Debugging param tuning (I think it runs now) (#8012)

* draft attempt at optimizing cube tree with resolvents. have not tested/ran yet * adding comments * fix bug about needing to bubble resolvent upwards to highest ancestor * fix bug where we need to cover the whole resolvent in the path when bubbling up * clean up comments * Bump actions/checkout from 4 to 5 (#7954) Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 5. - [Release notes](https://github.com/actions/checkout/releases) - [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md) - [Commits](https://github.com/actions/checkout/compare/v4...v5) --- updated-dependencies: - dependency-name: actions/checkout dependency-version: '5' dependency-type: direct:production update-type: version-update:semver-major ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> * close entire tree when sibling resolvent is empty * integrate asms directly into cube tree, remove separate tracking * try to fix bug about redundant resolutions, merging close and try_resolve_upwards into once function * separate the logic again to avoid mutual recursion * [WIP] Add a mutex to warning.cpp to ensure that warning messages from different threads don't interfere (#7963) * Initial plan * Add mutex to warning.cpp for thread safety Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> * Remove unused variable 'first' in mpz.cpp Removed unused variable 'first' from the function. * fixing the order Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * fixing the order Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * fix the order of parameter evaluation Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * remove AI slop Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com> * param order Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * param order Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * param order evaluation * parameter eval order * parameter evaluation order * param eval * param eval order * parameter eval order Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * parameter eval order Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * parameter eval order Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * parameter eval order Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * parameter eval order Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * parameter eval order Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * parameter eval order Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * Bump github/codeql-action from 3 to 4 (#7971) Bumps [github/codeql-action](https://github.com/github/codeql-action) from 3 to 4. - [Release notes](https://github.com/github/codeql-action/releases) - [Changelog](https://github.com/github/codeql-action/blob/main/CHANGELOG.md) - [Commits](https://github.com/github/codeql-action/compare/v3...v4) --- updated-dependencies: - dependency-name: github/codeql-action dependency-version: '4' dependency-type: direct:production update-type: version-update:semver-major ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> * Update Z3_mk_datatype_sort API to accept array of sort parameters and add Z3_mk_polymorphic_datatype (#7966) * Initial plan * Update Z3_mk_datatype_sort API to accept array of parameters Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> * Update language bindings for parametric datatype sort API - Python: Updated DatatypeSort() to accept optional params list - OCaml: Added mk_sort_ref_p/mk_sort_ref_ps for parametric datatypes - .NET: Added MkDatatypeSortRef() methods with optional params - Java: Added mkDatatypeSortRef() methods with optional params - All changes maintain backward compatibility Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> * Fix .NET build error - rename params to parameters The 'params' keyword is reserved in C#, causing compilation errors. Renamed parameter from 'params' to 'parameters' in MkDatatypeSortRef methods. Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> * Add unit test for parametric datatypes Added test_parametric_datatype.cpp to demonstrate polymorphic datatypes. The test creates two concrete instantiations of a generic pair concept: - pair_int_real with fields (first:Int, second:Real) - pair_real_int with fields (first:Real, second:Int) Then verifies that accessors work correctly and type checking is enforced. Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> * Implement polymorphic type variables support for parametric datatypes - Modified datatype_decl_plugin to allow type variables as parameters - Updated mk_datatype_decl to extract type variables from field sorts - Type variables are collected in order of first appearance - Revised unit test to use Z3_mk_type_variable for polymorphic datatypes - Test creates pair datatype with type variables alpha and beta - Successfully instantiates with concrete types (pair Int Real) and (pair Real Int) - Verifies accessor types match and equality terms are well-typed - All tests pass Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> * Add Z3_mk_polymorphic_datatype API and refactor datatype creation - Added new API Z3_mk_polymorphic_datatype to z3_api.h - Renamed static mk_datatype_decl to api_datatype_decl in api_datatype.cpp - Modified api_datatype_decl to accept explicit type parameters - Updated all callers to use renamed function - Added test_polymorphic_datatype_api demonstrating new API usage - Both tests pass successfully Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> * Remove type variable collection logic from constructors Removed the logic for collecting type variables from field sorts based on constructors. * Update comments on parameter handling in api_datatype.cpp Clarify usage of parameters in API documentation. * Fix OCaml build error - use list instead of array for mk_datatype_sort Changed mk_sort_ref to pass empty list [] instead of empty array [||]. Changed mk_sort_ref_p to pass params list directly instead of converting to array. Z3native.mk_datatype_sort expects a list, not an array. Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> * Add polymorphic datatype example to C++ examples Added polymorphic_datatype_example() demonstrating: - Creating type variables alpha and beta with Z3_mk_type_variable - Defining parametric Pair datatype with fields of type alpha and beta - Instantiating with concrete types (Pair Int Real) and (Pair Real Int) - Getting constructors and accessors from instantiated datatypes - Creating constants and expressions using the polymorphic types - Verifying type correctness with equality (= (first p1) (second p2)) Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> Co-authored-by: Nikolaj Bjorner <nbjorner@microsoft.com> * trim parametric datatype test Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com> * restore single cell Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * restore the method behavior Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * setting up python tuning experiment, not done * Add finite_set_value_factory for creating finite set values in model generation (#7981) * Initial plan * Add finite_set_value_factory implementation Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> * Remove unused dl_decl_plugin variable and include Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> * Update copyright and add TODOs in finite_set_value_factory Updated copyright information and added TODO comments for handling in finite_set_value_factory methods. * Update copyright information in finite_set_value_factory.h Updated copyright year from 2006 to 2025. * Implement finite_set_value_factory using array_util to create singleton sets Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> * Simplify empty set creation in finite_set_value_factory Refactor finite_set_value_factory to simplify empty set handling and remove array-specific logic. * Change family ID for finite_set_value_factory * Fix build error by restoring array_decl_plugin include and implementation Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> * Update finite_set_value_factory.h * Add SASSERT for finite set check in factory Added assertion to check if the sort is a finite set. * Rename member variable from m_util to u * Refactor finite_set_value_factory for value handling * Use register_value instead of direct set insertion Replaced direct insertion into set with register_value calls. * Update finite_set_value_factory.cpp --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> Co-authored-by: Nikolaj Bjorner <nbjorner@microsoft.com> * Revert "Add finite_set_value_factory for creating finite set values in model …" (#7985) This reverts commit 05ffc0a77b. * Update arith_rewriter.cpp fix memory leak introduced by update to ensure determinism * update pythonnn prototyping experiment, need to add a couple more things * add explicit constructors for nightly mac build failure Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com> * build fixes Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com> * fixes * fix some more things but now it hangs * change multithread to multiprocess seems to have resolved current deadlock * fix some bugs, it seems to run now * fix logic about checking clauses individually, and add proof prefix clause selection (naively) via the OnClause hook * disable manylinux until segfault is resolved Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com> * add the "noexcept" keyword to value_score=(value_score&&) declaration * expose a status flag for clauses but every single one is being coded as an assumption... * Add a fast-path to _coerce_exprs. (#7995) When the inputs are already the same sort, we can skip most of the coercion logic and just return. Currently, `_coerce_exprs` is by far the most expensive part of building up many common Z3 ASTs, so this fast-path is a substantial speedup for many use-cases. * Bump actions/setup-node from 5 to 6 (#7994) Bumps [actions/setup-node](https://github.com/actions/setup-node) from 5 to 6. - [Release notes](https://github.com/actions/setup-node/releases) - [Commits](https://github.com/actions/setup-node/compare/v5...v6) --- updated-dependencies: - dependency-name: actions/setup-node dependency-version: '6' dependency-type: direct:production update-type: version-update:semver-major ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> * Enabling Control Flow Guard (CFG) by default for MSVC on Windows, with options to disable CFG. (#7988) * Enabling Control Flow Guard by default for MSVC on Windows, with options to disable it. * Fix configuration error for non-MSVC compilers. * Reviewed and updated configuration for Python build and added comment for CFG. * try exponential delay in grobner Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * throttle grobner method more actively Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * enable always add all coeffs in nlsat Signed-off-by: Lev Nachmanson <levnach@hotmail.com> * initial parameter probe thread setup in C++ * more param tuning setup * setting up the param probe solvers and mutation generator * adding the learned clauses from the internalizer * fix some things for clause replay * score the param probes, but i can't figure out how to access the relevant solver statistics fields from the statistics obj * set up pattern to notify batch manager so worker threads can update their params according ly * add a getter for solver stats. it compiles but still everything is untested * bugfix * updates to param tuning * remove the getter for solver statistics since we're getting the vals directly from the context * merge * patch fix for default manager construction so it can be used to create the param tuning context without segfault * still debugging threading issues where we can't create nested param tuners or it spins infinitely. added flag for this. but now there is segfault on the probe_ctx.check() call * make param tuning singlethreaded to resolve segfault when spawning subprocesses ffor nested ctx checks --------- Signed-off-by: dependabot[bot] <support@github.com> Signed-off-by: Lev Nachmanson <levnach@hotmail.com> Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Copilot <198982749+Copilot@users.noreply.github.com> Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> Co-authored-by: Nikolaj Bjorner <nbjorner@microsoft.com> Co-authored-by: Lev Nachmanson <levnach@hotmail.com> Co-authored-by: Nelson Elhage <nelhage@nelhage.com> Co-authored-by: hwisungi <hwisungi@users.noreply.github.com>
2025-11-22 13:41:27 +00:00 · 2025-11-04 13:42:17 -08:00 · 2025-11-04 13:42:17 -08:00 · 2e74175467
commit 2e74175467
parent 863d0e3e5e
5 changed files with 78 additions and 36 deletions
--- a/src/smt/smt_context.cpp
+++ b/src/smt/smt_context.cpp
@ -3617,15 +3617,15 @@ namespace smt {
       \remark A logical context can only be configured at scope level 0,
       and before internalizing any formulas.
    */
-    lbool context::setup_and_check(bool reset_cancel) {
+    lbool context::setup_and_check(bool reset_cancel, bool enable_parallel_param_tuning) {
        if (!check_preamble(reset_cancel)) return l_undef;
        SASSERT(m_scope_lvl == 0);
        SASSERT(!m_setup.already_configured());
        setup_context(m_fparams.m_auto_config);

