hail-is · ehigham · Feb 10, 2026
diff --git a/hail/hail/src/is/hail/annotations/RegionPool.scala b/hail/hail/src/is/hail/annotations/RegionPool.scala
@@ -118,9 +118,7 @@ final class RegionPool private (strictMemoryCheck: Boolean, threadName: String,
     }
   }
 
-  def getRegion(): Region = getRegion(Region.REGULAR)
-
-  def getRegion(size: Int): Region = {
+  def getRegion(size: Int = Region.REGULAR): Region = {
     val r = new Region(size, this)
     r.memory = getMemory(size)
     r
@@ -154,11 +152,29 @@ final class RegionPool private (strictMemoryCheck: Boolean, threadName: String,
 
   def report(context: String): Unit = {
     val inBlocks = bytesInBlocks()
+    val (chunksAllocated, cacheHits) = chunkCache.getUsage()
 
     logger.info(
-      s"RegionPool: $context: ${readableBytes(totalAllocatedBytes)} allocated (${readableBytes(inBlocks)} blocks / " +
-        s"${readableBytes(totalAllocatedBytes - inBlocks)} chunks), regions.size = ${regions.size}, " +
-        s"$numJavaObjects current java objects, thread $threadID: $threadName"
+      s"""RegionPool: $context
+         |  thread:
+         |    id:   $threadID
+         |    name: $threadName
+         |  objects:  $numJavaObjects
+         |  allocations:
+         |    peak:     $getHighestTotalUsage
+         |    total:    ${readableBytes(totalAllocatedBytes)}
+         |    blocks:   ${readableBytes(inBlocks)}
+         |    chunks:   ${readableBytes(totalAllocatedBytes - inBlocks)}
+         |  regions:
+         |    total:  ${regions.size}
+         |    free:   ${freeRegions.size}
+         |  blocks:
+         |    total:  ${blocks.sum}
+         |    free:   ${freeBlocks.view.map(_.size).sum}
+         |  chunks:
+         |    total:  $chunksAllocated
+         |    reused: $cacheHits
+         | """.stripMargin
     )
 //    logger.info("-----------STACK_TRACES---------")
 //    val stacks: String = regions.result().toIndexedSeq.flatMap(r => r.stackTrace.map((r.getTotalChunkMemory(), _))).foldLeft("")((a: String, b) => a + "\n" + b.toString())
@@ -170,8 +186,6 @@ final class RegionPool private (strictMemoryCheck: Boolean, threadName: String,
   def scopedSmallRegion[T](f: Region => T): T = using(Region(Region.SMALL, pool = this))(f)
   def scopedTinyRegion[T](f: Region => T): T = using(Region(Region.TINY, pool = this))(f)
 
-  override def finalize(): Unit = close()
-
   private[this] var closed: Boolean = false
 
   override def close(): Unit = {

diff --git a/hail/hail/src/is/hail/backend/ExecuteContext.scala b/hail/hail/src/is/hail/backend/ExecuteContext.scala
@@ -3,7 +3,6 @@ package is.hail.backend
 import is.hail.HailFeatureFlags
 import is.hail.annotations.{Region, RegionPool}
 import is.hail.asm4s.HailClassLoader
-import is.hail.backend.local.LocalTaskContext
 import is.hail.expr.ir.{BaseIR, CompileCache, Compiled}
 import is.hail.expr.ir.LoweredTableReader.LoweredTableReaderCoercer
 import is.hail.expr.ir.lowering.IrMetadata
@@ -72,7 +71,7 @@ object ExecuteContext {
     coercerCache: mutable.Map[Any, LoweredTableReaderCoercer],
   )(
     f: ExecuteContext => T
-  ): T = {
+  ): T =
     RegionPool.scoped { pool =>
       pool.scopedRegion { region =>
         using(new ExecuteContext(
@@ -94,7 +93,6 @@ object ExecuteContext {
         ))(f(_))
       }
     }
-  }
 
   def createTmpPathNoCleanup(tmpdir: String, prefix: String, extension: String = null): String = {
     val random = new SecureRandom()
@@ -113,7 +111,7 @@ class ExecuteContext(
   val backend: Backend,
   val references: Map[String, ReferenceGenome],
   val fs: FS,
-  val r: Region,
+  override val r: Region,
   val timer: ExecutionTimer,
   val tempFileManager: TempFileManager,
   val theHailClassLoader: HailClassLoader,
@@ -123,7 +121,7 @@ class ExecuteContext(
   val CompileCache: CompileCache,
   val PersistedIrCache: mutable.Map[Int, BaseIR],
   val PersistedCoercerCache: mutable.Map[Any, LoweredTableReaderCoercer],
-) extends Closeable {
+) extends HailTaskContext with Closeable {
 
   val rngNonce: Long =
     try
@@ -142,10 +140,14 @@ class ExecuteContext(
 
   val memo: mutable.Map[Any, Any] = new mutable.HashMap[Any, Any]()
 
