java -Xmx8000000000 -Xss4m -jar ./plugins/org.eclipse.equinox.launcher_1.3.100.v20150511-1540.jar -data @noDefault -ultimatedata ./data -tc ../../../trunk/examples/toolchains/Sifa.xml -i ../../../trunk/examples/programs/20170319-ConjunctivePathPrograms/pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl -------------------------------------------------------------------------------- This is Ultimate 0.1.24-e6f8464 [2019-08-06 14:22:51,050 INFO L177 SettingsManager]: Resetting all preferences to default values... [2019-08-06 14:22:51,052 INFO L181 SettingsManager]: Resetting UltimateCore preferences to default values [2019-08-06 14:22:51,064 INFO L184 SettingsManager]: Ultimate Commandline Interface provides no preferences, ignoring... [2019-08-06 14:22:51,064 INFO L181 SettingsManager]: Resetting Boogie Preprocessor preferences to default values [2019-08-06 14:22:51,065 INFO L181 SettingsManager]: Resetting Boogie Procedure Inliner preferences to default values [2019-08-06 14:22:51,066 INFO L181 SettingsManager]: Resetting Abstract Interpretation preferences to default values [2019-08-06 14:22:51,068 INFO L181 SettingsManager]: Resetting LassoRanker preferences to default values [2019-08-06 14:22:51,070 INFO L181 SettingsManager]: Resetting Reaching Definitions preferences to default values [2019-08-06 14:22:51,071 INFO L181 SettingsManager]: Resetting SyntaxChecker preferences to default values [2019-08-06 14:22:51,072 INFO L181 SettingsManager]: Resetting Symbolic Interpretation preferences to default values [2019-08-06 14:22:51,073 INFO L184 SettingsManager]: Büchi Program Product provides no preferences, ignoring... [2019-08-06 14:22:51,073 INFO L181 SettingsManager]: Resetting LTL2Aut preferences to default values [2019-08-06 14:22:51,074 INFO L181 SettingsManager]: Resetting PEA to Boogie preferences to default values [2019-08-06 14:22:51,076 INFO L181 SettingsManager]: Resetting BlockEncodingV2 preferences to default values [2019-08-06 14:22:51,077 INFO L181 SettingsManager]: Resetting ChcToBoogie preferences to default values [2019-08-06 14:22:51,078 INFO L181 SettingsManager]: Resetting AutomataScriptInterpreter preferences to default values [2019-08-06 14:22:51,079 INFO L181 SettingsManager]: Resetting BuchiAutomizer preferences to default values [2019-08-06 14:22:51,084 INFO L181 SettingsManager]: Resetting CACSL2BoogieTranslator preferences to default values [2019-08-06 14:22:51,086 INFO L181 SettingsManager]: Resetting CodeCheck preferences to default values [2019-08-06 14:22:51,090 INFO L181 SettingsManager]: Resetting InvariantSynthesis preferences to default values [2019-08-06 14:22:51,091 INFO L181 SettingsManager]: Resetting RCFGBuilder preferences to default values [2019-08-06 14:22:51,092 INFO L181 SettingsManager]: Resetting Referee preferences to default values [2019-08-06 14:22:51,093 INFO L181 SettingsManager]: Resetting TraceAbstraction preferences to default values [2019-08-06 14:22:51,095 INFO L184 SettingsManager]: TraceAbstractionConcurrent provides no preferences, ignoring... [2019-08-06 