMENTALLY [2024-04-27 03:08:42,534 INFO L173 SolverBuilder]: Constructing external solver with command: z3 -smt2 -in SMTLIB2_COMPLIANT=true [2024-04-27 03:08:42,534 INFO L189 MonitoredProcess]: No working directory specified, using /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 [2024-04-27 03:08:42,539 INFO L229 MonitoredProcess]: Starting monitored process 3 with /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 -smt2 -in SMTLIB2_COMPLIANT=true (exit command is (exit), workingDir is null) [2024-04-27 03:08:42,540 INFO L327 MonitoredProcess]: [MP /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 -smt2 -in SMTLIB2_COMPLIANT=true (3)] Waiting until timeout for monitored process [2024-04-27 03:08:42,616 INFO L136 AnnotateAndAsserter]: Conjunction of SSA is unsat [2024-04-27 03:08:42,618 INFO L262 TraceCheckSpWp]: Trace formula consists of 37 conjuncts, 16 conjunts are in the unsatisfiable core [2024-04-27 03:08:42,623 INFO L285 TraceCheckSpWp]: Computing forward predicates... Received shutdown request... [2024-04-27 03:23:10,336 WARN L340 MonitoredProcess]: [MP /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 -smt2 -in SMTLIB2_COMPLIANT=true -t:1000 (2)] Timeout while monitored process is still running, waiting 1000 ms for graceful end [2024-04-27 03:23:10,336 WARN L340 MonitoredProcess]: [MP /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in -t:2000 (1)] Timeout while monitored process is still running, waiting 1000 ms for graceful end [2024-04-27 03:23:10,336 WARN L340 MonitoredProcess]: [MP /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 -smt2 -in SMTLIB2_COMPLIANT=true (3)] Timeout while monitored process is still running, waiting 1000 ms for graceful end [2024-04-27 03:23:10,684 INFO L805 garLoopResultBuilder]: Registering result TIMEOUT for location ULTIMATE.startErr0ASSERT_VIOLATIONASSERT (2 of 3 remaining) [2024-04-27 03:23:10,689 INFO L552 MonitoredProcess]: [MP /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 -smt2 -in SMTLIB2_COMPLIANT=true (3)] Ended with exit code 0 [2024-04-27 03:23:10,889 WARN L477 AbstractCegarLoop]: Destroyed unattended storables created during the last iteration: 3 /storage/repos/ultimate/releaseScripts/default/UGemCutter-linux/z3 -smt2 -in SMTLIB2_COMPLIANT=true,SelfDestructingSolverStorable1 [2024-04-27 03:23:10,891 WARN L619 AbstractCegarLoop]: Verification canceled: while PartialOrderCegarLoop was analyzing trace of length 13 with TraceHistMax 1,while TraceCheckSpWp was constructing forward predicates,while PolyPacSimplificationTermWalker was simplifying a ATOM-1 term,while PolyPacSimplificationTermWalker was simplifying 2 xjuncts wrt. a ∧-37-3-2-3-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-1 context. [2024-04-27 03:23:10,892 INFO L805 garLoopResultBuilder]: Registering result TIMEOUT for location ULTIMATE.startErr0INUSE_VIOLATIONSUFFICIENT_THREAD_INSTANCES (1 of 3 remaining) [2024-04-27 03:23:10,893 INFO L805 garLoopResultBuilder]: Registering result TIMEOUT for location ULTIMATE.startErr1INUSE_VIOLATIONSUFFICIENT_THREAD_INSTANCES (0 of 3 remaining) [2024-04-27 03:23:10,992 INFO L448 BasicCegarLoop]: Path program histogram: [1, 1] [2024-04-27 03:23:10,995 INFO L228 ceAbstractionStarter]: Analysis of concurrent program completed with 1 thread instances [2024-04-27 03:23:10,995 INFO L178 ceAbstractionStarter]: Computing trace abstraction results [2024-04-27 03:23:10,998 INFO L201 PluginConnector]: Adding new model unroll-cond-5.wvr.bpl de.uni_freiburg.informatik.ultimate.plugins.generator.traceabstraction CFG 27.04 03:23:10 BasicIcfg [2024-04-27 03:23:10,998 INFO L131 PluginConnector]: ------------------------ END TraceAbstraction---------------------------- [2024-04-27 03:23:10,999 INFO L158 Benchmark]: Toolchain (without parser) took 874974.82ms. Allocated memory was 316.7MB in the beginning and 6.7GB in the end (delta: 6.4GB). Free memory was 288.6MB in the beginning and 6.4GB in the end (delta: -6.1GB). Peak memory consumption was 4.4GB. Max. memory is 8.0GB. [2024-04-27 03:23:10,999 INFO L158 Benchmark]: Boogie PL CUP Parser took 