merge

PARALLEL_PROJECT_NOTES.md

@@ -215,4 +215,80 @@ SMT parameters that could be tuned:
   seq.split_w_len (bool) (default: true)
 </pre>
 
+# Benchmark setup
 
+## Prepare benchmark data
+
+Data
+<pre>
+QF_LIA            - heavily skewed for selected benchmarks
+QF_NIA_small  
+
+Others we should try:
+
+Certora
+QF_ABV
+QF_UFBV
+QF_AUFBV (or whatever it is called)
+QF_UFLIA (might be too small)
+
+push more instances from smtlib.org benchmarks into z3-poly-testing/inputs or upload tgz files directly in setup.
+
+</pre>
+
+## Naming conventions and basic parameters
+
+The first rounds created a base-line where all features were turned off, then it created variants where one feature was turned off at a time.
+The data-point where all but one feature is turned off could tell us something if a feature has a chance of being useful in isolation.
+The following is a sample naming scheme for associated settings.
+
+<pre>
+threads-1
+-T:30 smt.threads=1 tactic.default_tactic=smt
+
+threads-4-none-unbounded
+-T:30 smt.threads=4 tactic.default_tactic=smt smt_parallel.never_cube=true smt_parallel.share_conflicts=false smt_parallel.share_units=false smt.threads.max_conflicts=4294967295
+
+threads-4-none
+-T:30 smt.threads=4 tactic.default_tactic=smt smt_parallel.never_cube=true smt_parallel.share_conflicts=false smt_parallel.share_units=false 
+
+threads-4-shareunits
+-T:30 smt.threads=4 tactic.default_tactic=smt smt_parallel.never_cube=true smt_parallel.share_conflicts=false smt_parallel.share_units=true 
+
+threads-4-cube-frugal
+-T:30 smt.threads=4 tactic.default_tactic=smt smt_parallel.never_cube=false smt_parallel.frugal_cube_only=true smt_parallel.share_conflicts=false smt_parallel.share_units=false
+
+threads-4-cube-frugal-shareconflicts
+-T:30 smt.threads=4 tactic.default_tactic=smt smt_parallel.never_cube=false smt_parallel.frugal_cube_only=true smt_parallel.share_conflicts=true smt_parallel.share_units=false 
+
+threads-4-shareunits-nonrelevant
+-T:30 smt.threads=4 tactic.default_tactic=smt smt_parallel.never_cube=true smt_parallel.share_conflicts=true smt_parallel.share_units=false smt_parallel.relevant_units_only=false 
+
+threads-4-cube
+-T:30 smt.threads=4 tactic.default_tactic=smt smt_parallel.never_cube=false smt_parallel.frugal_cube_only=false smt_parallel.share_conflicts=false smt_parallel.share_units=false 
+
+threads-4-cube-shareconflicts
+-T:30 smt.threads=4 tactic.default_tactic=smt smt_parallel.never_cube=false smt_parallel.frugal_cube_only=false smt_parallel.share_conflicts=true smt_parallel.share_units=false 
+
+</pre>
+
+Ideas for other knobs that can be tested
+
+<il>
+<li> Only cube on literals that exist in initial formula. Don't cube on literals created during search (such as by theory lemmas).
+<li> Only share units for literals that exist in the initial formula.
+<li> Vary the backoff scheme for <b>max_conflict_mul</b> from 1.5 to lower and higher.
+<li> Vary <b>smt.threads.max_conflicts</b>
+<li> Replace backoff scheme by a geometric scheme: add <b>conflict_inc</b> (a new parameter) every time and increment <b>conflict_inc</b>
+</il>
+
+<pre>
+  cube_initial_only (bool) (default: false)          only useful when never_cube=false
+  frugal_cube_only (bool) (default: false)           only useful when never_cube=false
+  max_conflict_mul (double) (default: 1.5)
+  never_cube (bool) (default: false)
+  relevant_units_only (bool) (default: true)         only useful when share_units=true
+  share_conflicts (bool) (default: true)             only useful when never_cube=false
+  share_units (bool) (default: true)
+  share_units_initial_only (bool) (default: false)   only useful when share_units=true
+</pre>

src/math/lp/lp_settings.cpp

@@ -41,4 +41,5 @@ void lp::lp_settings::updt_params(params_ref const& _p) {
     m_dio_ignore_big_nums = lp_p.dio_ignore_big_nums();
     m_dio_calls_period = lp_p.dio_calls_period();
     m_dio_run_gcd = lp_p.dio_run_gcd();
+    m_max_conflicts = p.max_conflicts();
 }