14:22:51,096 INFO L184 SettingsManager]: TraceAbstractionWithAFAs provides no preferences, ignoring... [2019-08-06 14:22:51,096 INFO L181 SettingsManager]: Resetting TreeAutomizer preferences to default values [2019-08-06 14:22:51,097 INFO L181 SettingsManager]: Resetting IcfgToChc preferences to default values [2019-08-06 14:22:51,097 INFO L181 SettingsManager]: Resetting IcfgTransformer preferences to default values [2019-08-06 14:22:51,098 INFO L184 SettingsManager]: ReqToTest provides no preferences, ignoring... [2019-08-06 14:22:51,098 INFO L181 SettingsManager]: Resetting Boogie Printer preferences to default values [2019-08-06 14:22:51,099 INFO L181 SettingsManager]: Resetting ChcSmtPrinter preferences to default values [2019-08-06 14:22:51,100 INFO L181 SettingsManager]: Resetting ReqPrinter preferences to default values [2019-08-06 14:22:51,101 INFO L181 SettingsManager]: Resetting Witness Printer preferences to default values [2019-08-06 14:22:51,102 INFO L184 SettingsManager]: Boogie PL CUP Parser provides no preferences, ignoring... [2019-08-06 14:22:51,102 INFO L181 SettingsManager]: Resetting CDTParser preferences to default values [2019-08-06 14:22:51,103 INFO L184 SettingsManager]: AutomataScriptParser provides no preferences, ignoring... [2019-08-06 14:22:51,103 INFO L184 SettingsManager]: ReqParser provides no preferences, ignoring... [2019-08-06 14:22:51,103 INFO L181 SettingsManager]: Resetting SmtParser preferences to default values [2019-08-06 14:22:51,104 INFO L181 SettingsManager]: Resetting Witness Parser preferences to default values [2019-08-06 14:22:51,105 INFO L188 SettingsManager]: Finished resetting all preferences to default values... [2019-08-06 14:22:51,147 INFO L81 nceAwareModelManager]: Repository-Root is: /tmp [2019-08-06 14:22:51,163 INFO L258 ainManager$Toolchain]: [Toolchain 1]: Applicable parser(s) successfully (re)initialized [2019-08-06 14:22:51,167 INFO L214 ainManager$Toolchain]: [Toolchain 1]: Toolchain selected. [2019-08-06 14:22:51,169 INFO L271 PluginConnector]: Initializing Boogie PL CUP Parser... [2019-08-06 14:22:51,170 INFO L275 PluginConnector]: Boogie PL CUP Parser initialized [2019-08-06 14:22:51,171 INFO L428 ainManager$Toolchain]: [Toolchain 1]: Parsing single file: /storage/repos/ultimate/releaseScripts/default/UAutomizer-linux/../../../trunk/examples/programs/20170319-ConjunctivePathPrograms/pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl [2019-08-06 14:22:51,171 INFO L110 BoogieParser]: Parsing: '/storage/repos/ultimate/releaseScripts/default/UAutomizer-linux/../../../trunk/examples/programs/20170319-ConjunctivePathPrograms/pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl' [2019-08-06 14:22:51,234 INFO L296 ainManager$Toolchain]: ####################### [Toolchain 1] ####################### [2019-08-06 14:22:51,236 INFO L131 ToolchainWalker]: Walking toolchain with 3 elements. [2019-08-06 14:22:51,236 INFO L113 PluginConnector]: ------------------------Boogie Preprocessor---------------------------- [2019-08-06 14:22:51,236 INFO L271 PluginConnector]: Initializing Boogie Preprocessor... [2019-08-06 14:22:51,236 INFO L275 PluginConnector]: Boogie Preprocessor initialized [2019-08-06 14:22:51,260 INFO L185 PluginConnector]: Executing the observer EnsureBoogieModelObserver from plugin Boogie Preprocessor for "pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 02:22:51" (1/1) ... [2019-08-06 14:22:51,262 INFO L185 PluginConnector]: Executing the observer TypeChecker from plugin Boogie Preprocessor for "pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 02:22:51" (1/1) ... [2019-08-06 14:22:51,271 INFO L185 PluginConnector]: Executing the observer ConstExpander from plugin Boogie Preprocessor for "pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 02:22:51" (1/1) ... [2019-08-06 14:22:51,271 INFO L185 PluginConnector]: Executing the observer StructExpander from plugin Boogie Preprocessor for "pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 02:22:51" (1/1) ... [2019-08-06 14:22:51,281 INFO L185 PluginConnector]: Executing the observer UnstructureCode from plugin Boogie Preprocessor for "pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 02:22:51" (1/1) ... [2019-08-06 14:22:51,287 INFO L185 PluginConnector]: Executing the observer FunctionInliner from plugin Boogie Preprocessor for "pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 02:22:51" (1/1) ... [2019-08-06 14:22:51,289 INFO L185 PluginConnector]: Executing the observer BoogieSymbolTableConstructor from plugin Boogie Preprocessor for "pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 02:22:51" (1/1) ... [2019-08-06 14:22:51,295 INFO L132 PluginConnector]: ------------------------ END Boogie Preprocessor---------------------------- [2019-08-06 14:22:51,300 INFO L113 PluginConnector]: ------------------------RCFGBuilder---------------------------- [2019-08-06 14:22:51,300 INFO L271 PluginConnector]: Initializing RCFGBuilder... [2019-08-06 14:22:51,300 INFO L275 PluginConnector]: RCFGBuilder initialized [2019-08-06 14:22:51,301 INFO L185 PluginConnector]: Executing the observer RCFGBuilderObserver from plugin RCFGBuilder for "pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 02:22:51" (1/1) ... No working directory specified, using /storage/repos/ultimate/releaseScripts/default/UAutomizer-linux/z3 Starting monitored process 1 with z3 SMTLIB2_COMPLIANT=true -memory:1024 -smt2 -in -t:12000 (exit command is (exit), workingDir is null) Waiting until toolchain timeout for monitored process 1 with z3 SMTLIB2_COMPLIANT=true -memory:1024 -smt2 -in -t:12000 [2019-08-06 14:22:51,375 INFO L124 BoogieDeclarations]: Specification and implementation of procedure ULTIMATE.start given in one single declaration [2019-08-06 14:22:51,375 INFO L130 BoogieDeclarations]: Found specification of procedure ULTIMATE.start [2019-08-06 14:22:51,375 INFO L138 BoogieDeclarations]: Found implementation of procedure ULTIMATE.start [2019-08-06 14:22:52,366 INFO L278 CfgBuilder]: Using the 1 location(s) as analysis (start of procedure ULTIMATE.start) [2019-08-06 14:22:52,366 INFO L283 CfgBuilder]: Removed 0 