takes only one read transaction per thread

index-scheduler/src/batch.rs

@@ -142,22 +142,28 @@ pub(crate) enum IndexOperation {
 
 impl Batch {
     /// Return the task ids associated with this batch.
-    pub fn ids(&self) -> Vec<TaskId> {
+    pub fn ids(&self) -> RoaringBitmap {
         match self {
             Batch::TaskCancelation { task, .. }
             | Batch::Dump(task)
             | Batch::IndexCreation { task, .. }
-            | Batch::IndexUpdate { task, .. } => vec![task.uid],
+            | Batch::IndexUpdate { task, .. } => {
+                RoaringBitmap::from_sorted_iter(std::iter::once(task.uid)).unwrap()
+            }
             Batch::SnapshotCreation(tasks)
             | Batch::TaskDeletions(tasks)
-            | Batch::IndexDeletion { tasks, .. } => tasks.iter().map(|task| task.uid).collect(),
+            | Batch::IndexDeletion { tasks, .. } => {
+                RoaringBitmap::from_iter(tasks.iter().map(|task| task.uid))
+            }
             Batch::IndexOperation { op, .. } => match op {
                 IndexOperation::DocumentOperation { tasks, .. }
                 | IndexOperation::Settings { tasks, .. }
                 | IndexOperation::DocumentClear { tasks, .. } => {
-                    tasks.iter().map(|task| task.uid).collect()
+                    RoaringBitmap::from_iter(tasks.iter().map(|task| task.uid))
+                }
+                IndexOperation::IndexDocumentDeletionByFilter { task, .. } => {
+                    RoaringBitmap::from_sorted_iter(std::iter::once(task.uid)).unwrap()
                 }
-                IndexOperation::IndexDocumentDeletionByFilter { task, .. } => vec![task.uid],
                 IndexOperation::SettingsAndDocumentOperation {
                     document_import_tasks: tasks,
                     settings_tasks: other,
@@ -167,9 +173,11 @@ impl Batch {
                     cleared_tasks: tasks,
                     settings_tasks: other,
                     ..
-                } => tasks.iter().chain(other).map(|task| task.uid).collect(),
+                } => RoaringBitmap::from_iter(tasks.iter().chain(other).map(|task| task.uid)),
             },
-            Batch::IndexSwap { task } => vec![task.uid],
+            Batch::IndexSwap { task } => {
+                RoaringBitmap::from_sorted_iter(std::iter::once(task.uid)).unwrap()
+            }
         }
     }
 

index-scheduler/src/lib.rs

@@ -37,8 +37,8 @@ use std::fs::File;
 use std::io::{self, BufReader, Read};
 use std::ops::{Bound, RangeBounds};
 use std::path::{Path, PathBuf};
-use std::sync::atomic::AtomicBool;
-use std::sync::atomic::Ordering::Relaxed;
+use std::sync::atomic::Ordering::{self, Relaxed};
+use std::sync::atomic::{AtomicBool, AtomicU32};
 use std::sync::{Arc, RwLock};
 use std::time::Duration;
 
@@ -60,6 +60,7 @@ use meilisearch_types::milli::{self, CboRoaringBitmapCodec, Index, RoaringBitmap
 use meilisearch_types::task_view::TaskView;
 use meilisearch_types::tasks::{Kind, KindWithContent, Status, Task};
 use puffin::FrameView;
+use rayon::current_num_threads;
 use rayon::prelude::{IntoParallelIterator, ParallelIterator};
 use roaring::RoaringBitmap;
 use synchronoise::SignalEvent;
@@ -1139,15 +1140,13 @@ impl IndexScheduler {
         drop(rtxn);
 
         // 1. store the starting date with the bitmap of processing tasks.
-        let mut ids = batch.ids();
-        ids.sort_unstable();
+        let ids = batch.ids();
         let processed_tasks = ids.len();
-        let processing_tasks = RoaringBitmap::from_sorted_iter(ids.iter().copied()).unwrap();
         let started_at = OffsetDateTime::now_utc();
 
         // We reset the must_stop flag to be sure that we don't stop processing tasks
         self.must_stop_processing.reset();
-        self.processing_tasks.write().unwrap().start_processing_at(started_at, processing_tasks);
+        self.processing_tasks.write().unwrap().start_processing_at(started_at, ids.clone());
 
         #[cfg(test)]
         self.breakpoint(Breakpoint::BatchCreated);
@@ -1243,7 +1242,7 @@ impl IndexScheduler {
                 let error: ResponseError = err.into();
                 for id in ids.iter() {
                     let mut task = self
-                        .get_task(&wtxn, *id)
+                        .get_task(&wtxn, id)
                         .map_err(|e| Error::TaskDatabaseUpdate(Box::new(e)))?
                         .ok_or(Error::CorruptedTaskQueue)?;
                     task.started_at = Some(started_at);
@@ -1273,17 +1272,21 @@ impl IndexScheduler {
         // Once the tasks are commited, we should delete all the update files associated ASAP to avoid leaking files in case of a restart
         tracing::debug!("Deleting the upadate files");
 
-        ids.into_par_iter().try_for_each(|id| -> Result<()> {
+        //We take one read transaction **per thread**. Then, every thread is going to pull out new IDs from the roaring bitmap with the help of an atomic shared index into the bitmap
+        let idx = AtomicU32::new(0);
+        (0..current_num_threads()).into_par_iter().try_for_each(|_| -> Result<()> {
             let rtxn = self.read_txn()?;
-            let task = self
-                .get_task(&rtxn, id)
-                .map_err(|e| Error::TaskDatabaseUpdate(Box::new(e)))?
-                .ok_or(Error::CorruptedTaskQueue)?;
-            if let Err(e) = self.delete_persisted_task_data(&task) {
-                tracing::error!(
-                    "Failure to delete the content files associated with task {}. Error: {e}",
-                    task.uid
-                );
+            while let Some(id) = ids.select(idx.fetch_add(1, Ordering::Relaxed)) {
+                let task = self
+                    .get_task(&rtxn, id)
+                    .map_err(|e| Error::TaskDatabaseUpdate(Box::new(e)))?
+                    .ok_or(Error::CorruptedTaskQueue)?;
+                if let Err(e) = self.delete_persisted_task_data(&task) {
+                    tracing::error!(
+                        "Failure to delete the content files associated with task {}. Error: {e}",
+                        task.uid
+                    );
+                }
             }
             Ok(())
         })?;
@@ -1696,7 +1699,7 @@ pub enum TickOutcome {
     /// The scheduler should immediately attempt another `tick`.
     ///
     /// The `usize` field contains the number of processed tasks.
-    TickAgain(usize),
+    TickAgain(u64),
     /// The scheduler should wait for an external signal before attempting another `tick`.
     WaitForSignal,
 }