Add ParquetObjectReader::with_runtime (apache#6248)

parquet/src/arrow/async_reader/store.rs

@@ -22,11 +22,12 @@ use bytes::Bytes;
 use futures::future::BoxFuture;
 use futures::{FutureExt, TryFutureExt};
 
-use object_store::{ObjectMeta, ObjectStore};
-
 use crate::arrow::async_reader::{AsyncFileReader, MetadataLoader};
-use crate::errors::Result;
+use crate::errors::{ParquetError, Result};
 use crate::file::metadata::ParquetMetaData;
+use object_store::path::Path;
+use object_store::{ObjectMeta, ObjectStore};
+use tokio::runtime::Handle;
 
 /// Reads Parquet files in object storage using [`ObjectStore`].
 ///
@@ -59,6 +60,7 @@ pub struct ParquetObjectReader {
     metadata_size_hint: Option<usize>,
     preload_column_index: bool,
     preload_offset_index: bool,
+    runtime: Option<Handle>,
 }
 
 impl ParquetObjectReader {
@@ -72,6 +74,7 @@ impl ParquetObjectReader {
             metadata_size_hint: None,
             preload_column_index: false,
             preload_offset_index: false,
+            runtime: None,
         }
     }
 
@@ -99,27 +102,57 @@ impl ParquetObjectReader {
             ..self
         }
     }
+
+    /// Perform IO on the provided tokio runtime
+    ///
+    /// Tokio is a cooperative scheduler, and relies on tasks yielding in a timely manner
+    /// to service IO. Therefore, running IO and CPU-bound tasks, such as parquet decoding,
+    /// on the same tokio runtime can lead to degraded throughput, dropped connections and
+    /// other issues. For more information see [here].
+    ///
+    /// [here]: https://www.influxdata.com/blog/using-rustlangs-async-tokio-runtime-for-cpu-bound-tasks/
+    pub fn with_runtime(self, handle: Handle) -> Self {
+        Self {
+            runtime: Some(handle),
+            ..self
+        }
+    }
+
+    fn spawn<F, O>(&self, f: F) -> BoxFuture<'_, Result<O>>
+    where
+        F: for<'a> FnOnce(&'a Arc<dyn ObjectStore>, &'a Path) -> BoxFuture<'a, Result<O>>
+            + Send
+            + 'static,
+        O: Send + 'static,
+    {
+        match &self.runtime {
+            Some(handle) => {
+                let path = self.meta.location.clone();
+                let store = Arc::clone(&self.store);
+                let fut = handle.spawn(async move { f(&store, &path).await });
+                fut.unwrap_or_else(|e| match e.try_into_panic() {
+                    Ok(p) => std::panic::resume_unwind(p),
+                    Err(e) => Err(ParquetError::External(Box::new(e))),
+                })
+                .boxed()
+            }
+            None => f(&self.store, &self.meta.location),
+        }
+    }
 }
 
 impl AsyncFileReader for ParquetObjectReader {
     fn get_bytes(&mut self, range: Range<usize>) -> BoxFuture<'_, Result<Bytes>> {
-        self.store
-            .get_range(&self.meta.location, range)
-            .map_err(|e| e.into())
-            .boxed()
+        self.spawn(|store, path| store.get_range(path, range).map_err(|e| e.into()).boxed())
     }
 
     fn get_byte_ranges(&mut self, ranges: Vec<Range<usize>>) -> BoxFuture<'_, Result<Vec<Bytes>>>
     where
         Self: Send,
     {
-        async move {
-            self.store
-                .get_ranges(&self.meta.location, &ranges)
-                .await
-                .map_err(|e| e.into())
-        }
-        .boxed()
+        self.spawn(move |store, path| {
+            async move { store.get_ranges(path, &ranges).await.map_err(|e| e.into()) }.boxed()
+        })
     }
 
     fn get_metadata(&mut self) -> BoxFuture<'_, Result<Arc<ParquetMetaData>>> {