assume(true) statements. [2019-08-06 14:22:52,367 INFO L202 PluginConnector]: Adding new model pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl de.uni_freiburg.informatik.ultimate.plugins.generator.rcfgbuilder CFG 06.08 02:22:52 BoogieIcfgContainer [2019-08-06 14:22:52,367 INFO L132 PluginConnector]: ------------------------ END RCFGBuilder---------------------------- [2019-08-06 14:22:52,368 INFO L113 PluginConnector]: ------------------------Symbolic Interpretation---------------------------- [2019-08-06 14:22:52,368 INFO L271 PluginConnector]: Initializing Symbolic Interpretation... [2019-08-06 14:22:52,368 INFO L275 PluginConnector]: Symbolic Interpretation initialized [2019-08-06 14:22:52,369 INFO L185 PluginConnector]: Executing the observer SymbolicInterpretationObserver from plugin Symbolic Interpretation for "pals_lcr.3.ufo.UNBOUNDED.pals.c_14.bplTransformedIcfg_BEv2_29.bpl de.uni_freiburg.informatik.ultimate.plugins.generator.rcfgbuilder CFG 06.08 02:22:52" (1/1) ... [2019-08-06 14:22:52,381 INFO L148 IcfgInterpreter]: Started Sifa with 1 locations of interest [2019-08-06 14:22:52,384 INFO L155 IcfgInterpreter]: Building call graph [2019-08-06 14:22:52,390 INFO L160 IcfgInterpreter]: Initial procedures are [ULTIMATE.start] [2019-08-06 14:22:52,408 INFO L165 IcfgInterpreter]: Starting interpretation [2019-08-06 14:22:52,410 INFO L185 IcfgInterpreter]: Interpreting procedure ULTIMATE.start with input of size 1 [2019-08-06 14:22:52,498 INFO L169 IcfgInterpreter]: Interpretation finished [2019-08-06 14:22:52,498 INFO L177 IcfgInterpreter]: Final predicates for locations of interest are: [2019-08-06 14:22:52,502 INFO L179 IcfgInterpreter]: Location ULTIMATE.startErr0ASSERT_VIOLATIONASSERT has predicate 12#(and (<= 0 (+ ~id3 128)) (< ~send2 256) (not (= ~id2 ~id1)) (<= 0 (+ |ULTIMATE.start_init_#res| 2147483648)) (<= ~send2 127) (= ULTIMATE.start_node2_~m2~15 ~nomsg) (= ~p2_old ~nomsg) (<= 0 ~send3) (= 0 ULTIMATE.start_assert_~arg) (<= 0 (+ ~id1 128)) (= |ULTIMATE.start_init_#res| ULTIMATE.start_init_~tmp~29) (<= 0 ~id3) (<= 0 ~id1) (= ULTIMATE.start_init_~tmp~29 1) (<= ~id1 127) (= ~send2 ~id2) (<= 0 (+ ~st1 128)) (= ULTIMATE.start_main_~c1~73 |ULTIMATE.start_check_#res|) (not (= ~nomsg ~send2)) (< ~send3 256) (<= 0 ~send2) (or (and (= 0 ULTIMATE.start_main_~c1~73) (= |ULTIMATE.start_assert_#in~arg| 0)) (and (= |ULTIMATE.start_assert_#in~arg| 1) (not (= 0 ULTIMATE.start_main_~c1~73)))) (= |ULTIMATE.start_assert_#in~arg| ULTIMATE.start_assert_~arg) (= ~p2_new ~nomsg) (= ~p3_new ~nomsg) (= ~send3 ~id3) (<= 0 (+ ~send1 128)) (= 0 ~st1) (exists ((v_~p3_old_24 Int) (v_ULTIMATE.start_assert_~arg_18 Int) (|v_ULTIMATE.start_node1_#t~ite0_9| Int) (|v_ULTIMATE.start_node1_#t~ite0_12| Int) (v_~mode1_16 Int) (v_ULTIMATE.start_node1_~m1~7_15 Int) (v_~r1_30 Int) (v_ULTIMATE.start_check_~tmp~63_26 Int)) (and (or (and (= ~mode1 1) (= ~send3 v_~p3_old_24) (= ~r1 v_~r1_30) (<= 512 v_~mode1_16) (<= 0 ~p1_old) (= ULTIMATE.start_node1_~m1~7 ~nomsg) (<= ~p1_old 127) (= ~p1_old ~send1) (= (mod v_~mode1_16 256) 0) (not (= ~nomsg ~send1)) (< ~p1_old 