0.10ms. Allocated memory is still 167.8MB. Free memory is still 131.6MB. There was no memory consumed. Max. memory is 8.0GB. [2024-04-27 03:23:10,999 INFO L158 Benchmark]: Boogie Procedure Inliner took 54.61ms. Allocated memory is still 316.7MB. Free memory was 288.4MB in the beginning and 287.6MB in the end (delta: 820.9kB). Peak memory consumption was 2.1MB. Max. memory is 8.0GB. [2024-04-27 03:23:11,000 INFO L158 Benchmark]: Boogie Preprocessor took 17.68ms. Allocated memory is still 316.7MB. Free memory was 287.6MB in the beginning and 286.5MB in the end (delta: 1.0MB). Peak memory consumption was 1.0MB. Max. memory is 8.0GB. [2024-04-27 03:23:11,000 INFO L158 Benchmark]: RCFGBuilder took 437.04ms. Allocated memory is still 316.7MB. Free memory was 286.5MB in the beginning and 271.4MB in the end (delta: 15.1MB). Peak memory consumption was 14.7MB. Max. memory is 8.0GB. [2024-04-27 03:23:11,001 INFO L158 Benchmark]: TraceAbstraction took 874460.40ms. Allocated memory was 316.7MB in the beginning and 6.7GB in the end (delta: 6.4GB). Free memory was 270.4MB in the beginning and 6.4GB in the end (delta: -6.1GB). Peak memory consumption was 4.4GB. Max. memory is 8.0GB. [2024-04-27 03:23:11,002 INFO L338 ainManager$Toolchain]: ####################### End [Toolchain 1] ####################### --- Results --- * Results from de.uni_freiburg.informatik.ultimate.core: - StatisticsResult: Toolchain Benchmarks Benchmark results are: * Boogie PL CUP Parser took 0.10ms. Allocated memory is still 167.8MB. Free memory is still 131.6MB. There was no memory consumed. Max. memory is 8.0GB. * Boogie Procedure Inliner took 54.61ms. Allocated memory is still 316.7MB. Free memory was 288.4MB in the beginning and 287.6MB in the end (delta: 820.9kB). Peak memory consumption was 2.1MB. Max. memory is 8.0GB. * Boogie Preprocessor took 17.68ms. Allocated memory is still 316.7MB. Free memory was 287.6MB in the beginning and 286.5MB in the end (delta: 1.0MB). Peak memory consumption was 1.0MB. Max. memory is 8.0GB. * RCFGBuilder took 437.04ms. Allocated memory is still 316.7MB. Free memory was 286.5MB in the beginning and 271.4MB in the end (delta: 15.1MB). Peak memory consumption was 14.7MB. Max. memory is 8.0GB. * TraceAbstraction took 874460.40ms. Allocated memory was 316.7MB in the beginning and 6.7GB in the end (delta: 6.4GB). Free memory was 270.4MB in the beginning and 6.4GB in the end (delta: -6.1GB). Peak memory consumption was 4.4GB. Max. memory is 8.0GB. * Results from de.uni_freiburg.informatik.ultimate.plugins.generator.traceabstraction: - StatisticsResult: Independence relation #1 benchmarks ThreadSeparatingIndependenceRelation.Independence Queries: [ total: 55, independent: 36, independent conditional: 36, independent unconditional: 0, dependent: 19, dependent conditional: 19, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , ThreadSeparatingIndependenceRelation.Statistics on underlying relation: UnionIndependenceRelation.Independence Queries: [ total: 36, independent: 36, independent conditional: 36, independent unconditional: 0, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , UnionIndependenceRelation.Statistics on underlying relations: [ ConditionTransformingIndependenceRelation.Independence Queries: [ total: 36, independent: 36, independent conditional: 36, independent unconditional: 0, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , ConditionTransformingIndependenceRelation.Statistics on underlying relation: DisjunctiveConditionalIndependenceRelation.Independence Queries: [ total: 36, independent: 36, independent conditional: 36, independent unconditional: 0, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , DisjunctiveConditionalIndependenceRelation.Statistics on underlying relation: ConditionTransformingIndependenceRelation.Independence Queries: [ total: 36, independent: 36, independent conditional: 10, independent unconditional: 26, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , ConditionTransformingIndependenceRelation.Statistics on underlying relation: SemanticConditionEliminator.Independence Queries: [ total: 