        if (m_fparams.m_threads > 1 && !m.has_trace_stream()) {
-            parallel p(*this);
            expr_ref_vector asms(m);
+            parallel p(*this, enable_parallel_param_tuning);
            return p(asms);
        }

@ -3685,14 +3685,15 @@ namespace smt {
        }
    }

-    lbool context::check(unsigned num_assumptions, expr * const * assumptions, bool reset_cancel) {
+    lbool context::check(unsigned num_assumptions, expr * const * assumptions, bool reset_cancel, bool enable_parallel_param_tuning) {
        if (!check_preamble(reset_cancel)) return l_undef;
        SASSERT(at_base_level());
        setup_context(false);
        search_completion sc(*this);
        if (m_fparams.m_threads > 1 && !m.has_trace_stream()) {            
            expr_ref_vector asms(m, num_assumptions, assumptions);
-            parallel p(*this);
+            IF_VERBOSE(1, verbose_stream() << "Starting parallel check with " << asms.size() << " assumptions and param tuning enabled: " << enable_parallel_param_tuning << "\n");
+            parallel p(*this, enable_parallel_param_tuning);
            return p(asms);
        }
        lbool r = l_undef;
--- a/src/smt/smt_context.h
+++ b/src/smt/smt_context.h
@ -132,6 +132,7 @@ namespace smt {
        unsigned                    m_par_index = 0;
        bool                        m_internalizing_assertions = false;
        lbool                       m_internal_completed = l_undef;
+        bool                        m_in_parallel = false;

        scoped_ptr<dependent_expr_simplifier> m_simplifier;
        scoped_ptr<base_dependent_expr_state> m_fmls;
@ -1689,7 +1690,7 @@ namespace smt {

        void pop(unsigned num_scopes);

-        lbool check(unsigned num_assumptions = 0, expr * const * assumptions = nullptr, bool reset_cancel = true);
+        lbool check(unsigned num_assumptions = 0, expr * const * assumptions = nullptr, bool reset_cancel = true, bool enable_parallel_param_tuning = true);

        lbool check(expr_ref_vector const& cube, vector<expr_ref_vector> const& clauses);

@ -1699,7 +1700,7 @@ namespace smt {

        lbool preferred_sat(expr_ref_vector const& asms, vector<expr_ref_vector>& cores);

-        lbool setup_and_check(bool reset_cancel = true);
+        lbool setup_and_check(bool reset_cancel = true, bool enable_parallel_param_tuning = true);

        void reduce_assertions();