src/math/lp/lp_settings.h

@@ -137,6 +137,7 @@ struct statistics {
     unsigned m_bounds_tightening_conflicts = 0;
     unsigned m_bounds_tightenings = 0;
     unsigned m_nla_throttled_lemmas = 0;
+
     ::statistics m_st = {};
 
     void reset() {
@@ -221,11 +222,13 @@ public:
     unsigned     percent_of_entering_to_check = 5; // we try to find a profitable column in a percentage of the columns
     bool         use_scaling = true;
     unsigned     max_number_of_iterations_with_no_improvements = 2000000;
- double       time_limit; // the maximum time limit of the total run time in seconds
+    double       time_limit; // the maximum time limit of the total run time in seconds
     // end of dual section
     bool                   m_bound_propagation = true;
     bool                   presolve_with_double_solver_for_lar = true;
     simplex_strategy_enum  m_simplex_strategy;
+
+    unsigned         m_max_conflicts = 0;
     
     int              report_frequency = 1000;
     bool             print_statistics = false;

src/math/lp/nla_core.cpp

@@ -38,7 +38,7 @@ core::core(lp::lar_solver& s, params_ref const& p, reslimit & lim) :
     m_grobner(this),
     m_emons(m_evars),
     m_use_nra_model(false),
-    m_nra(s, m_nra_lim, *this),
+    m_nra(s, m_nra_lim, *this, p),
     m_throttle(lra.trail(), 
 	lra.settings().stats()) {
      m_nlsat_delay_bound = lp_settings().nlsat_delay();
@@ -1561,6 +1561,9 @@ lbool core::check() {
     if (no_effect() && params().arith_nl_nra()) {
         scoped_limits sl(m_reslim);
         sl.push_child(&m_nra_lim);
+        params_ref p;
+        p.set_uint("max_conflicts", lp_settings().m_max_conflicts);
+        m_nra.updt_params(p);
         ret = m_nra.check();
         lp_settings().stats().m_nra_calls++;
     }
@@ -1595,7 +1598,7 @@ lbool core::bounded_nlsat() {
         scoped_rlimit sr(m_nra_lim, 100000);
         ret = m_nra.check();
     }
-    p.set_uint("max_conflicts", UINT_MAX);           
+    p.set_uint("max_conflicts", lp_settings().m_max_conflicts);           
     m_nra.updt_params(p);
     lp_settings().stats().m_nra_calls++;
     if (ret == l_undef) 

src/params/smt_parallel_params.pyg

@@ -6,5 +6,8 @@ def_module_params('smt_parallel',
                         ('share_conflicts', BOOL, True, 'share conflicts'),
                         ('never_cube', BOOL, False, 'never cube'),
                         ('frugal_cube_only', BOOL, False, 'only apply frugal cube strategy'),
-                        ('relevant_units_only', BOOL, False, 'only share relvant units')
+                        ('relevant_units_only', BOOL, True, 'only share relvant units'),
+                        ('max_conflict_mul', DOUBLE, 1.5, 'increment multiplier for max-conflicts'),
+                        ('share_units_initial_only', BOOL, False, 'share only initial Boolean atoms as units'),
+                        ('cube_initial_only', BOOL, False, 'cube only on initial Boolean atoms')
               ))

src/smt/smt_parallel.cpp

@@ -39,48 +39,50 @@ namespace smt {
 #include <thread>
 #include <cassert>
 
+#define LOG_WORKER(lvl, s) IF_VERBOSE(lvl, verbose_stream() << "Worker " << id << s)
+
 namespace smt {
 