256)) (and (< v_~mode1_16 256) (not (= 0 v_~mode1_16)) (= ULTIMATE.start_node1_~m1~7 ~nomsg) (<= 0 v_~r1_30) (not (= 255 v_~r1_30)) (< v_~r1_30 256) (= ~p1_old ~nomsg) (= |v_ULTIMATE.start_node1_#t~ite0_9| |ULTIMATE.start_node1_#t~ite0|) (= (+ v_~r1_30 1) ~r1) (= ~nomsg v_~p3_old_24) (= ULTIMATE.start_node1_~m1~7 ~send3) (<= 0 v_~mode1_16) (= ~mode1 0))) (or (and (< v_~r1_30 3) (= v_ULTIMATE.start_check_~tmp~63_26 1) (<= 0 v_~r1_30)) (and (not (< v_~r1_30 3)) (not (= (+ ~st3 ~st2 ~st1) 1)) (= v_ULTIMATE.start_check_~tmp~63_26 0) (< v_~r1_30 256))) (or (and (= 0 v_ULTIMATE.start_assert_~arg_18) (= v_ULTIMATE.start_check_~tmp~63_26 0)) (and (not (= v_ULTIMATE.start_check_~tmp~63_26 0)) (= 1 v_ULTIMATE.start_assert_~arg_18))) (not (= 0 v_ULTIMATE.start_assert_~arg_18)) (<= 0 (+ v_ULTIMATE.start_check_~tmp~63_26 2147483648)) (<= 0 v_ULTIMATE.start_assert_~arg_18) (<= v_ULTIMATE.start_check_~tmp~63_26 2147483647) (< v_ULTIMATE.start_assert_~arg_18 256) (or (and (= (+ ~st3 ~st2 ~st1) 0) (<= 0 v_~r1_30) (not (<= 3 v_~r1_30))) (and (<= 3 v_~r1_30) (< v_~r1_30 256))) (exists ((v_~p3_old_24 Int) (|v_ULTIMATE.start_node1_#t~ite0_9| Int) (v_~mode1_15 Int)) (and (or (and (< v_~mode1_15 256) (= |v_ULTIMATE.start_node1_#t~ite0_9| |v_ULTIMATE.start_node1_#t~ite0_12|) (= ~nomsg v_ULTIMATE.start_node1_~m1~7_15) (= 1 v_~r1_30) (not (= 0 v_~mode1_15)) (= ~nomsg v_~p3_old_24) (<= 0 v_~mode1_15) (= ULTIMATE.start_node2_~m2~15 ~nomsg) (= 0 v_~mode1_16)) (and (<= ULTIMATE.start_node2_~m2~15 127) (= ~nomsg v_ULTIMATE.start_node1_~m1~7_15) (<= 512 v_~mode1_15) (= ~nomsg v_~p3_old_24) (= 1 v_~mode1_16) (= 0 v_~r1_30) (< ULTIMATE.start_node2_~m2~15 256) (= ULTIMATE.start_node2_~m2~15 ~send1) (not (= ~nomsg ~send1)) (<= 0 ULTIMATE.start_node2_~m2~15) (= 0 (mod v_~mode1_15 256)))) (<= 512 v_~mode1_15) (= 0 (mod v_~mode1_15 256)))))) (<= |ULTIMATE.start_init_#res| 2147483647) (= 0 ~st2) (not (= ~id3 ~id2)) (or (and (= 0 ULTIMATE.start_check_~tmp~63) (< ~r1 256) (not (= (+ ~st3 ~st2 ~st1) 1)) (not (< ~r1 3))) (and (= 1 ULTIMATE.start_check_~tmp~63) (< ~r1 3) (<= 0 ~r1))) (<= ~st2 127) (<= 0 (+ ~send2 128)) (<= ~send3 127) (<= 0 (+ ~st3 128)) (not (= ~nomsg ~send3)) (<= 0 (+ ULTIMATE.start_main_~c1~73 2147483648)) (= ~p3_old ~nomsg) (<= ~st3 127) (or (and (= (+ ~st3 ~st2 ~st1) 0) (not (<= 3 ~r1)) (<= 0 ~r1)) (and (<= 3 ~r1) (< ~r1 256))) (= ~mode3 0) (= ~p1_new ~nomsg) (<= 0 (+ ~id2 128)) (<= ~send1 127) (<= 0 (+ ~send3 128)) (<= ~id2 127) (<= 0 ~id2) (= 0 ULTIMATE.start_main_~i2~73) (= ~mode2 0) (= 0 ~st3) (<= ~st1 127) (<= ~id3 127) (= ~send1 ~id1) (<= (+ ~st3 ~st2 ~st1) 1) (not (= ~id3 ~id1)) (= ~send2 ULTIMATE.start_node3_~m3~22) (<= ULTIMATE.start_main_~c1~73 2147483647) (= ~nomsg (- 1)) (<= 0 (+ ~st2 128)) (= ~nomsg ULTIMATE.start_node3_~m3~22) (= ULTIMATE.start_check_~tmp~63 |ULTIMATE.start_check_#res|) (not (= |ULTIMATE.start_init_#res| 0))) [2019-08-06 14:22:52,503 WARN L88 terpretationObserver]: Some locations of interest might be reachable, see reported results. [2019-08-06 14:22:52,510 INFO L132 PluginConnector]: ------------------------ END Symbolic