--- a/src/smt/smt_internalizer.cpp
+++ b/src/smt/smt_internalizer.cpp
@ -990,7 +990,8 @@ namespace smt {

    
    void context::undo_mk_bool_var() {
-        SASSERT(!m_b_internalized_stack.empty());
+        SASSERT(!m_b_internalized_stack.empty(ue key per literal
+            m_lit_scores[lit.sign()][v] += 1.));
        m_stats.m_num_del_bool_var++;
        expr * n              = m_b_internalized_stack.back();
        unsigned n_id         = n->get_id();
--- a/src/smt/smt_parallel.cpp
+++ b/src/smt/smt_parallel.cpp
@ -66,13 +66,18 @@ namespace smt {
 namespace smt {

    lbool parallel::param_generator::run_prefix_step() {
-        IF_VERBOSE(1, verbose_stream() << " Param generator running prefix step\n");
+        if (m.limit().is_canceled())
+            return l_undef;
+        IF_VERBOSE(1, verbose_stream() << " PARAM TUNER running prefix step\n");
        ctx->get_fparams().m_max_conflicts = m_max_prefix_conflicts;
+        ctx->get_fparams().m_threads = 1;
+
        m_recorded_cubes.reset();
        ctx->m_recorded_cubes = &m_recorded_cubes;
        lbool r = l_undef;
        try {
-            r = ctx->check();
+            r = ctx->check(0, nullptr, true, false);
+            IF_VERBOSE(1, verbose_stream() << " PARAM TUNER: prefix step result " << r << "\n");
        } 
        catch (z3_error &err) {
            b.set_exception(err.error_code());
@ -93,8 +98,11 @@ namespace smt {
        bool found_better_params = false;

        for (unsigned i = 0; i <= N; ++i) {
-            IF_VERBOSE(1, verbose_stream() << " PARAM TUNER: replaying proof prefix in param probe context " << i << "\n");
+            if (m.limit().is_canceled())
+              return;

+            IF_VERBOSE(1, verbose_stream() << " PARAM TUNER: replaying proof prefix in param probe context " << i << "\n");
+            
            // copy prefix solver context to a new probe_ctx for next replay with candidate mutation
            smt_params smtp(m_p);
            scoped_ptr<context> probe_ctx = alloc(context, m, smtp, m_p);
@ -110,11 +118,16 @@ namespace smt {
            }

            probe_ctx->get_fparams().m_max_conflicts = conflict_budget;
+            probe_ctx->get_fparams().m_threads = 1;

            // replay the cube (negation of the clause)
+            IF_VERBOSE(1, verbose_stream() << " PARAM TUNER: begin replay of " << m_recorded_cubes.size() << " cubes\n");
            for (expr_ref_vector const& cube : m_recorded_cubes) {
-                lbool r = probe_ctx->check(cube.size(), cube.data());               
-                IF_VERBOSE(1, verbose_stream() << " PARAM TUNER " << i << ": cube replay result " << r << "\n");                
+                if (m.limit().is_canceled())
+                  return;
+                // the conflicts and decisions are cumulative over all cube replays inside the probe_ctx
+                lbool r = probe_ctx->check(cube.size(), cube.data(), true, false);               
+                IF_VERBOSE(2, verbose_stream() << " PARAM TUNER " << i << ": cube replay result " << r << "\n");                
            }
            unsigned conflicts = probe_ctx->m_stats.m_num_conflicts;
            unsigned decisions = probe_ctx->m_stats.m_num_decisions;
@ -130,10 +143,7 @@ namespace smt {
                best_score = score;
            }
        }
-        // NOTE: we either need to apply the best params found that are better than base line
-        // or, we have to implement a comparison operator for param_values (what would this do?)
-        // or, we update the param state every single time even if it hasn't changed (what would this do?)
-        // for now, I went with option 1
+        
        if (found_better_params) {
            m_param_state = best_param_state;
            auto p = apply_param_values(m_param_state);
@ -192,7 +202,8 @@ namespace smt {
            }
            std::get<unsigned_value>(param.second).value = new_value;
        }
-        IF_VERBOSE(0, 
+        IF_VERBOSE(1, 
+            verbose_stream() << "Mutating param: ";
            for (auto const &[name, val] : new_param_values) {
                if (std::holds_alternative<bool>(val)) {
                    verbose_stream() << name << " = " << std::get<bool>(val) << "\n";
@ -211,6 +222,9 @@ namespace smt {
        ctx->get_fparams().m_max_conflicts = m_max_prefix_conflicts;
        lbool r = run_prefix_step();

