kezhuw commented on a change in pull request #15273:
URL: https://github.com/apache/flink/pull/15273#discussion_r597375675
##########
File path:
flink-core/src/main/java/org/apache/flink/core/memory/MemorySegment.java
##########
@@ -217,10 +222,14 @@ public int size() {
/**
* Checks whether the memory segment was freed.
*
+ * <p>This method internally involves cross-thread synchronization. Do not
use for performance
+ * sensitive code paths.
+ *
* @return <tt>true</tt>, if the memory segment has been freed,
<tt>false</tt> otherwise.
*/
public boolean isFreed() {
- return address > addressLimit;
+ // in performance sensitive cases, use 'address > addressLimit' instead
+ return isFreedAtomic.get();
Review comment:
I think we could promote this atomic handling to
`MemoryUtils.createMemoryCleaner` or even `MemoryUtils.allocateUnsafe`(with
enriched struct). Then we could remove this caveat. I think we are only
guarding unsafe part ? If yes, I recommend to move this concurrent guarding to
unsafe`cleaner`.
##########
File path:
flink-core/src/test/java/org/apache/flink/core/memory/OffHeapUnsafeMemorySegmentTest.java
##########
@@ -58,4 +61,31 @@ public void testCallCleanerOnFree() {
.free();
assertTrue(cleanerFuture.isDone());
}
+
+ @Test
+ public void testCallCleanerOnceOnConcurrentFree() throws
InterruptedException {
+ final AtomicInteger counter = new AtomicInteger(0);
Review comment:
I think we should also test throwing path, in that path the final
`counter` should also be one.
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