diff --git a/auron-core/src/main/java/org/apache/auron/configuration/AuronConfiguration.java b/auron-core/src/main/java/org/apache/auron/configuration/AuronConfiguration.java
index 3cd06d26f..6f22e2b69 100644
--- a/auron-core/src/main/java/org/apache/auron/configuration/AuronConfiguration.java
+++ b/auron-core/src/main/java/org/apache/auron/configuration/AuronConfiguration.java
@@ -43,9 +43,11 @@ public abstract class AuronConfiguration {
             .withKey("auron.tokio.worker.threads.per.cpu")
             .withCategory("Runtime Configuration")
             .withDescription(
-                    "Number of Tokio worker threads to create per CPU core (spark.task.cpus). Set to 0 for automatic detection "
-                            + "based on available CPU cores. This setting controls the thread pool size for Tokio-based asynchronous operations.")
-            .withDefaultValue(0);
+                    "Number of Tokio worker threads to create per CPU core (spark.task.cpus). Each task creates its own "
+                            + "Tokio runtime, so the default of 1 sizes it to the task's CPU allocation. Set to 0 to use "
+                            + "all available CPU cores of the host for every task, which can create a very large number "
+                            + "of threads on many-core machines.")
+            .withDefaultValue(1);
 
     public static final ConfigOption<Integer> SUGGESTED_BATCH_MEM_SIZE = new ConfigOption<>(Integer.class)
             .withKey("auron.suggested.batch.memSize")
diff --git a/native-engine/auron/src/rt.rs b/native-engine/auron/src/rt.rs
index 932ae3136..4a8dad86c 100644
--- a/native-engine/auron/src/rt.rs
+++ b/native-engine/auron/src/rt.rs
@@ -105,8 +105,8 @@ impl NativeExecutionRuntime {
         );
 
         let num_worker_threads = {
-            let worker_threads_per_cpu = TOKIO_WORKER_THREADS_PER_CPU.value().unwrap_or(0);
-            let task_cpus = TASK_CPUS.value().unwrap_or(0);
+            let worker_threads_per_cpu = TOKIO_WORKER_THREADS_PER_CPU.value().unwrap_or(1);
+            let task_cpus = TASK_CPUS.value().unwrap_or(1);
             worker_threads_per_cpu * task_cpus
         };