apache · andygrove · Apr 8, 2025 · Apr 6, 2025 · Apr 6, 2025 · Apr 6, 2025
diff --git a/common/src/main/java/org/apache/comet/parquet/Native.java b/common/src/main/java/org/apache/comet/parquet/Native.java
@@ -257,9 +257,7 @@ public static native long initRecordBatchReader(
       byte[] requiredSchema,
       byte[] dataSchema,
       String sessionTimezone,
-      int batchSize,
-      int workerThreads,
-      int blockingThreads);
+      int batchSize);
 
   // arrow native version of read batch
   /**

diff --git a/common/src/main/java/org/apache/comet/parquet/NativeBatchReader.java b/common/src/main/java/org/apache/comet/parquet/NativeBatchReader.java
@@ -357,16 +357,6 @@ public void init() throws URISyntaxException, IOException {
         conf.getInt(
             CometConf.COMET_BATCH_SIZE().key(),
             (Integer) CometConf.COMET_BATCH_SIZE().defaultValue().get());
-    int workerThreads =
-        conf.getInt(
-            CometConf.COMET_WORKER_THREADS().key(),
-            (Integer) CometConf.COMET_WORKER_THREADS().defaultValue().get());
-    ;
-    int blockingThreads =
-        conf.getInt(
-            CometConf.COMET_BLOCKING_THREADS().key(),
-            (Integer) CometConf.COMET_BLOCKING_THREADS().defaultValue().get());
-    ;
     this.handle =
         Native.initRecordBatchReader(
             filePath,
@@ -377,9 +367,7 @@ public void init() throws URISyntaxException, IOException {
             serializedRequestedArrowSchema,
             serializedDataArrowSchema,
             timeZoneId,
-            batchSize,
-            workerThreads,
-            blockingThreads);
+            batchSize);
     isInitialized = true;
   }
 

diff --git a/common/src/main/scala/org/apache/comet/CometConf.scala b/common/src/main/scala/org/apache/comet/CometConf.scala
@@ -457,22 +457,6 @@ object CometConf extends ShimCometConf {
       .booleanConf
       .createWithDefault(false)
 
-  val COMET_WORKER_THREADS: ConfigEntry[Int] =
-    conf("spark.comet.workerThreads")
-      .internal()
-      .doc("The number of worker threads used for Comet native execution. " +
-        "By default, this config is 4.")
-      .intConf
-      .createWithDefault(4)
-
-  val COMET_BLOCKING_THREADS: ConfigEntry[Int] =
-    conf("spark.comet.blockingThreads")
-      .internal()
-      .doc("The number of blocking threads used for Comet native execution. " +
-        "By default, this config is 10.")
-      .intConf
-      .createWithDefault(10)
-
   val COMET_BATCH_SIZE: ConfigEntry[Int] = conf("spark.comet.batchSize")
     .doc("The columnar batch size, i.e., the maximum number of rows that a batch can contain.")
     .intConf

diff --git a/docs/source/user-guide/tuning.md b/docs/source/user-guide/tuning.md
@@ -21,6 +21,15 @@ under the License.
 
 Comet provides some tuning options to help you get the best performance from your queries.
 
+## Configuring Tokio Runtime
+
+Comet uses a global tokio runtime per executor process using tokio's defaults of one worker thread per core and a 
+maximum of 512 blocking threads. These values can be overridden using the environment variables `COMET_WORKER_THREADS`
+and `COMET_MAX_BLOCKING_THREADS`.
+
+DataFusion currently has a known issue when merging spill files in sort operators where the process can deadlock if 
+there are more spill files than `COMET_MAX_BLOCKING_THREADS` ([tracking issue](https://github.com/apache/datafusion/issues/15323)).
+
 ## Memory Tuning
 
 It is necessary to specify how much memory Comet can use in addition to memory already allocated to Spark. In some

diff --git a/native/core/src/execution/jni_api.rs b/native/core/src/execution/jni_api.rs
@@ -71,6 +71,29 @@ use crate::execution::spark_plan::SparkPlan;
 use log::info;
 use once_cell::sync::{Lazy, OnceCell};
 