-  val taskContext: HailTaskContext = new LocalTaskContext(0, 0)
+  private[this] val onCloseTasks = mutable.ArrayBuffer.empty[() => Unit]
+  override def onClose(f: () => Unit): Unit = onCloseTasks += f
+
+  def run[A](f: Compiled[A])(implicit E: Enclosing): A =
+    time(f(theHailClassLoader, fs, this, r))
 
   def scopedExecution[T](f: Compiled[T])(implicit E: Enclosing): T =
-    using(new LocalTaskContext(0, 0))(tc => time(f(theHailClassLoader, fs, tc, r)))
+    r.pool.scopedRegion(r => local(r = r)(_.run(f)))
 
   def createTmpPath(prefix: String, extension: String = null, local: Boolean = false): String =
     tempFileManager.newTmpPath(if (local) localTmpdir else tmpdir, prefix, extension)
@@ -159,8 +161,8 @@ class ExecuteContext(
   def shouldLogIR(): Boolean = !shouldNotLogIR()
 
   override def close(): Unit = {
+    onCloseTasks.foreach(_())
     tempFileManager.close()
-    taskContext.close()
   }
 
   def time[A](block: => A)(implicit E: Enclosing): A =
@@ -179,7 +181,7 @@ class ExecuteContext(
     flags: HailFeatureFlags = this.flags,
     irMetadata: IrMetadata = this.irMetadata,
     blockMatrixCache: mutable.Map[String, BlockMatrix] = this.BlockMatrixCache,
-    codeCache: CompileCache = this.CompileCache,
+    compileCache: CompileCache = this.CompileCache,
     persistedIrCache: mutable.Map[Int, BaseIR] = this.PersistedIrCache,
     persistedCoercerCache: mutable.Map[Any, LoweredTableReaderCoercer] = this.PersistedCoercerCache,
   )(
@@ -198,7 +200,7 @@ class ExecuteContext(
       flags,
       irMetadata,
       blockMatrixCache,
-      codeCache,
+      compileCache,
       persistedIrCache,
       persistedCoercerCache,
     ))(f)

diff --git a/hail/hail/src/is/hail/backend/HailTaskContext.scala b/hail/hail/src/is/hail/backend/HailTaskContext.scala
@@ -1,50 +1,35 @@
 package is.hail.backend
 
-import is.hail.annotations.RegionPool
-import is.hail.utils._
+import is.hail.annotations.{Region, RegionPool}
+import is.hail.utils.using
 
 import scala.collection.mutable
 
-import java.io.Closeable
+trait HailTaskContext {
 
-class TaskFinalizer {
-  val closeables = mutable.ArrayBuffer.empty[Closeable]
+  /** region whose lifetime is at least as long as this task */
+  def r: Region
 
-  def clear(): Unit =
-    closeables.clear()
-
-  def addCloseable(c: Closeable): Unit =
-    closeables += c
-
-  def closeAll(): Unit = closeables.foreach(_.close())
+  /** register an action that will be called when this task completes */
+  def onClose(f: () => Unit): Unit
 }
 
-abstract class HailTaskContext extends AutoCloseable with Logging {
-  def stageId(): Int
-
-  def partitionId(): Int
-
-  def attemptNumber(): Int
-
-  private lazy val thePool = RegionPool()
-
-  def getRegionPool(): RegionPool = thePool
+object HailTaskContext {
+  def runPartition[A](partId: Int)(f: HailTaskContext => A): A =
+    using(new PartitionContext(partId))(f)
+}
 
-  val finalizers = mutable.ArrayBuffer.empty[TaskFinalizer]
+class PartitionContext(partId: Int) extends HailTaskContext with AutoCloseable {
+  private[this] val onCloseTasks = mutable.ArrayBuffer.empty[() => Unit]
 