     void parallel::worker::run() {
-        ast_translation g2l(p.ctx.m, m); // global to local context -- MUST USE p.ctx.m, not ctx->m, AS GLOBAL MANAGER!!!
-        ast_translation l2g(m, p.ctx.m); // local to global context
         while (m.inc()) { // inc: increase the limit and check if it is canceled, vs m.limit().is_canceled() is readonly. the .limit() is also not necessary (m.inc() etc provides a convenience wrapper)
             vector<expr_ref_vector> cubes;
-            b.get_cubes(g2l, cubes);
+            b.get_cubes(m_g2l, cubes);
             if (cubes.empty())
                 return;
-            collect_shared_clauses(g2l);
+            collect_shared_clauses(m_g2l);
             for (auto& cube : cubes) {
                 if (!m.inc()) {
                     b.set_exception("context cancelled");
                     return;
                 }
-                IF_VERBOSE(1, verbose_stream() << "Worker " << id << " checking cube: " << mk_bounded_pp(mk_and(cube), m, 3) << "\n");
+                LOG_WORKER(1, " checking cube: " << mk_bounded_pp(mk_and(cube), m, 3) << " max-conflicts " << m_config.m_threads_max_conflicts << "\n");
                 lbool r = check_cube(cube);
                 if (m.limit().is_canceled()) {
-                    IF_VERBOSE(1, verbose_stream() << "Worker " << id << " context cancelled\n");
+                    LOG_WORKER(1, " context cancelled\n");
                     return;           
                 }
                 switch (r) {
                     case l_undef: {
                         if (m.limit().is_canceled())
                             break;
-                        IF_VERBOSE(1, verbose_stream() << "Worker " << id << " found undef cube\n");
+                        LOG_WORKER(1, " found undef cube\n");
                         // return unprocessed cubes to the batch manager
                         // add a split literal to the batch manager.
                         // optionally process other cubes and delay sending back unprocessed cubes to batch manager.
-                        vector<expr_ref_vector> returned_cubes;
-                        returned_cubes.push_back(cube);
-                        auto split_atoms = get_split_atoms();
-                        b.return_cubes(l2g, returned_cubes, split_atoms);
+                        if (!m_config.m_never_cube) {
+                            vector<expr_ref_vector> returned_cubes;
+                            returned_cubes.push_back(cube);
+                            auto split_atoms = get_split_atoms();
+                            b.return_cubes(m_l2g, returned_cubes, split_atoms);
+                        }
                         update_max_thread_conflicts();
                         break;
                     }
                     case l_true: {
-                        IF_VERBOSE(1, verbose_stream() << "Worker " << id << " found sat cube\n");
+                        LOG_WORKER(1, " found sat cube\n");
                         model_ref mdl;
                         ctx->get_model(mdl);
-                        b.set_sat(l2g, *mdl);
+                        b.set_sat(m_l2g, *mdl);
                         return;
                     }
                     case l_false: {
@@ -89,42 +91,58 @@ namespace smt {
                         // share with batch manager.
                         // process next cube.
                         expr_ref_vector const& unsat_core = ctx->unsat_core();
-                        IF_VERBOSE(1, verbose_stream() << "unsat core: " << unsat_core << "\n");
+                        LOG_WORKER(2, " unsat core:\n"; for (auto c : unsat_core) verbose_stream() << mk_bounded_pp(c, m, 3) << "\n");
                         // If the unsat core only contains assumptions, 
                         // unsatisfiability does not depend on the current cube and the entire problem is unsat.
                         if (all_of(unsat_core, [&](expr* e) { return asms.contains(e); })) {
-                            IF_VERBOSE(1, verbose_stream() << "Worker " << id << " determined formula unsat\n");
-                            b.set_unsat(l2g, unsat_core);
+                            LOG_WORKER(1, " determined formula unsat\n");
+                            b.set_unsat(m_l2g, unsat_core);
                             return;
                         }
                         for (expr* e : unsat_core)
                             if (asms.contains(e))
-                                b.report_assumption_used(l2g, e); // report assumptions used in unsat core, so they can be used in final core
+                                b.report_assumption_used(m_l2g, e); // report assumptions used in unsat core, so they can be used in final core
 
-                        IF_VERBOSE(1, verbose_stream() << "Worker " << id << " found unsat cube\n");
-                        if (smt_parallel_params(p.ctx.m_params).share_conflicts())
-                            b.collect_clause(l2g, id, mk_not(mk_and(unsat_core)));
+                        LOG_WORKER(1, " found unsat cube\n");
+                        if (m_config.m_share_conflicts)
+                            b.collect_clause(m_l2g, id, mk_not(mk_and(unsat_core)));
                         break;
                     }
                 }     
             }
-            if (smt_parallel_params(p.ctx.m_params).share_units())
-                share_units(l2g);
+            if (m_config.m_share_units)
+                share_units(m_l2g);
         }
     }
 