+static TOKIO_RUNTIME: Lazy<Runtime> = Lazy::new(|| {
+    let mut builder = tokio::runtime::Builder::new_multi_thread();
+    if let Some(n) = parse_usize_env_var("COMET_WORKER_THREADS") {
+        builder.worker_threads(n);
+    }
+    if let Some(n) = parse_usize_env_var("COMET_MAX_BLOCKING_THREADS") {
+        builder.max_blocking_threads(n);
+    }
+    builder
+        .enable_all()
+        .build()
+        .expect("Failed to create Tokio runtime")
+});
+
+fn parse_usize_env_var(name: &str) -> Option<usize> {
+    std::env::var_os(name).and_then(|n| n.to_str().and_then(|s| s.parse::<usize>().ok()))
+}
+
+/// Function to get a handle to the global Tokio runtime
+pub fn get_runtime() -> &'static Runtime {
+    &TOKIO_RUNTIME
+}
+
 /// Comet native execution context. Kept alive across JNI calls.
 struct ExecutionContext {
     /// The id of the execution context.
@@ -89,8 +112,6 @@ struct ExecutionContext {
     pub input_sources: Vec<Arc<GlobalRef>>,
     /// The record batch stream to pull results from
     pub stream: Option<SendableRecordBatchStream>,
-    /// The Tokio runtime used for async.
-    pub runtime: Runtime,
     /// Native metrics
     pub metrics: Arc<GlobalRef>,
     // The interval in milliseconds to update metrics
@@ -177,8 +198,6 @@ pub unsafe extern "system" fn Java_org_apache_comet_Native_createPlan(
     task_attempt_id: jlong,
     debug_native: jboolean,
     explain_native: jboolean,
-    worker_threads: jint,
-    blocking_threads: jint,
 ) -> jlong {
     try_unwrap_or_throw(&e, |mut env| {
         // Init JVM classes
@@ -192,13 +211,6 @@ pub unsafe extern "system" fn Java_org_apache_comet_Native_createPlan(
         // Deserialize query plan
         let spark_plan = serde::deserialize_op(bytes.as_slice())?;
 
-        // Use multi-threaded tokio runtime to prevent blocking spawned tasks if any
-        let runtime = tokio::runtime::Builder::new_multi_thread()
-            .worker_threads(worker_threads as usize)
-            .max_blocking_threads(blocking_threads as usize)
-            .enable_all()
-            .build()?;
-
         let metrics = Arc::new(jni_new_global_ref!(env, metrics_node)?);
 
         // Get the global references of input sources
@@ -258,7 +270,6 @@ pub unsafe extern "system" fn Java_org_apache_comet_Native_createPlan(
             scans: vec![],
             input_sources,
             stream: None,
-            runtime,
             metrics,
             metrics_update_interval,
             metrics_last_update_time: Instant::now(),
@@ -559,7 +570,7 @@ pub unsafe extern "system" fn Java_org_apache_comet_Native_executePlan(
         loop {
             // Polling the stream.
             let next_item = exec_context.stream.as_mut().unwrap().next();
-            let poll_output = exec_context.runtime.block_on(async { poll!(next_item) });
+            let poll_output = get_runtime().block_on(async { poll!(next_item) });
 
             // update metrics at interval
             if let Some(interval) = exec_context.metrics_update_interval {

diff --git a/native/core/src/parquet/mod.rs b/native/core/src/parquet/mod.rs
@@ -44,6 +44,7 @@ use jni::{
 };
 
 use self::util::jni::TypePromotionInfo;
+use crate::execution::jni_api::get_runtime;
 use crate::execution::operators::ExecutionError;
 use crate::execution::planner::PhysicalPlanner;
 use crate::execution::serde;
@@ -606,7 +607,6 @@ enum ParquetReaderState {
 }
 /// Parquet read context maintained across multiple JNI calls.
 struct BatchContext {
-    runtime: tokio::runtime::Runtime,
     batch_stream: Option<SendableRecordBatchStream>,
     current_batch: Option<RecordBatch>,
     reader_state: ParquetReaderState,
@@ -652,8 +652,6 @@ pub unsafe extern "system" fn Java_org_apache_comet_parquet_Native_initRecordBat
     data_schema: jbyteArray,
     session_timezone: jstring,
     batch_size: jint,
-    worker_threads: jint,
-    blocking_threads: jint,
 ) -> jlong {
     try_unwrap_or_throw(&e, |mut env| unsafe {
         let session_config = SessionConfig::new().with_batch_size(batch_size as usize);
@@ -666,12 +664,6 @@ pub unsafe extern "system" fn Java_org_apache_comet_parquet_Native_initRecordBat
             .unwrap()
             .into();
 
