Github user viirya commented on a diff in the pull request:
https://github.com/apache/spark/pull/16603#discussion_r96589311
--- Diff: core/src/main/java/org/apache/spark/memory/TaskMemoryManager.java
---
@@ -144,8 +164,24 @@ public long acquireExecutionMemory(long required,
MemoryConsumer consumer) {
// spilling, avoid to have too many spilled files.
if (got < required) {
// Call spill() on other consumers to release memory
+ // Sort the consumers according their memory usage. So we avoid
spilling the same consumer
+ // which is just spilled in last few times and re-spilling on it
will produce many small
+ // spill files.
+ List<MemoryConsumer> sortedList = new
ArrayList<>(consumers.size());
for (MemoryConsumer c: consumers) {
if (c != consumer && c.getUsed() > 0 && c.getMode() == mode) {
+ sortedList.add(c);
+ }
+ }
+ Collections.sort(sortedList, new ConsumerComparator());
+ for (int listIndex = 0; listIndex < sortedList.size();
listIndex++) {
+ MemoryConsumer c = sortedList.get(listIndex);
+ // Try to only spill on the consumer which has the required size
of memory.
+ // As the consumers are sorted in descending order, if the next
consumer doesn't have
+ // the required memory, then we need to spill the current
consumer at least.
+ boolean doSpill = (listIndex + 1) == sortedList.size() ||
+ sortedList.get(listIndex + 1).getUsed() < (required - got);
+ if (doSpill) {
--- End diff --
I am not sure how we keep iterating the consumers in existing impl. As we
loop on all consumers, no matter we spill it or not or how many memory we
released, we won't go back to it and previous consumers, right?
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