-    parallel::worker::worker(unsigned id, parallel& p, expr_ref_vector const& _asms): id(id), p(p), b(p.m_batch_manager), m_smt_params(p.ctx.get_fparams()), asms(m) {
-        ast_translation g2l(p.ctx.m, m);
+    parallel::worker::worker(unsigned id, parallel& p, expr_ref_vector const& _asms): 
+        id(id), p(p), b(p.m_batch_manager), m_smt_params(p.ctx.get_fparams()), asms(m),
+        m_g2l(p.ctx.m, m),
+        m_l2g(m, p.ctx.m) {
         for (auto e : _asms) 
-            asms.push_back(g2l(e));
-        IF_VERBOSE(1, verbose_stream() << "Worker " << id << " created with " << asms.size() << " assumptions\n");        
+            asms.push_back(m_g2l(e));
+        LOG_WORKER(1, " created with " << asms.size() << " assumptions\n");        
         m_smt_params.m_preprocess = false;
         ctx = alloc(context, m, m_smt_params, p.ctx.get_params());
         context::copy(p.ctx, *ctx, true);
         ctx->set_random_seed(id + m_smt_params.m_random_seed);
 
-        m_max_thread_conflicts = ctx->get_fparams().m_threads_max_conflicts;
-        m_max_conflicts = ctx->get_fparams().m_max_conflicts;
+        smt_parallel_params pp(p.ctx.m_params);
+        m_config.m_threads_max_conflicts = ctx->get_fparams().m_threads_max_conflicts;
+        m_config.m_max_conflicts = ctx->get_fparams().m_max_conflicts;
+        m_config.m_relevant_units_only = pp.relevant_units_only();
+        m_config.m_never_cube = pp.never_cube();
+        m_config.m_share_conflicts = pp.share_conflicts();
+        m_config.m_share_units = pp.share_units();
+        m_config.m_share_units_initial_only = pp.share_units_initial_only();
+        m_config.m_cube_initial_only = pp.cube_initial_only();
+        m_config.m_max_conflict_mul = pp.max_conflict_mul();
+
+        // don't share initial units
+        ctx->pop_to_base_lvl();
+        m_num_shared_units = ctx->assigned_literals().size();
+
+        m_num_initial_atoms = ctx->get_num_bool_vars();
     }
 
     void parallel::worker::share_units(ast_translation& l2g) {
@@ -133,15 +151,18 @@ namespace smt {
         unsigned sz = ctx->assigned_literals().size();
         for (unsigned j = m_num_shared_units; j < sz; ++j) {  // iterate only over new literals since last sync
             literal lit = ctx->assigned_literals()[j];
-            if (!ctx->is_relevant(lit.var()) && smt_parallel_params(p.ctx.m_params).relevant_units_only()) {
-                // IF_VERBOSE(0, verbose_stream() << "non-relevant literal " << lit << "\n");
+            if (!ctx->is_relevant(lit.var()) && m_config.m_relevant_units_only) 
                 continue;
+
+            if (m_config.m_share_units_initial_only && lit.var() >= m_num_initial_atoms) {
+                LOG_WORKER(2, " Skipping non-initial unit: " << lit.var() << "\n");
+                continue; // skip non-iniial atoms if configured to do so
             }
+            
             expr_ref e(ctx->bool_var2expr(lit.var()), ctx->m); // turn literal into a Boolean expression
-            if (m.is_and(e) || m.is_or(e)) {
-                //IF_VERBOSE(0, verbose_stream() << "skip Boolean\n");                
+            if (m.is_and(e) || m.is_or(e))             
                 continue;
-            }
+            
 
             if (lit.sign()) 
                 e = m.mk_not(e); // negate if literal is negative
@@ -150,6 +171,40 @@ namespace smt {
         m_num_shared_units = sz;
     }
 