36, independent: 36, independent conditional: 10, independent unconditional: 26, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , SemanticConditionEliminator.Statistics on underlying relation: CachedIndependenceRelation.Independence Queries: [ total: 36, independent: 36, independent conditional: 10, independent unconditional: 26, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , CachedIndependenceRelation.Statistics on underlying relation: UnionIndependenceRelation.Independence Queries: [ total: 24, independent: 24, independent conditional: 6, independent unconditional: 18, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , UnionIndependenceRelation.Statistics on underlying relations: [ SyntacticIndependenceRelation.Independence Queries: [ total: 24, independent: 24, independent conditional: 0, independent unconditional: 24, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , ProtectedIndependenceRelation.Independence Queries: [ total: 0, independent: 0, independent conditional: 0, independent unconditional: 0, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , ProtectedIndependenceRelation.Statistics on underlying relation: SemanticIndependenceRelation.Independence Queries: [ total: 0, independent: 0, independent conditional: 0, independent unconditional: 0, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , SemanticIndependenceRelation.Query Time [ms]: [ total: 0, independent: 0, independent conditional: 0, independent unconditional: 0, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , Protected Queries: 0 ], Cache Queries: [ total: 36, independent: 12, independent conditional: 4, independent unconditional: 8, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 24, unknown conditional: 6, unknown unconditional: 18] , Statistics on independence cache: Total cache size (in pairs): 24, Positive cache size: 24, Positive conditional cache size: 6, Positive unconditional cache size: 18, Negative cache size: 0, Negative conditional cache size: 0, Negative unconditional cache size: 0, Unknown cache size: 0, Unknown conditional cache size: 0, Unknown unconditional cache size: 0, Eliminated conditions: 0, Maximal queried relation: 0, ConditionTransformingIndependenceRelation.Independence Queries: [ total: 36, independent: 36, independent conditional: 10, independent unconditional: 26, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , ConditionTransformingIndependenceRelation.Statistics on underlying relation: SemanticConditionEliminator.Independence Queries: [ total: 36, independent: 36, independent conditional: 10, independent unconditional: 26, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , SemanticConditionEliminator.Statistics on underlying relation: CachedIndependenceRelation.Independence Queries: [ total: 36, independent: 36, independent conditional: 10, independent unconditional: 26, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , CachedIndependenceRelation.Statistics on underlying relation: UnionIndependenceRelation.Independence Queries: [ total: 24, independent: 24, independent conditional: 6, independent unconditional: 18, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , UnionIndependenceRelation.Statistics on underlying relations: [ SyntacticIndependenceRelation.Independence Queries: [ total: 24, independent: 24, independent conditional: 0, independent unconditional: 24, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , ProtectedIndependenceRelation.Independence Queries: [ total: 0, independent: 0, independent conditional: 0, independent unconditional: 0, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , ProtectedIndependenceRelation.Statistics on underlying relation: SemanticIndependenceRelation.Independence Queries: [ total: 0, independent: 0, independent conditional: 0, independent unconditional: 0, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , SemanticIndependenceRelation.Query Time [ms]: [ total: 0, independent: 0, independent conditional: 0, independent unconditional: 0, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 0, unknown conditional: 0, unknown