-  def newFinalizer(): TaskFinalizer = {
-    val f = new TaskFinalizer
-    finalizers += f
-    f
-  }
+  private[this] val pool = RegionPool()
+  override val r: Region = Region(pool = pool)
+  override def onClose(f: () => Unit): Unit = onCloseTasks += f
 
   override def close(): Unit = {
-    logger.info(
-      s"TaskReport: stage=${stageId()}, partition=${partitionId()}, attempt=${attemptNumber()}, " +
-        s"peakBytes=${thePool.getHighestTotalUsage}, peakBytesReadable=${formatSpace(thePool.getHighestTotalUsage)}, " +
-        s"chunks requested=${thePool.getUsage._1}, cache hits=${thePool.getUsage._2}"
-    )
-    finalizers.foreach(_.closeAll())
-    thePool.close()
+    onCloseTasks.foreach(_())
+    r.close()
+    pool.logStats(s"Partition $partId")
+    pool.close()
   }
 }
diff --git a/hail/hail/src/is/hail/backend/local/LocalBackend.scala b/hail/hail/src/is/hail/backend/local/LocalBackend.scala
@@ -20,10 +20,6 @@ import com.fasterxml.jackson.core.StreamReadConstraints
 
 class LocalBroadcastValue[T](val value: T) extends BroadcastValue[T] with Serializable
 
-class LocalTaskContext(val partitionId: Int, val stageId: Int) extends HailTaskContext {
-  override def attemptNumber(): Int = 0
-}
-
 object LocalBackend extends Backend with Logging {
 
   // From https://github.com/hail-is/hail/issues/14580 :
@@ -43,16 +39,7 @@ object LocalBackend extends Backend with Logging {
   override def broadcast[T: ClassTag](value: T): BroadcastValue[T] =
     new LocalBroadcastValue[T](value)
 
-  private[this] var stageIdx: Int = 0
-
-  private[this] def nextStageId(): Int =
-    synchronized {
-      val current = stageIdx
-      stageIdx += 1
-      current
-    }
-
-  override def runtimeContext(ctx: ExecuteContext): DriverRuntimeContext = {
+  override def runtimeContext(ctx: ExecuteContext): DriverRuntimeContext =
     new DriverRuntimeContext {
 
       override val executionCache: ExecutionCache =
@@ -77,14 +64,10 @@ object LocalBackend extends Backend with Logging {
         var failure: Option[Throwable] =
           None
 
-        val stageId = nextStageId()
-
         try
           for (idx <- todo)
-            results += using(new LocalTaskContext(idx, stageId)) { htc =>
-              htc.getRegionPool().scopedRegion { r =>
-                f(ctx.theHailClassLoader, ctx.fs, htc, r)(globals, contexts(idx)) -> idx
-              }
+            results += ctx.scopedExecution { (hcl, fs, ctx, r) =>
+              (f(hcl, fs, ctx, r)(globals, contexts(idx)), idx)
             }
         catch {
           case NonFatal(t) =>
@@ -94,12 +77,10 @@ object LocalBackend extends Backend with Logging {
         (failure, results.result())
       }
     }
-  }
 
   override def defaultParallelism: Int = 1
 
-  override def close(): Unit =
-    synchronized { stageIdx = 0 }
+  override def close(): Unit = {}
 
   private[this] def _jvmLowerAndExecute(
     ctx: ExecuteContext,

diff --git a/hail/hail/src/is/hail/backend/service/ServiceBackend.scala b/hail/hail/src/is/hail/backend/service/ServiceBackend.scala
@@ -4,7 +4,6 @@ import is.hail.Revision
 import is.hail.backend._
 import is.hail.backend.Backend.PartitionFn
 import is.hail.backend.ExecutionCache.Flags.UseFastRestarts
-import is.hail.backend.local.LocalTaskContext
 import is.hail.backend.service.ServiceBackend.Flags._
 import is.hail.collection.FastSeq
 import is.hail.collection.compat.immutable.ArraySeq
@@ -361,10 +360,8 @@ class ServiceBackend(
         partitions.getOrElse(contexts.indices) match {
           case Seq(k) =>
             try
-              using(new LocalTaskContext(k, stageCount)) { htc =>
-                None -> htc.getRegionPool().scopedRegion { r =>
-                  FastSeq(f(ctx.theHailClassLoader, ctx.fs, htc, r)(globals, contexts(k)) -> k)
-                }
+              ctx.scopedExecution { (hcl, fs, htc, r) =>
+                (None, FastSeq(f(hcl, fs, htc, r)(globals, contexts(k)) -> k))
               }
             catch {
               case NonFatal(t) => Some(t) -> ArraySeq.empty