+        if (m.limit().is_canceled())
+            return;
+
        switch (r) {
            case l_undef: {
                replay_proof_prefixes();
@ -234,6 +248,11 @@ namespace smt {
        }
    }

+    void parallel::param_generator::cancel() {
+        IF_VERBOSE(1, verbose_stream() << " PARAM TUNER cancelling\n");
+        m.limit().cancel();
+    }
+
    void parallel::worker::run() {
        search_tree::node<cube_config> *node = nullptr;
        expr_ref_vector cube(m);
@ -255,7 +274,7 @@ namespace smt {

            lbool r = check_cube(cube);

-            if (!m.inc()) {
+            if (m.limit().is_canceled()) {
                b.set_exception("context cancelled");
                return;
            }
@ -320,7 +339,11 @@ namespace smt {
    }

    parallel::param_generator::param_generator(parallel& p)
-        : p(p), b(p.m_batch_manager), m_p(p.ctx.get_params()), m_l2g(m, p.ctx.m) {
+        : b(p.m_batch_manager), m_p(p.ctx.get_params()), m_l2g(m, p.ctx.m) {
+        // patch fix so that ctx = alloc(context, m, p.ctx.get_fparams(), m_p); doesn't crash due to some issue with default construction of m
+        ast_translation m_g2l(p.ctx.m, m);
+        m_g2l(p.ctx.m.mk_true());
+
        ctx = alloc(context, m, p.ctx.get_fparams(), m_p);
        context::copy(p.ctx, *ctx, true);
        // don't share initial units
@ -450,7 +473,7 @@ namespace smt {
        IF_VERBOSE(1, m_search_tree.display(verbose_stream() << bounded_pp_exprs(core) << "\n"););
        if (m_search_tree.is_closed()) {
            m_state = state::is_unsat;
-            cancel_workers();
+            cancel_background_threads();
        }
    }

@ -516,7 +539,7 @@ namespace smt {
                                       << bounded_pp_exprs(cube)
                                       << "with max_conflicts: " << ctx->get_fparams().m_max_conflicts << "\n";);
        try {
-            r = ctx->check(asms.size(), asms.data());
+            r = ctx->check(asms.size(), asms.data(), true, false);
        } catch (z3_error &err) {
            b.set_exception(err.error_code());
        } catch (z3_exception &ex) {
@ -561,7 +584,7 @@ namespace smt {
            return;
        m_state = state::is_sat;
        p.ctx.set_model(m.translate(l2g));
-        cancel_workers();
+        cancel_background_threads();
    }

    void parallel::batch_manager::set_unsat(ast_translation &l2g, expr_ref_vector const &unsat_core) {
@ -575,7 +598,7 @@ namespace smt {
        SASSERT(p.ctx.m_unsat_core.empty());
        for (expr *e : unsat_core)
            p.ctx.m_unsat_core.push_back(l2g(e));
-        cancel_workers();
+        cancel_background_threads();
    }

    void parallel::batch_manager::set_exception(unsigned error_code) {
@ -585,7 +608,7 @@ namespace smt {
            return;
        m_state = state::is_exception_code;
        m_exception_code = error_code;
-        cancel_workers();
+        cancel_background_threads();
    }

    void parallel::batch_manager::set_exception(std::string const &msg) {
@ -595,7 +618,7 @@ namespace smt {
            return;
        m_state = state::is_exception_msg;
        m_exception_msg = msg;
-        cancel_workers();
+        cancel_background_threads();
    }

    lbool parallel::batch_manager::get_result() const {
@ -675,6 +698,7 @@ namespace smt {

        m_batch_manager.initialize();
        m_workers.reset();
+        
        scoped_limits sl(m.limit());
        flet<unsigned> _nt(ctx.m_fparams.m_threads, 1);
        SASSERT(num_threads > 1);
@ -684,15 +708,16 @@ namespace smt {
        for (auto w : m_workers)
            sl.push_child(&(w->limit()));
        
-        sl.push_child(&(m_param_generator.limit()));
+        sl.push_child(&(m_param_generator->limit()));