unconditional: 0] , Protected Queries: 0 ], Cache Queries: [ total: 36, independent: 12, independent conditional: 4, independent unconditional: 8, dependent: 0, dependent conditional: 0, dependent unconditional: 0, unknown: 24, unknown conditional: 6, unknown unconditional: 18] , Statistics on independence cache: Total cache size (in pairs): 24, Positive cache size: 24, Positive conditional cache size: 6, Positive unconditional cache size: 18, Negative cache size: 0, Negative conditional cache size: 0, Negative unconditional cache size: 0, Unknown cache size: 0, Unknown conditional cache size: 0, Unknown unconditional cache size: 0, Eliminated conditions: 0 ], Independence queries for same thread: 19 - TimeoutResultAtElement [Line: 69]: Timeout (TraceAbstraction) Unable to prove that assertion always holds Cancelled while PartialOrderCegarLoop was analyzing trace of length 13 with TraceHistMax 1,while TraceCheckSpWp was constructing forward predicates,while PolyPacSimplificationTermWalker was simplifying a ATOM-1 term,while PolyPacSimplificationTermWalker was simplifying 2 xjuncts wrt. a ∧-37-3-2-3-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-1 context. - TimeoutResultAtElement [Line: 64]: Timeout (TraceAbstraction) Unable to prove that petrification did provide enough thread instances (tool internal message) Cancelled while PartialOrderCegarLoop was analyzing trace of length 13 with TraceHistMax 1,while TraceCheckSpWp was constructing forward predicates,while PolyPacSimplificationTermWalker was simplifying a ATOM-1 term,while PolyPacSimplificationTermWalker was simplifying 2 xjuncts wrt. a ∧-37-3-2-3-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-1 context. - TimeoutResultAtElement [Line: 64]: Timeout (TraceAbstraction) Unable to prove that petrification did provide enough thread instances (tool internal message) Cancelled while PartialOrderCegarLoop was analyzing trace of length 13 with TraceHistMax 1,while TraceCheckSpWp was constructing forward predicates,while PolyPacSimplificationTermWalker was simplifying a ATOM-1 term,while PolyPacSimplificationTermWalker was simplifying 2 xjuncts wrt. a ∧-37-3-2-3-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-1 context. - StatisticsResult: Ultimate Automizer benchmark data with 1 thread instances CFG has 5 procedures, 24 locations, 3 error locations. Started 1 CEGAR loops. OverallTime: 874.3s, OverallIterations: 2, TraceHistogramMax: 0, PathProgramHistogramMax: 1, EmptinessCheckTime: 0.1s, AutomataDifference: 0.0s, DeadEndRemovalTime: 0.0s, HoareAnnotationTime: 0.0s, InitialAbstractionConstructionTime: 0.0s, HoareTripleCheckerStatistics: , PredicateUnifierStatistics: No data available, 0.0s BasicInterpolantAutomatonTime, BiggestAbstraction: size=0occurred in iteration=0, InterpolantAutomatonStates: 4, traceCheckStatistics: No data available, InterpolantConsolidationStatistics: No data available, PathInvariantsStatistics: No data available, 0/0 InterpolantCoveringCapability, TotalInterpolationStatistics: No data available, 0.0s DumpTime, AutomataMinimizationStatistics: No data available, HoareAnnotationStatistics: No data available, RefinementEngineStatistics: TRACE_CHECK: 0.0s SsaConstructionTime, 0.0s SatisfiabilityAnalysisTime, 0.3s InterpolantComputationTime, 11 NumberOfCodeBlocks, 11 NumberOfCodeBlocksAsserted, 1 NumberOfCheckSat, 10 ConstructedInterpolants, 0 QuantifiedInterpolants, 52 SizeOfPredicates, 0 NumberOfNonLiveVariables, 0 ConjunctsInSsa, 0 ConjunctsInUnsatCore, 1 InterpolantComputations, 1 PerfectInterpolantSequences, 0/0 InterpolantCoveringCapability, INVARIANT_SYNTHESIS: No data available, INTERPOLANT_CONSOLIDATION: No data available, ABSTRACT_INTERPRETATION: No data available, PDR: No data available, ACCELERATED_INTERPOLATION: No data available, SIFA: No data available, ReuseStatistics: No data available, ConditionalCommutativityCheckTime: 0.0s, ConditionalCommutativityIAIntegrations: 0, ConditionalCommutativityDFSRestarts: 0, ConditionalCommutativityImperfectProofs: 0 RESULT: Ultimate could not prove your program: Timeout Completed graceful shutdown