devinjdangelo commented on code in PR #7452:
URL: https://github.com/apache/arrow-datafusion/pull/7452#discussion_r1317410490


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datafusion/core/src/datasource/file_format/write.rs:
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@@ -315,13 +299,90 @@ pub(crate) async fn create_writer(
     }
 }
 
+/// Serializes a single data stream in parallel and writes to an ObjectStore
+/// concurrently. Data order is preserved. In the event of an error,
+/// the ObjectStore writer is returned to the caller in addition to an error,
+/// so that the caller may handle aborting failed writes.
+async fn serialize_rb_stream_to_object_store(
+    mut data_stream: Pin<Box<dyn RecordBatchStream + Send>>,
+    mut serializer: Box<dyn BatchSerializer>,
+    mut writer: AbortableWrite<Box<dyn AsyncWrite + Send + Unpin>>,
+) -> std::result::Result<
+    (
+        Box<dyn BatchSerializer>,
+        AbortableWrite<Box<dyn AsyncWrite + Send + Unpin>>,
+        u64,
+    ),
+    (
+        AbortableWrite<Box<dyn AsyncWrite + Send + Unpin>>,
+        DataFusionError,
+    ),
+> {
+    let mut row_count = 0;
+    // Not using JoinSet here since we want to ulimately write to ObjectStore 
preserving file order
+    let mut serialize_tasks: Vec<JoinHandle<Result<(usize, Bytes), 
DataFusionError>>> =
+        Vec::new();
+    while let Some(maybe_batch) = data_stream.next().await {
+        let mut serializer_clone = match serializer.duplicate() {
+            Ok(s) => s,
+            Err(_) => {
+                return Err((
+                    writer,
+                    DataFusionError::Internal(
+                        "Unknown error writing to object store".into(),
+                    ),
+                ))
+            }
+        };
+        serialize_tasks.push(task::spawn(async move {
+            let batch = maybe_batch?;
+            let num_rows = batch.num_rows();
+            let bytes = serializer_clone.serialize(batch).await?;
+            Ok((num_rows, bytes))
+        }));
+    }
+    for serialize_result in serialize_tasks {
+        let result = serialize_result.await;
+        match result {
+            Ok(res) => {
+                let (cnt, bytes) = match res {
+                    Ok(r) => r,
+                    Err(e) => return Err((writer, e)),
+                };
+                row_count += cnt;
+                match writer.write_all(&bytes).await {
+                    Ok(_) => (),
+                    Err(_) => {
+                        return Err((
+                            writer,
+                            DataFusionError::Internal(
+                                "Unknown error writing to object store".into(),
+                            ),
+                        ))
+                    }
+                };
+            }
+            Err(_) => {
+                return Err((
+                    writer,
+                    DataFusionError::Internal(
+                        "Unknown error writing to object store".into(),
+                    ),
+                ))
+            }
+        }
+    }
+
+    Ok((serializer, writer, row_count as u64))
+}

Review Comment:
   Thanks for the issue links. I tried calling yield_now().await every N 
iterations, but the FIFO insert test only passes when N==1 (i.e. 
yield_now().await on every iteration). 
   
   I just pushed up a possible option of calling yield_now() if the input is 
unbounded, otherwise skipping it. That allows bounded tables to benefit fully 
from the parallelization but still allowing fifo tests to pass as they 
currently do. 
   
   The fifo test is not a multithreaded runtime, but when I benchmark 
performance I am running in a multithreaded runtime, yes.



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