+    void parallel::batch_manager::init_parameters_state() {
+        auto& smt_params = p.ctx.get_fparams();
+        std::function<std::function<void(void)>(unsigned&)> inc = [](unsigned& v) { return [&]() -> void { ++v; }; };
+        std::function<std::function<void(void)>(unsigned&)> dec = [](unsigned& v) { return [&]() -> void { if (v > 0) --v; }; };       
+        std::function<std::function<void(void)>(bool&)> incb = [](bool& v) { return [&]() -> void { v = true; }; };
+        std::function<std::function<void(void)>(bool&)> decb = [](bool& v) { return [&]() -> void { v = false; }; };
+        std::function<parameter_state(unsigned&)> unsigned_parameter = [&](unsigned& p) -> parameter_state {
+            return { { { p , 1.0}},
+                       { { 1.0, inc(p) }, { 1.0, dec(p) }} 
+                   };
+        };
+        std::function<parameter_state(bool&)> bool_parameter = [&](bool& p) -> parameter_state {
+            return { { { p , 1.0}},
+                       { { 1.0, incb(p) }, { 1.0, decb(p) }}
+            };
+        };
+
+        parameter_state s1 = unsigned_parameter(smt_params.m_arith_branch_cut_ratio);
+        parameter_state s2 = bool_parameter(smt_params.m_arith_eager_eq_axioms);    
+
+        //  arith.enable_hnf(bool) (default: true)
+        //  arith.greatest_error_pivot(bool) (default: false)
+        //  arith.int_eq_branch(bool) (default: false)
+        //  arith.min(bool) (default: false)
+        //  arith.nl.branching(bool) (default: true)
+        //  arith.nl.cross_nested(bool) (default: true)
+        //  arith.nl.delay(unsigned int) (default: 10)
+        //  arith.nl.expensive_patching(bool) (default: false)
+        //  arith.nl.expp(bool) (default: false)
+        //  arith.nl.gr_q(unsigned int) (default: 10)
+        //  arith.nl.grobner(bool) (default: true)
+        //  arith.nl.grobner_cnfl_to_report(unsigned int) (default: 1) };
+    }
+
     void parallel::batch_manager::collect_clause(ast_translation& l2g, unsigned source_worker_id, expr* clause) {
         std::scoped_lock lock(mux);
         expr* g_clause = l2g(clause);
@@ -166,7 +221,7 @@ namespace smt {
         for (expr* e : new_clauses) {
             expr_ref local_clause(e, g2l.to()); // e was already translated to the local context in the batch manager!!
             ctx->assert_expr(local_clause); // assert the clause in the local context
-            IF_VERBOSE(2, verbose_stream() << "Worker " << id << " asserting shared clause: " << mk_bounded_pp(local_clause, m, 3) << "\n");
+            LOG_WORKER(2, " asserting shared clause: " << mk_bounded_pp(local_clause, m, 3) << "\n");
         }
     }
 
@@ -188,7 +243,7 @@ namespace smt {
             asms.push_back(atom);                
         lbool r = l_undef;
 
-        ctx->get_fparams().m_max_conflicts = std::min(m_max_thread_conflicts, m_max_conflicts);
+        ctx->get_fparams().m_max_conflicts = std::min(m_config.m_threads_max_conflicts, m_config.m_max_conflicts);
         try {
             r = ctx->check(asms.size(), asms.data());
         }
@@ -202,7 +257,7 @@ namespace smt {
             b.set_exception("unknown exception");
         }
         asms.shrink(asms.size() - cube.size());
-        IF_VERBOSE(1, verbose_stream() << "Worker " << id << " DONE checking cube " << r << "\n";);
+        LOG_WORKER(1, " DONE checking cube " << r << "\n";);
         return r;
     }
 
@@ -354,8 +409,7 @@ namespace smt {
 
     // currenly, the code just implements the greedy strategy
     void parallel::batch_manager::return_cubes(ast_translation& l2g, vector<expr_ref_vector>const& C_worker, expr_ref_vector const& A_worker) {
-        if (smt_parallel_params(p.ctx.m_params).never_cube())
-            return; // portfolio only
+        SASSERT(!smt_parallel_params(p.ctx.m_params).never_cube());
 
         auto atom_in_cube = [&](expr_ref_vector const& cube, expr* atom) {
             return any_of(cube, [&](expr* e) { return e == atom || (m.is_not(e, e) && e == atom); });
@@ -364,7 +418,9 @@ namespace smt {
         auto add_split_atom = [&](expr* atom, unsigned start) {
             unsigned stop = m_cubes.size();
             for (unsigned i = start; i < stop; ++i) {
-                m_cubes.push_back(m_cubes[i]);
+                // copy the last cube so that expanding m_cubes doesn't invalidate reference.
+                auto cube = m_cubes[i];
+                m_cubes.push_back(cube);
                 m_cubes.back().push_back(m.mk_not(atom));
                 m_cubes[i].push_back(atom);
             }
@@ -440,9 +496,15 @@ namespace smt {
 
         expr_ref_vector top_lits(m);
         for (const auto& node: candidates) {
+
             if (ctx->get_assignment(node.key) != l_undef) 
                 continue;
 
