Github user andrewor14 commented on a diff in the pull request:
https://github.com/apache/spark/pull/11613#discussion_r55899254
--- Diff:
core/src/main/scala/org/apache/spark/storage/memory/MemoryStore.scala ---
@@ -100,48 +92,136 @@ private[spark] class MemoryStore(
*/
def putBytes(blockId: BlockId, size: Long, _bytes: () => ByteBuffer):
Boolean = {
require(!contains(blockId), s"Block $blockId is already present in the
MemoryStore")
- // Work on a duplicate - since the original input might be used
elsewhere.
- lazy val bytes = _bytes().duplicate().rewind().asInstanceOf[ByteBuffer]
- val putSuccess = tryToPut(blockId, () => bytes, size, deserialized =
false)
- if (putSuccess) {
+ if (memoryManager.acquireStorageMemory(blockId, size)) {
+ // We acquired enough memory for the block, so go ahead and put it
+ // Work on a duplicate - since the original input might be used
elsewhere.
+ val bytes = _bytes().duplicate().rewind().asInstanceOf[ByteBuffer]
assert(bytes.limit == size)
+ val entry = new MemoryEntry(bytes, size, deserialized = false)
+ entries.synchronized {
+ entries.put(blockId, entry)
+ }
+ logInfo("Block %s stored as bytes in memory (estimated size %s, free
%s)".format(
+ blockId, Utils.bytesToString(size),
Utils.bytesToString(blocksMemoryUsed)))
+ true
+ } else {
+ false
}
- putSuccess
}
/**
* Attempt to put the given block in memory store.
*
- * @return the estimated size of the stored data if the put() succeeded,
or an iterator
- * in case the put() failed (the returned iterator lets callers
fall back to the disk
- * store if desired).
+ * @return in case of success, the estimated the estimated size of the
stored data. In case of
+ * failure, return an iterator contianing the values of the
block. The returned iterator
+ * will be backed by the combination of the partially-unrolled
block and the remaining
+ * elements of the original input iterator. The caller must
either fully consume this
+ * iterator or call `close()` on it in order to free the storage
memory consumed by the
+ * partially-unrolled block.
*/
private[storage] def putIterator(
blockId: BlockId,
values: Iterator[Any],
- level: StorageLevel): Either[Iterator[Any], Long] = {
+ level: StorageLevel): Either[PartiallyUnrolledIterator, Long] = {
+
require(!contains(blockId), s"Block $blockId is already present in the
MemoryStore")
- val unrolledValues = unrollSafely(blockId, values)
- unrolledValues match {
- case Left(arrayValues) =>
- // Values are fully unrolled in memory, so store them as an array
- if (level.deserialized) {
- val sizeEstimate =
SizeEstimator.estimate(arrayValues.asInstanceOf[AnyRef])
- if (tryToPut(blockId, () => arrayValues, sizeEstimate,
deserialized = true)) {
- Right(sizeEstimate)
- } else {
- Left(arrayValues.toIterator)
+
+ // It's possible that the iterator is too large to materialize and
store in memory. To avoid
+ // OOM exceptions, this method will gradually unroll the iterator
while periodically checking
+ // whether there is enough free memory.
+
+ // Number of elements unrolled so far
+ var elementsUnrolled = 0
+ // Whether there is still enough memory for us to continue unrolling
this block
+ var keepUnrolling = true
+ // Initial per-task memory to request for unrolling blocks (bytes).
+ val initialMemoryThreshold = unrollMemoryThreshold
+ // How often to check whether we need to request more memory
+ val memoryCheckPeriod = 16
+ // Memory currently reserved by this task for this particular
unrolling operation
+ var memoryThreshold = initialMemoryThreshold
+ // Memory to request as a multiple of current vector size
+ val memoryGrowthFactor = 1.5
+ // Keep track of unroll memory used by this particular block /
putIterator() operation
+ var unrollMemoryUsedByThisBlock = 0L
+ // Underlying vector for unrolling the block
+ var vector = new SizeTrackingVector[Any]
+
+ // Request enough memory to begin unrolling
+ keepUnrolling = reserveUnrollMemoryForThisTask(blockId,
initialMemoryThreshold)
+
+ if (!keepUnrolling) {
+ logWarning(s"Failed to reserve initial memory threshold of " +
+ s"${Utils.bytesToString(initialMemoryThreshold)} for computing
block $blockId in memory.")
+ } else {
+ unrollMemoryUsedByThisBlock += initialMemoryThreshold
+ }
+
+ // Unroll this block safely, checking whether we have exceeded our
threshold periodically
+ while (values.hasNext && keepUnrolling) {
+ vector += values.next()
+ if (elementsUnrolled % memoryCheckPeriod == 0) {
+ // If our vector's size has exceeded the threshold, request more
memory
+ val currentSize = vector.estimateSize()
+ if (currentSize >= memoryThreshold) {
+ val amountToRequest = (currentSize * memoryGrowthFactor -
memoryThreshold).toLong
+ keepUnrolling = reserveUnrollMemoryForThisTask(blockId,
amountToRequest)
+ if (keepUnrolling) {
+ unrollMemoryUsedByThisBlock += amountToRequest
}
+ // New threshold is currentSize * memoryGrowthFactor
+ memoryThreshold += amountToRequest
+ }
+ }
+ elementsUnrolled += 1
+ }
+
+ if (keepUnrolling) {
+ // We successfully unrolled the entirety of this block
+ val arrayValues = vector.toArray
+ vector = null
+ val entry = if (level.deserialized) {
+ val sizeEstimate =
SizeEstimator.estimate(arrayValues.asInstanceOf[AnyRef])
+ new MemoryEntry(arrayValues, sizeEstimate, deserialized = true)
+ } else {
+ val bytes = blockManager.dataSerialize(blockId,
arrayValues.iterator)
+ new MemoryEntry(bytes, bytes.limit, deserialized = false)
+ }
+ val size = entry.size
+ val acquiredStorageMemory = {
+ if (unrollMemoryUsedByThisBlock == size) {
+ true
+ } else if (unrollMemoryUsedByThisBlock < size) {
+ memoryManager.acquireStorageMemory(blockId, size -
unrollMemoryUsedByThisBlock)
} else {
- val bytes = blockManager.dataSerialize(blockId,
arrayValues.iterator)
- if (tryToPut(blockId, () => bytes, bytes.limit, deserialized =
false)) {
- Right(bytes.limit())
- } else {
- Left(arrayValues.toIterator)
- }
+ memoryManager.releaseUnrollMemory(unrollMemoryUsedByThisBlock -
size)
+ true
}
- case Right(iteratorValues) =>
- Left(iteratorValues)
+ }
+ if (acquiredStorageMemory) {
+ // We acquired enough memory for the block, so go ahead and put it
+ memoryManager.synchronized {
+ unrollMemoryMap(currentTaskAttemptId()) -=
unrollMemoryUsedByThisBlock
--- End diff --
actually, why do we release anything here? Before entering this if case
we're guaranteed to hold `unroll memory == block size`. We still need to keep
this storage memory because we now store the array in `entries`.
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