decrease default tracing permits

crates/node-core/src/args/rpc_server_args.rs

@@ -148,8 +148,8 @@ pub struct RpcServerArgs {
     pub rpc_max_connections: MaxU32,
 
     /// Maximum number of concurrent tracing requests.
-    #[arg(long, value_name = "COUNT", default_value_t = constants::DEFAULT_MAX_TRACING_REQUESTS)]
-    pub rpc_max_tracing_requests: u32,
+    #[arg(long, value_name = "COUNT", default_value_t = constants::default_max_tracing_requests())]
+    pub rpc_max_tracing_requests: usize,
 
     /// Maximum number of blocks that could be scanned per filter request. (0 = entire chain)
     #[arg(long, value_name = "COUNT", default_value_t = ZeroAsNoneU64::new(constants::DEFAULT_MAX_BLOCKS_PER_FILTER))]
@@ -499,7 +499,7 @@ impl Default for RpcServerArgs {
             rpc_max_response_size: RPC_DEFAULT_MAX_RESPONSE_SIZE_MB.into(),
             rpc_max_subscriptions_per_connection: RPC_DEFAULT_MAX_SUBS_PER_CONN.into(),
             rpc_max_connections: RPC_DEFAULT_MAX_CONNECTIONS.into(),
-            rpc_max_tracing_requests: constants::DEFAULT_MAX_TRACING_REQUESTS,
+            rpc_max_tracing_requests: constants::default_max_tracing_requests(),
             rpc_max_blocks_per_filter: constants::DEFAULT_MAX_BLOCKS_PER_FILTER.into(),
             rpc_max_logs_per_response: (constants::DEFAULT_MAX_LOGS_PER_RESPONSE as u64).into(),
             rpc_gas_cap: RPC_DEFAULT_GAS_CAP.into(),

crates/rpc/rpc-builder/src/constants.rs

@@ -3,6 +3,7 @@ pub use reth_rpc::eth::gas_oracle::{
     DEFAULT_GAS_PRICE_BLOCKS, DEFAULT_GAS_PRICE_PERCENTILE, DEFAULT_IGNORE_GAS_PRICE,
     DEFAULT_MAX_GAS_PRICE,
 };
+use std::cmp::max;
 
 /// The default port for the http server
 pub const DEFAULT_HTTP_RPC_PORT: u16 = 8545;
@@ -19,8 +20,16 @@ pub const DEFAULT_MAX_BLOCKS_PER_FILTER: u64 = 100_000;
 /// The default maximum of logs in a single response.
 pub const DEFAULT_MAX_LOGS_PER_RESPONSE: usize = 20_000;
 
-/// The default maximum number of concurrently executed tracing calls
-pub const DEFAULT_MAX_TRACING_REQUESTS: u32 = 25;
+/// The default maximum number tracing requests we're allowing concurrently.
+/// Tracing is mostly CPU bound so we're limiting the number of concurrent requests to something
+/// lower that the number of cores, in order to minimize the impact on the rest of the system.
+pub fn default_max_tracing_requests() -> usize {
+    // We reserve 2 cores for the rest of the system
+    const RESERVED: usize = 2;
+
+    std::thread::available_parallelism()
+        .map_or(25, |cpus| max(cpus.get().saturating_sub(RESERVED), RESERVED))
+}
 
 /// The default IPC endpoint
 #[cfg(windows)]

crates/rpc/rpc-builder/src/eth.rs

@@ -1,5 +1,5 @@
 use crate::constants::{
-    DEFAULT_MAX_BLOCKS_PER_FILTER, DEFAULT_MAX_LOGS_PER_RESPONSE, DEFAULT_MAX_TRACING_REQUESTS,
+    default_max_tracing_requests, DEFAULT_MAX_BLOCKS_PER_FILTER, DEFAULT_MAX_LOGS_PER_RESPONSE,
 };
 use reth_rpc::{
     eth::{
@@ -35,7 +35,7 @@ pub struct EthConfig {
     /// Settings for the gas price oracle
     pub gas_oracle: GasPriceOracleConfig,
     /// The maximum number of tracing calls that can be executed in concurrently.
-    pub max_tracing_requests: u32,
+    pub max_tracing_requests: usize,
     /// Maximum number of blocks that could be scanned per filter request in `eth_getLogs` calls.
     pub max_blocks_per_filter: u64,
     /// Maximum number of logs that can be returned in a single response in `eth_getLogs` calls.
@@ -69,7 +69,7 @@ impl Default for EthConfig {
         Self {
             cache: EthStateCacheConfig::default(),
             gas_oracle: GasPriceOracleConfig::default(),
-            max_tracing_requests: DEFAULT_MAX_TRACING_REQUESTS,
+            max_tracing_requests: default_max_tracing_requests(),
             max_blocks_per_filter: DEFAULT_MAX_BLOCKS_PER_FILTER,
             max_logs_per_response: DEFAULT_MAX_LOGS_PER_RESPONSE,
             rpc_gas_cap: RPC_DEFAULT_GAS_CAP.into(),
@@ -93,7 +93,7 @@ impl EthConfig {
     }
 
     /// Configures the maximum number of tracing requests
-    pub fn max_tracing_requests(mut self, max_requests: u32) -> Self {
+    pub fn max_tracing_requests(mut self, max_requests: usize) -> Self {
         self.max_tracing_requests = max_requests;
         self
     }

crates/tasks/src/pool.rs

@@ -24,8 +24,8 @@ pub struct BlockingTaskGuard(Arc<Semaphore>);
 impl BlockingTaskGuard {
     /// Create a new `BlockingTaskGuard` with the given maximum number of blocking tasks in
     /// parallel.
-    pub fn new(max_blocking_tasks: u32) -> Self {
-        Self(Arc::new(Semaphore::new(max_blocking_tasks as usize)))
+    pub fn new(max_blocking_tasks: usize) -> Self {
+        Self(Arc::new(Semaphore::new(max_blocking_tasks)))
     }
 
     /// See also [Semaphore::acquire_owned]

examples/custom-inspector/src/main.rs

@@ -3,7 +3,7 @@
 //! Run with
 //!
 //! ```not_rust
-//! cargo run --release -p custom-inspector --node --http --ws --recipients 0x....,0x....
+//! cargo run --release -p custom-inspector -- node --http --ws --recipients 0x....,0x....
 //! ```
 //!
 //! If no recipients are specified, all transactions will be inspected.