diff --git a/hail/hail/src/is/hail/backend/service/Worker.scala b/hail/hail/src/is/hail/backend/service/Worker.scala
@@ -19,12 +19,6 @@ import java.util
 import java.util.concurrent.Executors
 import java.util.concurrent.atomic.AtomicInteger
 
-class ServiceTaskContext(val partitionId: Int) extends HailTaskContext {
-  override def stageId(): Int = 0
-
-  override def attemptNumber(): Int = 0
-}
-
 class WorkerTimer extends Logging {
 
   var startTimes: mutable.Map[String, Long] = mutable.Map()
@@ -250,12 +244,11 @@ object Worker extends Logging {
       inputs.flatMap { case (globals, context, f) =>
         timer.enter("execute") {
           try
-            using(new ServiceTaskContext(partition)) { htc =>
-              retryTransientErrors {
-                htc.getRegionPool().scopedRegion { r =>
-                  Right(f(hcl, fs, htc, r)(globals, context))
-                }
-              }
+            HailTaskContext.runPartition(partition) { htc =>
+              retryTransientErrors(
+                Right(f(hcl, fs, htc, htc.r)(globals, context)),
+                Some(() => htc.r.clear()),
+              )
             }
           catch {
             case t: Throwable => Left(t)

diff --git a/hail/hail/src/is/hail/backend/spark/SparkBackend.scala b/hail/hail/src/is/hail/backend/spark/SparkBackend.scala
@@ -35,31 +35,23 @@ class SparkBroadcastValue[T](bc: Broadcast[T]) extends BroadcastValue[T] with Se
 }
 
 object SparkTaskContext {
-  def get(): SparkTaskContext = taskContext.get
+  def get: HailTaskContext = taskContext.get
 
-  private[this] val taskContext: ThreadLocal[SparkTaskContext] =
-    new ThreadLocal[SparkTaskContext]() {
-      override def initialValue(): SparkTaskContext = {
+  private[this] val taskContext: ThreadLocal[HailTaskContext] =
+    new ThreadLocal[HailTaskContext]() {
+      override def initialValue(): HailTaskContext = {
         val sparkTC = TaskContext.get()
         assert(sparkTC != null, "Spark Task Context was null, maybe this ran on the driver?")
-        sparkTC.addTaskCompletionListener[Unit]((_: TaskContext) => SparkTaskContext.finish()): Unit
 
-        // this must be the only place where SparkTaskContext classes are created
-        new SparkTaskContext(sparkTC)
+        val htc = new PartitionContext(sparkTC.stageId())
+        sparkTC.addTaskCompletionListener[Unit] { _ => htc.close(); remove(); }: Unit
+
+        htc
       }
     }
 
-  def finish(): Unit = {
-    taskContext.get().close()
+  def finish(): Unit =
     taskContext.remove()
-  }
-}
-
-class SparkTaskContext private[spark] (ctx: TaskContext) extends HailTaskContext {
-  self =>
-  override def stageId(): Int = ctx.stageId()
-  override def partitionId(): Int = ctx.partitionId()
-  override def attemptNumber(): Int = ctx.attemptNumber()
 }
 
 object SparkBackend extends Logging {
@@ -267,11 +259,9 @@ class SparkBackend(val spark: SparkSession) extends Backend with Logging {
 
             override def compute(partition: Partition, context: TaskContext)
               : Iterator[Array[Byte]] = {
-              val htc = SparkTaskContext.get()
-              htc.getRegionPool().scopedRegion { r =>
-                val g = f(unsafeHailClassLoaderForSparkWorkers, new HadoopFS(fsConfig), htc, r)
-                Iterator.single(g(globals, partition.asInstanceOf[RDDPartition].data))
-              }
+              val ctx = SparkTaskContext.get
+              val g = f(unsafeHailClassLoaderForSparkWorkers, new HadoopFS(fsConfig), ctx, ctx.r)
+              Iterator.single(g(globals, partition.asInstanceOf[RDDPartition].data))
             }
           }