[GitHub] [arrow-datafusion] alamb commented on a diff in pull request #5197: fix(MemTable): make it cancel-safe and fix parallelism

["alamb (via GitHub)" <gi...@apache.org>]

alamb commented on code in PR #5197:
URL: https://github.com/apache/arrow-datafusion/pull/5197#discussion_r1097757843


##########
datafusion/core/src/datasource/memory.rs:
##########
@@ -76,20 +77,26 @@ impl MemTable {
             .map(|part_i| {
                 let task = state.task_ctx();
                 let exec = exec.clone();
-                tokio::spawn(async move {
+                let task = tokio::spawn(async move {
                     let stream = exec.execute(part_i, task)?;
                     common::collect(stream).await
-                })
+                });
+
+                AbortOnDropSingle::new(task)
             })
             // this collect *is needed* so that the join below can
             // switch between tasks
             .collect::<Vec<_>>();
 
         let mut data: Vec<Vec<RecordBatch>> =
             Vec::with_capacity(exec.output_partitioning().partition_count());
-        for task in tasks {
-            let result = task.await.expect("MemTable::load could not join task")?;
-            data.push(result);
+
+        for result in futures::future::join_all(tasks).await {
+            data.push(result.map_err(|_| {
+                DataFusionError::Internal(
+                    "MemTable::load could not join task".to_string(),
+                )

Review Comment:
   I think it would help if we could preserve the original error here rather than turning it into an internal error
   
   Perhaps using `DataFusionError::Context`
   ```suggestion
               data.push(result.map_err(|e| {
                   DataFusionError::Context(
                       "MemTable::load could not join task".to_string(), Box::new(e)
                   )
   ```
   
   
   



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