Interpretation---------------------------- [2019-08-06 14:22:52,513 INFO L168 Benchmark]: Toolchain (without parser) took 1276.54 ms. Allocated memory was 140.0 MB in the beginning and 178.3 MB in the end (delta: 38.3 MB). Free memory was 106.4 MB in the beginning and 146.1 MB in the end (delta: -39.6 MB). Peak memory consumption was 52.3 MB. Max. memory is 7.1 GB. [2019-08-06 14:22:52,515 INFO L168 Benchmark]: Boogie PL CUP Parser took 0.25 ms. Allocated memory is still 140.0 MB. Free memory was 108.3 MB in the beginning and 108.1 MB in the end (delta: 209.8 kB). Peak memory consumption was 209.8 kB. Max. memory is 7.1 GB. [2019-08-06 14:22:52,516 INFO L168 Benchmark]: Boogie Preprocessor took 59.86 ms. Allocated memory is still 140.0 MB. Free memory was 106.4 MB in the beginning and 104.0 MB in the end (delta: 2.4 MB). Peak memory consumption was 2.4 MB. Max. memory is 7.1 GB. [2019-08-06 14:22:52,517 INFO L168 Benchmark]: RCFGBuilder took 1068.12 ms. Allocated memory is still 140.0 MB. Free memory was 104.0 MB in the beginning and 62.2 MB in the end (delta: 41.8 MB). Peak memory consumption was 41.8 MB. Max. memory is 7.1 GB. [2019-08-06 14:22:52,519 INFO L168 Benchmark]: Symbolic Interpretation took 142.32 ms. Allocated memory was 140.0 MB in the beginning and 178.3 MB in the end (delta: 38.3 MB). Free memory was 62.2 MB in the beginning and 146.1 MB in the end (delta: -83.8 MB). Peak memory consumption was 8.1 MB. Max. memory is 7.1 GB. [2019-08-06 14:22:52,523 INFO L335 ainManager$Toolchain]: ####################### End [Toolchain 1] ####################### --- Results --- * Results from de.uni_freiburg.informatik.ultimate.plugins.symbolicinterpretation: - UnprovableResult [Line: 304]: Unable to prove that assertion always holds Unable to prove that assertion always holds Reason: Interpreter reached this location of interest. Location might be reachable.. Possible FailurePath: * Results from de.uni_freiburg.informatik.ultimate.core: - StatisticsResult: Toolchain Benchmarks Benchmark results are: * Boogie PL CUP Parser took 0.25 ms. Allocated memory is still 140.0 MB. Free memory was 108.3 MB in the beginning and 108.1 MB in the end (delta: 209.8 kB). Peak memory consumption was 209.8 kB. Max. memory is 7.1 GB. * Boogie Preprocessor took 59.86 ms. Allocated memory is still 140.0 MB. Free memory was 106.4 MB in the beginning and 104.0 MB in the end (delta: 2.4 MB). Peak memory consumption was 2.4 MB. Max. memory is 7.1 GB. * RCFGBuilder took 1068.12 ms. Allocated memory is still 140.0 MB. Free memory was 104.0 MB in the beginning and 62.2 MB in the end (delta: 41.8 MB). Peak memory consumption was 41.8 MB. Max. memory is 7.1 GB. * Symbolic Interpretation took 142.32 ms. Allocated memory was 140.0 MB in the beginning and 178.3 MB in the end (delta: 38.3 MB). Free memory was 62.2 MB in the beginning and 146.1 MB in the end (delta: -83.8 MB). Peak memory consumption was 8.1 MB. Max. memory is 7.1 GB. RESULT: Ultimate could not prove your program: unable to determine feasibility of some traces Received shutdown request...