-        let runtime = tokio::runtime::Builder::new_multi_thread()
-            .worker_threads(worker_threads as usize)
-            .max_blocking_threads(blocking_threads as usize)
-            .enable_all()
-            .build()?;
-
         let (object_store_url, object_store_path) =
             prepare_object_store(session_ctx.runtime_env(), path.clone())?;
 
@@ -718,7 +710,6 @@ pub unsafe extern "system" fn Java_org_apache_comet_parquet_Native_initRecordBat
         let batch_stream = Some(scan.execute(partition_index, session_ctx.task_ctx())?);
 
         let ctx = BatchContext {
-            runtime,
             batch_stream,
             current_batch: None,
             reader_state: ParquetReaderState::Init,
@@ -738,7 +729,7 @@ pub extern "system" fn Java_org_apache_comet_parquet_Native_readNextRecordBatch(
         let context = get_batch_context(handle)?;
         let mut rows_read: i32 = 0;
         let batch_stream = context.batch_stream.as_mut().unwrap();
-        let runtime = &context.runtime;
+        let runtime = get_runtime();
 
         loop {
             let next_item = batch_stream.next();

diff --git a/spark/src/main/scala/org/apache/comet/CometExecIterator.scala b/spark/src/main/scala/org/apache/comet/CometExecIterator.scala
@@ -25,7 +25,7 @@ import org.apache.spark.network.util.ByteUnit
 import org.apache.spark.sql.comet.CometMetricNode
 import org.apache.spark.sql.vectorized._
 
-import org.apache.comet.CometConf.{COMET_BATCH_SIZE, COMET_BLOCKING_THREADS, COMET_DEBUG_ENABLED, COMET_EXEC_MEMORY_POOL_TYPE, COMET_EXPLAIN_NATIVE_ENABLED, COMET_METRICS_UPDATE_INTERVAL, COMET_WORKER_THREADS}
+import org.apache.comet.CometConf.{COMET_BATCH_SIZE, COMET_DEBUG_ENABLED, COMET_EXEC_MEMORY_POOL_TYPE, COMET_EXPLAIN_NATIVE_ENABLED, COMET_METRICS_UPDATE_INTERVAL}
 import org.apache.comet.vector.NativeUtil
 
 /**
@@ -92,9 +92,7 @@ class CometExecIterator(
       memoryLimitPerTask = getMemoryLimitPerTask(conf),
       taskAttemptId = TaskContext.get().taskAttemptId,
       debug = COMET_DEBUG_ENABLED.get(),
-      explain = COMET_EXPLAIN_NATIVE_ENABLED.get(),
-      workerThreads = COMET_WORKER_THREADS.get(),
-      blockingThreads = COMET_BLOCKING_THREADS.get())
+      explain = COMET_EXPLAIN_NATIVE_ENABLED.get())
   }
 
   private var nextBatch: Option[ColumnarBatch] = None

diff --git a/spark/src/main/scala/org/apache/comet/Native.scala b/spark/src/main/scala/org/apache/comet/Native.scala
@@ -66,9 +66,7 @@ class Native extends NativeBase {
       memoryLimitPerTask: Long,
       taskAttemptId: Long,
       debug: Boolean,
-      explain: Boolean,
-      workerThreads: Int,
-      blockingThreads: Int): Long
+      explain: Boolean): Long
   // scalastyle:on
 
   /**

diff --git a/spark/src/main/scala/org/apache/comet/parquet/CometParquetFileFormat.scala b/spark/src/main/scala/org/apache/comet/parquet/CometParquetFileFormat.scala
@@ -233,10 +233,6 @@ object CometParquetFileFormat extends Logging with ShimSQLConf {
       CometConf.COMET_EXCEPTION_ON_LEGACY_DATE_TIMESTAMP.key,
       CometConf.COMET_EXCEPTION_ON_LEGACY_DATE_TIMESTAMP.get())
     hadoopConf.setInt(CometConf.COMET_BATCH_SIZE.key, CometConf.COMET_BATCH_SIZE.get())
-    hadoopConf.setInt(CometConf.COMET_WORKER_THREADS.key, CometConf.COMET_WORKER_THREADS.get())
-    hadoopConf.setInt(
-      CometConf.COMET_BLOCKING_THREADS.key,
-      CometConf.COMET_BLOCKING_THREADS.get())
   }
 
   def getDatetimeRebaseSpec(