xintongsong commented on a change in pull request #9693: [FLINK-13984] Separate
on-heap and off-heap managed memory pools
URL: https://github.com/apache/flink/pull/9693#discussion_r327957575
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/memory/MemoryManager.java
##########
@@ -394,74 +318,79 @@ public void release(Collection<MemorySegment> segments) {
return;
}
- // -------------------- BEGIN CRITICAL SECTION
-------------------
- synchronized (lock) {
- if (isShutDown) {
- throw new IllegalStateException("Memory manager
has been shut down.");
- }
+ Preconditions.checkState(!isShutDown, "Memory manager has been
shut down.");
- // since concurrent modifications to the collection
- // can disturb the release, we need to try potentially
multiple times
- boolean successfullyReleased = false;
- do {
- final Iterator<MemorySegment> segmentsIterator
= segments.iterator();
+ EnumMap<MemoryType, Long> releasedMemory = new
EnumMap<>(MemoryType.class);
- Object lastOwner = null;
- Set<MemorySegment> segsForOwner = null;
+ // since concurrent modifications to the collection
+ // can disturb the release, we need to try potentially multiple
times
+ boolean successfullyReleased = false;
+ do {
+ Iterator<MemorySegment> segmentsIterator =
segments.iterator();
- try {
- // go over all segments
- while (segmentsIterator.hasNext()) {
-
- final MemorySegment seg =
segmentsIterator.next();
- if (seg == null ||
seg.isFreed()) {
- continue;
- }
-
- final Object owner =
seg.getOwner();
-
- try {
- // get the list of
segments by this owner only if it is a different owner than for
- // the previous one (or
it is the first segment)
- if (lastOwner != owner)
{
- lastOwner =
owner;
- segsForOwner =
this.allocatedSegments.get(owner);
- }
-
- // remove the segment
from the list
- if (segsForOwner !=
null) {
-
segsForOwner.remove(seg);
- if
(segsForOwner.isEmpty()) {
-
this.allocatedSegments.remove(owner);
- }
- }
-
- if (isPreAllocated) {
-
memoryPool.returnSegmentToPool(seg);
- }
- else {
- seg.free();
-
numNonAllocatedPages++;
- }
- }
- catch (Throwable t) {
- throw new
RuntimeException(
- "Error
removing book-keeping reference to allocated memory segment.", t);
- }
+ //noinspection ProhibitedExceptionCaught
+ try {
+ MemorySegment segment = null;
+ while (segment == null &&
segmentsIterator.hasNext()) {
+ segment = segmentsIterator.next();
+ if (segment.isFreed()) {
+ segment = null;
}
+ }
+ while (segment != null) {
+ segment =
releaseSegmentsForOwnerUntilNextOwner(segment, segmentsIterator,
releasedMemory);
Review comment:
I also feel the logic here is quite complicated to understand. I agree that
it would be better to keep the current approach to avoid possible regression.
For the moment, I suggest we explain the approach and performance concerns in
comments for better maintainability.
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