+            if (m_config.m_cube_initial_only && node.key >= m_num_initial_atoms) {
+                LOG_WORKER(2, " Skipping non-initial atom from cube: " << node.key << "\n");
+                continue; // skip non-initial atoms if configured to do so
+            }
+
             expr* e = ctx->bool_var2expr(node.key);
             if (!e) 
                 continue;
@@ -451,7 +513,7 @@ namespace smt {
             if (top_lits.size() >= k) 
                 break;
         }
-        IF_VERBOSE(2, verbose_stream() << "top literals " << top_lits << " head size " << ctx->m_pq_scores.size() << " num vars " << ctx->get_num_bool_vars() << "\n");
+        IF_VERBOSE(3, verbose_stream() << "top literals " << top_lits << " head size " << ctx->m_pq_scores.size() << " num vars " << ctx->get_num_bool_vars() << "\n");
         return top_lits;
     }
 

src/smt/smt_parallel.h

@@ -11,7 +11,7 @@ Abstract:
 
 Author:
 
-    nbjorner 2020-01-31
+    Ilana 2025
 
 Revision History:
 
@@ -32,6 +32,11 @@ namespace smt {
             expr_ref clause;
         };
 
+        struct parameter_state {
+            std::vector<std::pair<unsigned, double>> m_value_scores; // bounded number of values with scores.
+            std::vector<std::pair<double, std::function<void(void)>>> m_weighted_moves; // possible moves weighted by how well they did
+        };
+
         class batch_manager {        
             enum state {
                 is_running,
@@ -52,6 +57,7 @@ namespace smt {
             std::string m_exception_msg;
             vector<shared_clause> shared_clause_trail; // store all shared clauses with worker IDs
             obj_hashtable<expr> shared_clause_set; // for duplicate filtering on per-thread clause expressions
+            vector<parameter_state> m_parameters_state;
 
             // called from batch manager to cancel other workers if we've reached a verdict
             void cancel_workers() {
@@ -60,6 +66,8 @@ namespace smt {
                     w->cancel();
             }
 
+            void init_parameters_state();
+
         public:
             batch_manager(ast_manager& m, parallel& p) : m(m), p(p), m_split_atoms(m) { }
 
@@ -89,21 +97,33 @@ namespace smt {
         };
 
         class worker {
+            struct config {
+                unsigned m_threads_max_conflicts = 1000;
+                unsigned m_max_conflicts = 10000000;
+                bool m_relevant_units_only = true;
+                bool m_never_cube = false;
+                bool m_share_conflicts = true;
+                bool m_share_units = true;
+                double m_max_conflict_mul = 1.5;
+                bool m_share_units_initial_only = false;
+                bool m_cube_initial_only = false;
+            };
             unsigned id; // unique identifier for the worker
             parallel& p;
             batch_manager& b;
             ast_manager m;
             expr_ref_vector asms;
             smt_params m_smt_params;
+            config m_config;
             scoped_ptr<context> ctx;
-            unsigned m_max_conflicts; // the global budget for all work this worker can do across cubes in the current run. THIS GETS SET IN THE CPP FILE
-            unsigned m_max_thread_conflicts; // the per-cube limit for how many conflicts the worker can spend on a single cube before timing out on it and moving on. THIS GETS SET IN THE CPP FILE
+            ast_translation m_g2l, m_l2g;
             unsigned m_num_shared_units = 0;
+            unsigned m_num_initial_atoms = 0;
             unsigned m_shared_clause_limit = 0; // remembers the index into shared_clause_trail marking the boundary between "old" and "new" clauses to share
             void share_units(ast_translation& l2g);
             lbool check_cube(expr_ref_vector const& cube);
             void update_max_thread_conflicts() {
-                m_max_thread_conflicts *= 2;
+                m_config.m_threads_max_conflicts = (unsigned)(m_config.m_max_conflict_mul * m_config.m_threads_max_conflicts);
             } // allow for backoff scheme of conflicts within the thread for cube timeouts.
         public:
             worker(unsigned id, parallel& p, expr_ref_vector const& _asms);
@@ -116,7 +136,6 @@ namespace smt {
                 m.limit().cancel();
             }
             void collect_statistics(::statistics& st) const {
-                IF_VERBOSE(1, verbose_stream() << "Collecting statistics for worker " << id << "\n");
                 ctx->collect_statistics(st);
             }
             reslimit& limit() {

src/smt/theory_lra.cpp

@@ -1427,6 +1427,8 @@ public:
     void init_search_eh() {
         m_arith_eq_adapter.init_search_eh();
         m_num_conflicts = 0;
+        if (m_solver)   
+           lp().settings().m_max_conflicts = ctx().get_fparams().m_max_conflicts;
     }
 
     bool can_get_value(theory_var v) const {