Merge 12965 via scriptthreads-27+knots

src/checkqueue.h

@@ -182,6 +182,7 @@ public:
     }
 
     bool HasThreads() const { return !m_worker_threads.empty(); }
+    size_t ThreadCount() const { return m_worker_threads.size(); }
 };
 
 /**

src/rpc/blockchain.cpp

@@ -1497,6 +1497,69 @@ static RPCHelpMan verifychain()
     };
 }
 
+static RPCHelpMan scriptthreadsinfo()
+{
+    return RPCHelpMan{"scriptthreadsinfo",
+                "\nShow information about the script verification threads.\n",
+                {},
+                RPCResult{
+                    RPCResult::Type::OBJ, "", "",
+                    {
+                        {RPCResult::Type::BOOL, "enabled", "true if script verification threads are enabled (see setscriptthreadsenabled)."},
+                        {RPCResult::Type::NUM, "num_script_check_threads", "The total number of script verification threads, when enabled."},
+                    },
+                },
+                RPCExamples{
+                    HelpExampleCli("scriptthreadsinfo", "")
+            + HelpExampleRpc("scriptthreadsinfo", "")
+                },
+        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
+{
+    ChainstateManager& chainman = EnsureAnyChainman(request.context);
+    UniValue ret(UniValue::VOBJ);
+    size_t thread_count{chainman.m_script_check_queue_enabled ? chainman.GetCheckQueue().ThreadCount() : 0};
+    ret.pushKV("enabled", (bool)thread_count);
+    ret.pushKV("num_script_check_threads", (int64_t)thread_count + 1);
+    return ret;
+},
+    };
+}
+
+static RPCHelpMan setscriptthreadsenabled()
+{
+    return RPCHelpMan{"setscriptthreadsenabled",
+                "\nDisable/enable script verification threads, thereby reducing CPU usage on multicore systems on demand.\n"
+                "Disabling script verification threads may result in a significant slow-down during synchronisation.\n"
+                "Has no effect on single core machines or if started with -par=<-<numcores>\n",
+                {
+                    {"state", RPCArg::Type::BOOL, RPCArg::Optional::NO, "false if script verification threads should be disabled (true for re-enabling)"},
+                },
+                RPCResult{RPCResult::Type::NONE, "", ""},
+                RPCExamples{
+                    HelpExampleCli("setscriptthreadsenabled", "false")
+            + HelpExampleRpc("setscriptthreadsenabled", "false")
+                },
+        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
+{
+    ChainstateManager& chainman = EnsureAnyChainman(request.context);
+    LOCK(cs_main);
+
+    const bool parallel_script_checks{request.params[0].get_bool()};
+    if (parallel_script_checks) {
+        if (!chainman.GetCheckQueue().HasThreads()) {
+            throw JSONRPCError(RPC_MISC_ERROR, "Script verification threads are disabled (single core machine or -par=<-<numcores>)");
+        }
+
+        chainman.m_script_check_queue_enabled = true;
+    } else {
+        chainman.m_script_check_queue_enabled = false;
+    }
+
+    return NullUniValue;
+},
+    };
+}
+
 static void SoftForkDescPushBack(const CBlockIndex* blockindex, UniValue& softforks, const ChainstateManager& chainman, Consensus::BuriedDeployment dep)
 {
     // For buried deployments.
@@ -3428,6 +3491,8 @@ void RegisterBlockchainRPCCommands(CRPCTable& t)
         {"blockchain", &setprunelock},
         {"blockchain", &pruneblockchain},
         {"blockchain", &verifychain},
+        {"blockchain", &scriptthreadsinfo},
+        {"blockchain", &setscriptthreadsenabled},
         {"blockchain", &preciousblock},
         {"blockchain", &scantxoutset},
         {"blockchain", &scanblocks},

src/rpc/client.cpp

@@ -313,6 +313,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "echojson", 9, "arg9" },
     { "rescanblockchain", 0, "start_height"},
     { "rescanblockchain", 1, "stop_height"},
+    { "setscriptthreadsenabled", 0, "state"},
     { "createwallet", 1, "disable_private_keys"},
     { "createwallet", 2, "blank"},
     { "createwallet", 4, "avoid_reuse"},

src/test/fuzz/rpc.cpp

@@ -169,11 +169,13 @@ const std::vector<std::string> RPC_COMMANDS_SAFE_FOR_FUZZING{
     "reconsiderblock",
     "scanblocks",
     "scantxoutset",
+    "scriptthreadsinfo",
     "sendmsgtopeer", // when no peers are connected, no p2p message is sent
     "sendrawtransaction",
     "setmocktime",
     "setnetworkactive",
     "setprunelock",
+    "setscriptthreadsenabled",
     "signmessagewithprivkey",
     "signrawtransactionwithkey",
     "submitblock",

src/validation.cpp

@@ -2196,7 +2196,7 @@ bool Chainstate::ConnectBlock(const CBlock& block, BlockValidationState& state,
 
     uint256 block_hash{block.GetHash()};
     assert(*pindex->phashBlock == block_hash);
-    const bool parallel_script_checks{m_chainman.GetCheckQueue().HasThreads()};
+    const bool parallel_script_checks{m_chainman.m_script_check_queue_enabled && m_chainman.GetCheckQueue().HasThreads()};
 
     const auto time_start{SteadyClock::now()};
     const CChainParams& params{m_chainman.GetParams()};

src/validation.h

@@ -1271,6 +1271,7 @@ public:
     //! nullopt.
     std::optional<int> GetSnapshotBaseHeight() const EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
+    bool m_script_check_queue_enabled{true};
     CCheckQueue<CScriptCheck>& GetCheckQueue() { return m_script_check_queue; }
 
     ~ChainstateManager();