Limit default number of farming threads

crates/subspace-farmer/src/bin/subspace-farmer/commands/farm.rs

@@ -46,6 +46,8 @@ use tracing::{debug, error, info, info_span, warn};
 use zeroize::Zeroizing;
 
 const RECORDS_ROOTS_CACHE_SIZE: NonZeroUsize = NonZeroUsize::new(1_000_000).expect("Not zero; qed");
+/// It doesn't make a lot of sense to have a huge number of farming threads, 32 is plenty
+const MAX_DEFAULT_FARMING_THREADS: usize = 32;
 
 fn should_farm_during_initial_plotting() -> bool {
     let total_cpu_cores = all_cpu_cores()
@@ -128,7 +130,8 @@ pub(crate) struct FarmingArgs {
     farm_during_initial_plotting: bool,
     /// Size of PER FARM thread pool used for farming (mostly for blocking I/O, but also for some
     /// compute-intensive operations during proving), defaults to number of logical CPUs
-    /// available on UMA system and number of logical CPUs in first NUMA node on NUMA system
+    /// available on UMA system and number of logical CPUs in first NUMA node on NUMA system, but
+    /// not more than 32 threads
     #[arg(long)]
     farming_thread_pool_size: Option<NonZeroUsize>,
     /// Size of one thread pool used for plotting, defaults to number of logical CPUs available
@@ -507,7 +510,11 @@ where
             .zip(replotting_thread_pool_core_indices),
     )?;
     let farming_thread_pool_size = farming_thread_pool_size
-        .map(|farming_thread_pool_size| farming_thread_pool_size.get())
+        .map(|farming_thread_pool_size| {
+            farming_thread_pool_size
+                .get()
+                .min(MAX_DEFAULT_FARMING_THREADS)
+        })
         .unwrap_or_else(recommended_number_of_farming_threads);
 
     let all_cpu_cores = all_cpu_cores();