        // Launch threads
-        vector<std::thread> threads(num_threads + 1); // +1 for parameter generator
-        for (unsigned i = 0; i < num_threads - 1; ++i) {
+        vector<std::thread> threads(m_enable_param_tuner ? num_threads + 1 : num_threads); // +1 for param generator
+        for (unsigned i = 0; i < num_threads; ++i) {
            threads[i] = std::thread([&, i]() { m_workers[i]->run(); });
        }
        // the final thread runs the parameter generator
-        threads[num_threads - 1] = std::thread([&]() { m_param_generator.protocol_iteration(); });
+        if (m_enable_param_tuner)
+            threads[num_threads] = std::thread([&]() { m_param_generator->protocol_iteration(); });

        // Wait for all threads to finish
        for (auto &th : threads)
--- a/src/smt/smt_parallel.h
+++ b/src/smt/smt_parallel.h
@ -36,6 +36,7 @@ namespace smt {
    class parallel {
        context& ctx;
        unsigned num_threads;
+        bool m_enable_param_tuner;

        struct shared_clause {
            unsigned source_worker_id;
@ -57,7 +58,6 @@ namespace smt {
                unsigned m_num_cubes = 0;
            };

-
            ast_manager& m;
            parallel& p;
            std::mutex mux;
@ -72,6 +72,11 @@ namespace smt {
            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

+            void cancel_background_threads() {
+                cancel_workers();
+                cancel_param_generator();
+            }
+
            // called from batch manager to cancel other workers if we've reached a verdict
            void cancel_workers() {
                IF_VERBOSE(1, verbose_stream() << "Canceling workers\n");
@ -79,6 +84,11 @@ namespace smt {
                    w->cancel();
            }

+            void cancel_param_generator() {
+                IF_VERBOSE(1, verbose_stream() << "Canceling param generator\n");
+                p.m_param_generator->cancel();
+            }
+
        public:
            batch_manager(ast_manager& m, parallel& p) : m(m), p(p), m_search_tree(expr_ref(m)) { }

@ -88,7 +98,10 @@ namespace smt {
            void set_sat(ast_translation& l2g, model& m);
            void set_exception(std::string const& msg);
            void set_exception(unsigned error_code);
-            void set_param_state(params_ref const& p) { m_param_state.copy(p); }
+            void set_param_state(params_ref const& p) { 
+              m_param_state.copy(p); 
+              IF_VERBOSE(1, verbose_stream() << "Batch manager updated param state\n");
+            }
            void get_param_state(params_ref &p);
            void collect_statistics(::statistics& st) const;            

@ -118,11 +131,9 @@ namespace smt {
            using param_value = std::variant<unsigned_value, bool>;
            using param_values = vector<std::pair<symbol, param_value>>;

-            parallel &p;
            batch_manager &b;
            ast_manager m;
            scoped_ptr<context> ctx;
-            ast_translation m_l2g;

            unsigned N = 4;  // number of prefix permutations to test (including current)
            unsigned m_max_prefix_conflicts = 1000;
@ -131,6 +142,7 @@ namespace smt {
            vector<expr_ref_vector> m_recorded_cubes;
            params_ref m_p;
            param_values m_param_state;
+            ast_translation m_l2g;

            params_ref apply_param_values(param_values const &pv);
            void init_param_state();
@ -141,6 +153,7 @@ namespace smt {
            lbool run_prefix_step();
            void protocol_iteration();
            void replay_proof_prefixes(unsigned max_conflicts_epsilon);
+            void cancel();

            reslimit &limit() {
                return m.limit();
@ -206,16 +219,17 @@ namespace smt {

        batch_manager m_batch_manager;
        scoped_ptr_vector<worker> m_workers;
-        param_generator m_param_generator;
+        scoped_ptr<param_generator> m_param_generator;

    public:
-        parallel(context& ctx) : 
+        parallel(context& ctx, bool enable_param_tuner = true) : 
            ctx(ctx),
            num_threads(std::min(
                (unsigned)std::thread::hardware_concurrency(),
                ctx.get_fparams().m_threads)),
+            m_enable_param_tuner(enable_param_tuner),
            m_batch_manager(ctx.m, *this),
-            m_param_generator(*this) {}
+            m_param_generator(enable_param_tuner ? alloc(param_generator, *this) : nullptr) {}

        lbool operator()(expr_ref_vector const& asms);
    };